Merge branch kvm-arm64/selftest/s2-faults into kvmarm-master/next

* kvm-arm64/selftest/s2-faults:
  : .
  : New KVM/arm64 selftests exercising various sorts of S2 faults, courtesy
  : of Ricardo Koller. From the cover letter:
  :
  : "This series adds a new aarch64 selftest for testing stage 2 fault handling
  : for various combinations of guest accesses (e.g., write, S1PTW), backing
  : sources (e.g., anon), and types of faults (e.g., read on hugetlbfs with a
  : hole, write on a readonly memslot). Each test tries a different combination
  : and then checks that the access results in the right behavior (e.g., uffd
  : faults with the right address and write/read flag). [...]"
  : .
  KVM: selftests: aarch64: Add mix of tests into page_fault_test
  KVM: selftests: aarch64: Add readonly memslot tests into page_fault_test
  KVM: selftests: aarch64: Add dirty logging tests into page_fault_test
  KVM: selftests: aarch64: Add userfaultfd tests into page_fault_test
  KVM: selftests: aarch64: Add aarch64/page_fault_test
  KVM: selftests: Use the right memslot for code, page-tables, and data allocations
  KVM: selftests: Fix alignment in virt_arch_pgd_alloc() and vm_vaddr_alloc()
  KVM: selftests: Add vm->memslots[] and enum kvm_mem_region_type
  KVM: selftests: Stash backing_src_type in struct userspace_mem_region
  tools: Copy bitfield.h from the kernel sources
  KVM: selftests: aarch64: Construct DEFAULT_MAIR_EL1 using sysreg.h macros
  KVM: selftests: Add missing close and munmap in __vm_mem_region_delete()
  KVM: selftests: aarch64: Add virt_get_pte_hva() library function
  KVM: selftests: Add a userfaultfd library
Signed-off-by: Marc Zyngier <maz@kernel.org>

tools/include/linux/bitfield.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2014 Felix Fietkau <nbd@nbd.name>
+ * Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
+ */
+
+#ifndef _LINUX_BITFIELD_H
+#define _LINUX_BITFIELD_H
+
+#include <linux/build_bug.h>
+#include <asm/byteorder.h>
+
+/*
+ * Bitfield access macros
+ *
+ * FIELD_{GET,PREP} macros take as first parameter shifted mask
+ * from which they extract the base mask and shift amount.
+ * Mask must be a compilation time constant.
+ *
+ * Example:
+ *
+ *  #define REG_FIELD_A  GENMASK(6, 0)
+ *  #define REG_FIELD_B  BIT(7)
+ *  #define REG_FIELD_C  GENMASK(15, 8)
+ *  #define REG_FIELD_D  GENMASK(31, 16)
+ *
+ * Get:
+ *  a = FIELD_GET(REG_FIELD_A, reg);
+ *  b = FIELD_GET(REG_FIELD_B, reg);
+ *
+ * Set:
+ *  reg = FIELD_PREP(REG_FIELD_A, 1) |
+ *	  FIELD_PREP(REG_FIELD_B, 0) |
+ *	  FIELD_PREP(REG_FIELD_C, c) |
+ *	  FIELD_PREP(REG_FIELD_D, 0x40);
+ *
+ * Modify:
+ *  reg &= ~REG_FIELD_C;
+ *  reg |= FIELD_PREP(REG_FIELD_C, c);
+ */
+
+#define __bf_shf(x) (__builtin_ffsll(x) - 1)
+
+#define __scalar_type_to_unsigned_cases(type)				\
+		unsigned type:	(unsigned type)0,			\
+		signed type:	(unsigned type)0
+
+#define __unsigned_scalar_typeof(x) typeof(				\
+		_Generic((x),						\
+			char:	(unsigned char)0,			\
+			__scalar_type_to_unsigned_cases(char),		\
+			__scalar_type_to_unsigned_cases(short),		\
+			__scalar_type_to_unsigned_cases(int),		\
+			__scalar_type_to_unsigned_cases(long),		\
+			__scalar_type_to_unsigned_cases(long long),	\
+			default: (x)))
+
+#define __bf_cast_unsigned(type, x)	((__unsigned_scalar_typeof(type))(x))
+
+#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx)			\
+	({								\
+		BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask),		\
+				 _pfx "mask is not constant");		\
+		BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero");	\
+		BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ?		\
+				 ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
+				 _pfx "value too large for the field"); \
+		BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) >	\
+				 __bf_cast_unsigned(_reg, ~0ull),	\
+				 _pfx "type of reg too small for mask"); \
+		__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) +			\
+					      (1ULL << __bf_shf(_mask))); \
+	})
+
+/**
+ * FIELD_MAX() - produce the maximum value representable by a field
+ * @_mask: shifted mask defining the field's length and position
+ *
+ * FIELD_MAX() returns the maximum value that can be held in the field
+ * specified by @_mask.
+ */
+#define FIELD_MAX(_mask)						\
+	({								\
+		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: ");	\
+		(typeof(_mask))((_mask) >> __bf_shf(_mask));		\
+	})
+
+/**
+ * FIELD_FIT() - check if value fits in the field
+ * @_mask: shifted mask defining the field's length and position
+ * @_val:  value to test against the field
+ *
+ * Return: true if @_val can fit inside @_mask, false if @_val is too big.
+ */
+#define FIELD_FIT(_mask, _val)						\
+	({								\
+		__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: ");	\
+		!((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
+	})
+
+/**
+ * FIELD_PREP() - prepare a bitfield element
+ * @_mask: shifted mask defining the field's length and position
+ * @_val:  value to put in the field
+ *
+ * FIELD_PREP() masks and shifts up the value.  The result should
+ * be combined with other fields of the bitfield using logical OR.
+ */
+#define FIELD_PREP(_mask, _val)						\
+	({								\
+		__BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");	\
+		((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);	\
+	})
+
+/**
+ * FIELD_GET() - extract a bitfield element
+ * @_mask: shifted mask defining the field's length and position
+ * @_reg:  value of entire bitfield
+ *
+ * FIELD_GET() extracts the field specified by @_mask from the
+ * bitfield passed in as @_reg by masking and shifting it down.
+ */
+#define FIELD_GET(_mask, _reg)						\
+	({								\
+		__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: ");	\
+		(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask));	\
+	})
+
+extern void __compiletime_error("value doesn't fit into mask")
+__field_overflow(void);
+extern void __compiletime_error("bad bitfield mask")
+__bad_mask(void);
+static __always_inline u64 field_multiplier(u64 field)
+{
+	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
+		__bad_mask();
+	return field & -field;
+}
+static __always_inline u64 field_mask(u64 field)
+{
+	return field / field_multiplier(field);
+}
+#define field_max(field)	((typeof(field))field_mask(field))
+#define ____MAKE_OP(type,base,to,from)					\
+static __always_inline __##type type##_encode_bits(base v, base field)	\
+{									\
+	if (__builtin_constant_p(v) && (v & ~field_mask(field)))	\
+		__field_overflow();					\
+	return to((v & field_mask(field)) * field_multiplier(field));	\
+}									\
+static __always_inline __##type type##_replace_bits(__##type old,	\
+					base val, base field)		\
+{									\
+	return (old & ~to(field)) | type##_encode_bits(val, field);	\
+}									\
+static __always_inline void type##p_replace_bits(__##type *p,		\
+					base val, base field)		\
+{									\
+	*p = (*p & ~to(field)) | type##_encode_bits(val, field);	\
+}									\
+static __always_inline base type##_get_bits(__##type v, base field)	\
+{									\
+	return (from(v) & field)/field_multiplier(field);		\
+}
+#define __MAKE_OP(size)							\
+	____MAKE_OP(le##size,u##size,cpu_to_le##size,le##size##_to_cpu)	\
+	____MAKE_OP(be##size,u##size,cpu_to_be##size,be##size##_to_cpu)	\
+	____MAKE_OP(u##size,u##size,,)
+____MAKE_OP(u8,u8,,)
+__MAKE_OP(16)
+__MAKE_OP(32)
+__MAKE_OP(64)
+#undef __MAKE_OP
+#undef ____MAKE_OP
+
+#endif

tools/testing/selftests/kvm/.gitignore

@@ -4,6 +4,7 @@
 /aarch64/debug-exceptions
 /aarch64/get-reg-list
 /aarch64/hypercalls
+/aarch64/page_fault_test
 /aarch64/psci_test
 /aarch64/vcpu_width_config
 /aarch64/vgic_init

tools/testing/selftests/kvm/Makefile

@@ -47,6 +47,7 @@ LIBKVM += lib/perf_test_util.c
 LIBKVM += lib/rbtree.c
 LIBKVM += lib/sparsebit.c
 LIBKVM += lib/test_util.c
+LIBKVM += lib/userfaultfd_util.c
 
 LIBKVM_STRING += lib/string_override.c
 
@@ -152,6 +153,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/arch_timer
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/hypercalls
+TEST_GEN_PROGS_aarch64 += aarch64/page_fault_test
 TEST_GEN_PROGS_aarch64 += aarch64/psci_test
 TEST_GEN_PROGS_aarch64 += aarch64/vcpu_width_config
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init

tools/testing/selftests/kvm/aarch64/page_fault_test.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * page_fault_test.c - Test stage 2 faults.
+ *
+ * This test tries different combinations of guest accesses (e.g., write,
+ * S1PTW), backing source type (e.g., anon) and types of faults (e.g., read on
+ * hugetlbfs with a hole). It checks that the expected handling method is
+ * called (e.g., uffd faults with the right address and write/read flag).
+ */
+
+#define _GNU_SOURCE
+#include <linux/bitmap.h>
+#include <fcntl.h>
+#include <test_util.h>
+#include <kvm_util.h>
+#include <processor.h>
+#include <asm/sysreg.h>
+#include <linux/bitfield.h>
+#include "guest_modes.h"
+#include "userfaultfd_util.h"
+
+/* Guest virtual addresses that point to the test page and its PTE. */
+#define TEST_GVA				0xc0000000
+#define TEST_EXEC_GVA				(TEST_GVA + 0x8)
+#define TEST_PTE_GVA				0xb0000000
+#define TEST_DATA				0x0123456789ABCDEF
+
+static uint64_t *guest_test_memory = (uint64_t *)TEST_GVA;
+
+#define CMD_NONE				(0)
+#define CMD_SKIP_TEST				(1ULL << 1)
+#define CMD_HOLE_PT				(1ULL << 2)
+#define CMD_HOLE_DATA				(1ULL << 3)
+#define CMD_CHECK_WRITE_IN_DIRTY_LOG		(1ULL << 4)
+#define CMD_CHECK_S1PTW_WR_IN_DIRTY_LOG		(1ULL << 5)
+#define CMD_CHECK_NO_WRITE_IN_DIRTY_LOG		(1ULL << 6)
+#define CMD_CHECK_NO_S1PTW_WR_IN_DIRTY_LOG	(1ULL << 7)
+#define CMD_SET_PTE_AF				(1ULL << 8)
+
+#define PREPARE_FN_NR				10
+#define CHECK_FN_NR				10
+
+static struct event_cnt {
+	int mmio_exits;
+	int fail_vcpu_runs;
+	int uffd_faults;
+	/* uffd_faults is incremented from multiple threads. */
+	pthread_mutex_t uffd_faults_mutex;
+} events;
+
+struct test_desc {
+	const char *name;
+	uint64_t mem_mark_cmd;
+	/* Skip the test if any prepare function returns false */
+	bool (*guest_prepare[PREPARE_FN_NR])(void);
+	void (*guest_test)(void);
+	void (*guest_test_check[CHECK_FN_NR])(void);
+	uffd_handler_t uffd_pt_handler;
+	uffd_handler_t uffd_data_handler;
+	void (*dabt_handler)(struct ex_regs *regs);
+	void (*iabt_handler)(struct ex_regs *regs);
+	void (*mmio_handler)(struct kvm_vm *vm, struct kvm_run *run);
+	void (*fail_vcpu_run_handler)(int ret);
+	uint32_t pt_memslot_flags;
+	uint32_t data_memslot_flags;
+	bool skip;
+	struct event_cnt expected_events;
+};
+
+struct test_params {
+	enum vm_mem_backing_src_type src_type;
+	struct test_desc *test_desc;
+};
+
+static inline void flush_tlb_page(uint64_t vaddr)
+{
+	uint64_t page = vaddr >> 12;
+
+	dsb(ishst);
+	asm volatile("tlbi vaae1is, %0" :: "r" (page));
+	dsb(ish);
+	isb();
+}
+
+static void guest_write64(void)
+{
+	uint64_t val;
+
+	WRITE_ONCE(*guest_test_memory, TEST_DATA);
+	val = READ_ONCE(*guest_test_memory);
+	GUEST_ASSERT_EQ(val, TEST_DATA);
+}
+
+/* Check the system for atomic instructions. */
+static bool guest_check_lse(void)
+{
+	uint64_t isar0 = read_sysreg(id_aa64isar0_el1);
+	uint64_t atomic;
+
+	atomic = FIELD_GET(ARM64_FEATURE_MASK(ID_AA64ISAR0_ATOMICS), isar0);
+	return atomic >= 2;
+}
+
+static bool guest_check_dc_zva(void)
+{
+	uint64_t dczid = read_sysreg(dczid_el0);
+	uint64_t dzp = FIELD_GET(ARM64_FEATURE_MASK(DCZID_DZP), dczid);
+
+	return dzp == 0;
+}
+
+/* Compare and swap instruction. */
+static void guest_cas(void)
+{
+	uint64_t val;
+
+	GUEST_ASSERT(guest_check_lse());
+	asm volatile(".arch_extension lse\n"
+		     "casal %0, %1, [%2]\n"
+		     :: "r" (0), "r" (TEST_DATA), "r" (guest_test_memory));
+	val = READ_ONCE(*guest_test_memory);
+	GUEST_ASSERT_EQ(val, TEST_DATA);
+}
+
+static void guest_read64(void)
+{
+	uint64_t val;
+
+	val = READ_ONCE(*guest_test_memory);
+	GUEST_ASSERT_EQ(val, 0);
+}
+
+/* Address translation instruction */
+static void guest_at(void)
+{
+	uint64_t par;
+
+	asm volatile("at s1e1r, %0" :: "r" (guest_test_memory));
+	par = read_sysreg(par_el1);
+	isb();
+
+	/* Bit 1 indicates whether the AT was successful */
+	GUEST_ASSERT_EQ(par & 1, 0);
+}
+
+/*
+ * The size of the block written by "dc zva" is guaranteed to be between (2 <<
+ * 0) and (2 << 9), which is safe in our case as we need the write to happen
+ * for at least a word, and not more than a page.
+ */
+static void guest_dc_zva(void)
+{
+	uint16_t val;
+
+	asm volatile("dc zva, %0" :: "r" (guest_test_memory));
+	dsb(ish);
+	val = READ_ONCE(*guest_test_memory);
+	GUEST_ASSERT_EQ(val, 0);
+}
+
+/*
+ * Pre-indexing loads and stores don't have a valid syndrome (ESR_EL2.ISV==0).
+ * And that's special because KVM must take special care with those: they
+ * should still count as accesses for dirty logging or user-faulting, but
+ * should be handled differently on mmio.
+ */
+static void guest_ld_preidx(void)
+{
+	uint64_t val;
+	uint64_t addr = TEST_GVA - 8;
+
+	/*
+	 * This ends up accessing "TEST_GVA + 8 - 8", where "TEST_GVA - 8" is
+	 * in a gap between memslots not backing by anything.
+	 */
+	asm volatile("ldr %0, [%1, #8]!"
+		     : "=r" (val), "+r" (addr));
+	GUEST_ASSERT_EQ(val, 0);
+	GUEST_ASSERT_EQ(addr, TEST_GVA);
+}
+
+static void guest_st_preidx(void)
+{
+	uint64_t val = TEST_DATA;
+	uint64_t addr = TEST_GVA - 8;
+
+	asm volatile("str %0, [%1, #8]!"
+		     : "+r" (val), "+r" (addr));
+
+	GUEST_ASSERT_EQ(addr, TEST_GVA);
+	val = READ_ONCE(*guest_test_memory);
+}
+
+static bool guest_set_ha(void)
+{
+	uint64_t mmfr1 = read_sysreg(id_aa64mmfr1_el1);
+	uint64_t hadbs, tcr;
+
+	/* Skip if HA is not supported. */
+	hadbs = FIELD_GET(ARM64_FEATURE_MASK(ID_AA64MMFR1_HADBS), mmfr1);
+	if (hadbs == 0)
+		return false;
+
+	tcr = read_sysreg(tcr_el1) | TCR_EL1_HA;
+	write_sysreg(tcr, tcr_el1);
+	isb();
+
+	return true;
+}
+
+static bool guest_clear_pte_af(void)
+{
+	*((uint64_t *)TEST_PTE_GVA) &= ~PTE_AF;
+	flush_tlb_page(TEST_GVA);
+
+	return true;
+}
+
+static void guest_check_pte_af(void)
+{
+	dsb(ish);
+	GUEST_ASSERT_EQ(*((uint64_t *)TEST_PTE_GVA) & PTE_AF, PTE_AF);
+}
+
+static void guest_check_write_in_dirty_log(void)
+{
+	GUEST_SYNC(CMD_CHECK_WRITE_IN_DIRTY_LOG);
+}
+
+static void guest_check_no_write_in_dirty_log(void)
+{
+	GUEST_SYNC(CMD_CHECK_NO_WRITE_IN_DIRTY_LOG);
+}
+
+static void guest_check_s1ptw_wr_in_dirty_log(void)
+{
+	GUEST_SYNC(CMD_CHECK_S1PTW_WR_IN_DIRTY_LOG);
+}
+
+static void guest_exec(void)
+{
+	int (*code)(void) = (int (*)(void))TEST_EXEC_GVA;
+	int ret;
+
+	ret = code();
+	GUEST_ASSERT_EQ(ret, 0x77);
+}
+
+static bool guest_prepare(struct test_desc *test)
+{
+	bool (*prepare_fn)(void);
+	int i;
+
+	for (i = 0; i < PREPARE_FN_NR; i++) {
+		prepare_fn = test->guest_prepare[i];
+		if (prepare_fn && !prepare_fn())
+			return false;
+	}
+
+	return true;
+}
+
+static void guest_test_check(struct test_desc *test)
+{
+	void (*check_fn)(void);
+	int i;
+
+	for (i = 0; i < CHECK_FN_NR; i++) {
+		check_fn = test->guest_test_check[i];
+		if (check_fn)
+			check_fn();
+	}
+}
+
+static void guest_code(struct test_desc *test)
+{
+	if (!guest_prepare(test))
+		GUEST_SYNC(CMD_SKIP_TEST);
+
+	GUEST_SYNC(test->mem_mark_cmd);
+
+	if (test->guest_test)
+		test->guest_test();
+
+	guest_test_check(test);
+	GUEST_DONE();
+}
+
+static void no_dabt_handler(struct ex_regs *regs)
+{
+	GUEST_ASSERT_1(false, read_sysreg(far_el1));
+}
+
+static void no_iabt_handler(struct ex_regs *regs)
+{
+	GUEST_ASSERT_1(false, regs->pc);
+}
+
+static struct uffd_args {
+	char *copy;
+	void *hva;
+	uint64_t paging_size;
+} pt_args, data_args;
+
+/* Returns true to continue the test, and false if it should be skipped. */
+static int uffd_generic_handler(int uffd_mode, int uffd, struct uffd_msg *msg,
+				struct uffd_args *args, bool expect_write)
+{
+	uint64_t addr = msg->arg.pagefault.address;
+	uint64_t flags = msg->arg.pagefault.flags;
+	struct uffdio_copy copy;
+	int ret;
+
+	TEST_ASSERT(uffd_mode == UFFDIO_REGISTER_MODE_MISSING,
+		    "The only expected UFFD mode is MISSING");
+	ASSERT_EQ(!!(flags & UFFD_PAGEFAULT_FLAG_WRITE), expect_write);
+	ASSERT_EQ(addr, (uint64_t)args->hva);
+
+	pr_debug("uffd fault: addr=%p write=%d\n",
+		 (void *)addr, !!(flags & UFFD_PAGEFAULT_FLAG_WRITE));
+
+	copy.src = (uint64_t)args->copy;
+	copy.dst = addr;
+	copy.len = args->paging_size;
+	copy.mode = 0;
+
+	ret = ioctl(uffd, UFFDIO_COPY, &copy);
+	if (ret == -1) {
+		pr_info("Failed UFFDIO_COPY in 0x%lx with errno: %d\n",
+			addr, errno);
+		return ret;
+	}
+
+	pthread_mutex_lock(&events.uffd_faults_mutex);
+	events.uffd_faults += 1;
+	pthread_mutex_unlock(&events.uffd_faults_mutex);
+	return 0;
+}
+
+static int uffd_pt_write_handler(int mode, int uffd, struct uffd_msg *msg)
+{
+	return uffd_generic_handler(mode, uffd, msg, &pt_args, true);
+}
+
+static int uffd_data_write_handler(int mode, int uffd, struct uffd_msg *msg)
+{
+	return uffd_generic_handler(mode, uffd, msg, &data_args, true);
+}
+
+static int uffd_data_read_handler(int mode, int uffd, struct uffd_msg *msg)
+{
+	return uffd_generic_handler(mode, uffd, msg, &data_args, false);
+}
+
+static void setup_uffd_args(struct userspace_mem_region *region,
+			    struct uffd_args *args)
+{
+	args->hva = (void *)region->region.userspace_addr;
+	args->paging_size = region->region.memory_size;
+
+	args->copy = malloc(args->paging_size);
+	TEST_ASSERT(args->copy, "Failed to allocate data copy.");
+	memcpy(args->copy, args->hva, args->paging_size);
+}
+
+static void setup_uffd(struct kvm_vm *vm, struct test_params *p,
+		       struct uffd_desc **pt_uffd, struct uffd_desc **data_uffd)
+{
+	struct test_desc *test = p->test_desc;
+	int uffd_mode = UFFDIO_REGISTER_MODE_MISSING;
+
+	setup_uffd_args(vm_get_mem_region(vm, MEM_REGION_PT), &pt_args);
+	setup_uffd_args(vm_get_mem_region(vm, MEM_REGION_TEST_DATA), &data_args);
+
+	*pt_uffd = NULL;
+	if (test->uffd_pt_handler)
+		*pt_uffd = uffd_setup_demand_paging(uffd_mode, 0,
+						    pt_args.hva,
+						    pt_args.paging_size,
+						    test->uffd_pt_handler);
+
+	*data_uffd = NULL;
+	if (test->uffd_data_handler)
+		*data_uffd = uffd_setup_demand_paging(uffd_mode, 0,
+						      data_args.hva,
+						      data_args.paging_size,
+						      test->uffd_data_handler);
+}
+
+static void free_uffd(struct test_desc *test, struct uffd_desc *pt_uffd,
+		      struct uffd_desc *data_uffd)
+{
+	if (test->uffd_pt_handler)
+		uffd_stop_demand_paging(pt_uffd);
+	if (test->uffd_data_handler)
+		uffd_stop_demand_paging(data_uffd);
+
+	free(pt_args.copy);
+	free(data_args.copy);
+}
+
+static int uffd_no_handler(int mode, int uffd, struct uffd_msg *msg)
+{
+	TEST_FAIL("There was no UFFD fault expected.");
+	return -1;
+}
+
+/* Returns false if the test should be skipped. */
+static bool punch_hole_in_backing_store(struct kvm_vm *vm,
+					struct userspace_mem_region *region)
+{
+	void *hva = (void *)region->region.userspace_addr;
+	uint64_t paging_size = region->region.memory_size;
+	int ret, fd = region->fd;
+
+	if (fd != -1) {
+		ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+				0, paging_size);
+		TEST_ASSERT(ret == 0, "fallocate failed\n");
+	} else {
+		ret = madvise(hva, paging_size, MADV_DONTNEED);
+		TEST_ASSERT(ret == 0, "madvise failed\n");
+	}
+
+	return true;
+}
+
+static void mmio_on_test_gpa_handler(struct kvm_vm *vm, struct kvm_run *run)
+{
+	struct userspace_mem_region *region;
+	void *hva;
+
+	region = vm_get_mem_region(vm, MEM_REGION_TEST_DATA);
+	hva = (void *)region->region.userspace_addr;
+
+	ASSERT_EQ(run->mmio.phys_addr, region->region.guest_phys_addr);
+
+	memcpy(hva, run->mmio.data, run->mmio.len);
+	events.mmio_exits += 1;
+}
+
+static void mmio_no_handler(struct kvm_vm *vm, struct kvm_run *run)
+{
+	uint64_t data;
+
+	memcpy(&data, run->mmio.data, sizeof(data));
+	pr_debug("addr=%lld len=%d w=%d data=%lx\n",
+		 run->mmio.phys_addr, run->mmio.len,
+		 run->mmio.is_write, data);
+	TEST_FAIL("There was no MMIO exit expected.");
+}
+
+static bool check_write_in_dirty_log(struct kvm_vm *vm,
+				     struct userspace_mem_region *region,
+				     uint64_t host_pg_nr)
+{
+	unsigned long *bmap;
+	bool first_page_dirty;
+	uint64_t size = region->region.memory_size;
+
+	/* getpage_size() is not always equal to vm->page_size */
+	bmap = bitmap_zalloc(size / getpagesize());
+	kvm_vm_get_dirty_log(vm, region->region.slot, bmap);
+	first_page_dirty = test_bit(host_pg_nr, bmap);
+	free(bmap);
+	return first_page_dirty;
+}
+
+/* Returns true to continue the test, and false if it should be skipped. */
+static bool handle_cmd(struct kvm_vm *vm, int cmd)
+{
+	struct userspace_mem_region *data_region, *pt_region;
+	bool continue_test = true;
+
+	data_region = vm_get_mem_region(vm, MEM_REGION_TEST_DATA);
+	pt_region = vm_get_mem_region(vm, MEM_REGION_PT);
+
+	if (cmd == CMD_SKIP_TEST)
+		continue_test = false;
+
+	if (cmd & CMD_HOLE_PT)
+		continue_test = punch_hole_in_backing_store(vm, pt_region);
+	if (cmd & CMD_HOLE_DATA)
+		continue_test = punch_hole_in_backing_store(vm, data_region);
+	if (cmd & CMD_CHECK_WRITE_IN_DIRTY_LOG)
+		TEST_ASSERT(check_write_in_dirty_log(vm, data_region, 0),
+			    "Missing write in dirty log");
+	if (cmd & CMD_CHECK_S1PTW_WR_IN_DIRTY_LOG)
+		TEST_ASSERT(check_write_in_dirty_log(vm, pt_region, 0),
+			    "Missing s1ptw write in dirty log");
+	if (cmd & CMD_CHECK_NO_WRITE_IN_DIRTY_LOG)
+		TEST_ASSERT(!check_write_in_dirty_log(vm, data_region, 0),
+			    "Unexpected write in dirty log");
+	if (cmd & CMD_CHECK_NO_S1PTW_WR_IN_DIRTY_LOG)
+		TEST_ASSERT(!check_write_in_dirty_log(vm, pt_region, 0),
+			    "Unexpected s1ptw write in dirty log");
+
+	return continue_test;
+}
+
+void fail_vcpu_run_no_handler(int ret)
+{
+	TEST_FAIL("Unexpected vcpu run failure\n");
+}
+
+void fail_vcpu_run_mmio_no_syndrome_handler(int ret)
+{
+	TEST_ASSERT(errno == ENOSYS,
+		    "The mmio handler should have returned not implemented.");
+	events.fail_vcpu_runs += 1;
+}
+
+typedef uint32_t aarch64_insn_t;
+extern aarch64_insn_t __exec_test[2];
+
+noinline void __return_0x77(void)
+{
+	asm volatile("__exec_test: mov x0, #0x77\n"
+		     "ret\n");
+}
+
+/*
+ * Note that this function runs on the host before the test VM starts: there's
+ * no need to sync the D$ and I$ caches.
+ */
+static void load_exec_code_for_test(struct kvm_vm *vm)
+{
+	uint64_t *code;
+	struct userspace_mem_region *region;
+	void *hva;
+
+	region = vm_get_mem_region(vm, MEM_REGION_TEST_DATA);
+	hva = (void *)region->region.userspace_addr;
+
+	assert(TEST_EXEC_GVA > TEST_GVA);
+	code = hva + TEST_EXEC_GVA - TEST_GVA;
+	memcpy(code, __exec_test, sizeof(__exec_test));
+}
+
+static void setup_abort_handlers(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
+				 struct test_desc *test)
+{
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vcpu);
+
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_EC_DABT, no_dabt_handler);
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_EC_IABT, no_iabt_handler);
+}
+
+static void setup_gva_maps(struct kvm_vm *vm)
+{
+	struct userspace_mem_region *region;
+	uint64_t pte_gpa;
+
+	region = vm_get_mem_region(vm, MEM_REGION_TEST_DATA);
+	/* Map TEST_GVA first. This will install a new PTE. */
+	virt_pg_map(vm, TEST_GVA, region->region.guest_phys_addr);
+	/* Then map TEST_PTE_GVA to the above PTE. */
+	pte_gpa = addr_hva2gpa(vm, virt_get_pte_hva(vm, TEST_GVA));
+	virt_pg_map(vm, TEST_PTE_GVA, pte_gpa);
+}
+
+enum pf_test_memslots {
+	CODE_AND_DATA_MEMSLOT,
+	PAGE_TABLE_MEMSLOT,
+	TEST_DATA_MEMSLOT,
+};
+
+/*
+ * Create a memslot for code and data at pfn=0, and test-data and PT ones
+ * at max_gfn.
+ */
+static void setup_memslots(struct kvm_vm *vm, struct test_params *p)
+{
+	uint64_t backing_src_pagesz = get_backing_src_pagesz(p->src_type);
+	uint64_t guest_page_size = vm->page_size;
+	uint64_t max_gfn = vm_compute_max_gfn(vm);
+	/* Enough for 2M of code when using 4K guest pages. */
+	uint64_t code_npages = 512;
+	uint64_t pt_size, data_size, data_gpa;
+
+	/*
+	 * This test requires 1 pgd, 2 pud, 4 pmd, and 6 pte pages when using
+	 * VM_MODE_P48V48_4K. Note that the .text takes ~1.6MBs.  That's 13
+	 * pages. VM_MODE_P48V48_4K is the mode with most PT pages; let's use
+	 * twice that just in case.
+	 */
+	pt_size = 26 * guest_page_size;
+
+	/* memslot sizes and gpa's must be aligned to the backing page size */
+	pt_size = align_up(pt_size, backing_src_pagesz);
+	data_size = align_up(guest_page_size, backing_src_pagesz);
+	data_gpa = (max_gfn * guest_page_size) - data_size;
+	data_gpa = align_down(data_gpa, backing_src_pagesz);
+
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, 0,
+				    CODE_AND_DATA_MEMSLOT, code_npages, 0);
+	vm->memslots[MEM_REGION_CODE] = CODE_AND_DATA_MEMSLOT;
+	vm->memslots[MEM_REGION_DATA] = CODE_AND_DATA_MEMSLOT;
+
+	vm_userspace_mem_region_add(vm, p->src_type, data_gpa - pt_size,
+				    PAGE_TABLE_MEMSLOT, pt_size / guest_page_size,
+				    p->test_desc->pt_memslot_flags);
+	vm->memslots[MEM_REGION_PT] = PAGE_TABLE_MEMSLOT;
+
+	vm_userspace_mem_region_add(vm, p->src_type, data_gpa, TEST_DATA_MEMSLOT,
+				    data_size / guest_page_size,
+				    p->test_desc->data_memslot_flags);
+	vm->memslots[MEM_REGION_TEST_DATA] = TEST_DATA_MEMSLOT;
+}
+
+static void setup_default_handlers(struct test_desc *test)
+{
+	if (!test->mmio_handler)
+		test->mmio_handler = mmio_no_handler;
+
+	if (!test->fail_vcpu_run_handler)
+		test->fail_vcpu_run_handler = fail_vcpu_run_no_handler;
+}
+
+static void check_event_counts(struct test_desc *test)
+{
+	ASSERT_EQ(test->expected_events.uffd_faults, events.uffd_faults);
+	ASSERT_EQ(test->expected_events.mmio_exits, events.mmio_exits);
+	ASSERT_EQ(test->expected_events.fail_vcpu_runs, events.fail_vcpu_runs);
+}
+
+static void print_test_banner(enum vm_guest_mode mode, struct test_params *p)
+{
+	struct test_desc *test = p->test_desc;
+
+	pr_debug("Test: %s\n", test->name);
+	pr_debug("Testing guest mode: %s\n", vm_guest_mode_string(mode));
+	pr_debug("Testing memory backing src type: %s\n",
+		 vm_mem_backing_src_alias(p->src_type)->name);
+}
+
+static void reset_event_counts(void)
+{
+	memset(&events, 0, sizeof(events));
+}
+
+/*
+ * This function either succeeds, skips the test (after setting test->skip), or
+ * fails with a TEST_FAIL that aborts all tests.
+ */
+static void vcpu_run_loop(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
+			  struct test_desc *test)
+{
+	struct kvm_run *run;
+	struct ucall uc;
+	int ret;
+
+	run = vcpu->run;
+
+	for (;;) {
+		ret = _vcpu_run(vcpu);
+		if (ret) {
+			test->fail_vcpu_run_handler(ret);
+			goto done;
+		}
+
+		switch (get_ucall(vcpu, &uc)) {
+		case UCALL_SYNC:
+			if (!handle_cmd(vm, uc.args[1])) {
+				test->skip = true;
+				goto done;
+			}
+			break;
+		case UCALL_ABORT:
+			REPORT_GUEST_ASSERT_2(uc, "values: %#lx, %#lx");
+			break;
+		case UCALL_DONE:
+			goto done;
+		case UCALL_NONE:
+			if (run->exit_reason == KVM_EXIT_MMIO)
+				test->mmio_handler(vm, run);
+			break;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		}
+	}
+
+done:
+	pr_debug(test->skip ? "Skipped.\n" : "Done.\n");
+}
+
+static void run_test(enum vm_guest_mode mode, void *arg)
+{
+	struct test_params *p = (struct test_params *)arg;
+	struct test_desc *test = p->test_desc;
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	struct uffd_desc *pt_uffd, *data_uffd;
+
+	print_test_banner(mode, p);
+
+	vm = ____vm_create(mode);
+	setup_memslots(vm, p);
+	kvm_vm_elf_load(vm, program_invocation_name);
+	vcpu = vm_vcpu_add(vm, 0, guest_code);
+
+	setup_gva_maps(vm);
+
+	ucall_init(vm, NULL);
+
+	reset_event_counts();
+
+	/*
+	 * Set some code in the data memslot for the guest to execute (only
+	 * applicable to the EXEC tests). This has to be done before
+	 * setup_uffd() as that function copies the memslot data for the uffd
+	 * handler.
+	 */
+	load_exec_code_for_test(vm);
+	setup_uffd(vm, p, &pt_uffd, &data_uffd);
+	setup_abort_handlers(vm, vcpu, test);
+	setup_default_handlers(test);
+	vcpu_args_set(vcpu, 1, test);
+
+	vcpu_run_loop(vm, vcpu, test);
+
+	ucall_uninit(vm);
+	kvm_vm_free(vm);
+	free_uffd(test, pt_uffd, data_uffd);
+
+	/*
+	 * Make sure we check the events after the uffd threads have exited,
+	 * which means they updated their respective event counters.
+	 */
+	if (!test->skip)
+		check_event_counts(test);
+}
+
+static void help(char *name)
+{
+	puts("");
+	printf("usage: %s [-h] [-s mem-type]\n", name);
+	puts("");
+	guest_modes_help();
+	backing_src_help("-s");
+	puts("");
+}
+
+#define SNAME(s)			#s
+#define SCAT2(a, b)			SNAME(a ## _ ## b)
+#define SCAT3(a, b, c)			SCAT2(a, SCAT2(b, c))
+#define SCAT4(a, b, c, d)		SCAT2(a, SCAT3(b, c, d))
+
+#define _CHECK(_test)			_CHECK_##_test
+#define _PREPARE(_test)			_PREPARE_##_test
+#define _PREPARE_guest_read64		NULL
+#define _PREPARE_guest_ld_preidx	NULL
+#define _PREPARE_guest_write64		NULL
+#define _PREPARE_guest_st_preidx	NULL
+#define _PREPARE_guest_exec		NULL
+#define _PREPARE_guest_at		NULL
+#define _PREPARE_guest_dc_zva		guest_check_dc_zva
+#define _PREPARE_guest_cas		guest_check_lse
+
+/* With or without access flag checks */
+#define _PREPARE_with_af		guest_set_ha, guest_clear_pte_af
+#define _PREPARE_no_af			NULL
+#define _CHECK_with_af			guest_check_pte_af
+#define _CHECK_no_af			NULL
+
+/* Performs an access and checks that no faults were triggered. */
+#define TEST_ACCESS(_access, _with_af, _mark_cmd)				\
+{										\
+	.name			= SCAT3(_access, _with_af, #_mark_cmd),		\
+	.guest_prepare		= { _PREPARE(_with_af),				\
+				    _PREPARE(_access) },			\
+	.mem_mark_cmd		= _mark_cmd,					\
+	.guest_test		= _access,					\
+	.guest_test_check	= { _CHECK(_with_af) },				\
+	.expected_events	= { 0 },					\
+}
+
+#define TEST_UFFD(_access, _with_af, _mark_cmd,					\
+		  _uffd_data_handler, _uffd_pt_handler, _uffd_faults)		\
+{										\
+	.name			= SCAT4(uffd, _access, _with_af, #_mark_cmd),	\
+	.guest_prepare		= { _PREPARE(_with_af),				\
+				    _PREPARE(_access) },			\
+	.guest_test		= _access,					\
+	.mem_mark_cmd		= _mark_cmd,					\
+	.guest_test_check	= { _CHECK(_with_af) },				\
+	.uffd_data_handler	= _uffd_data_handler,				\
+	.uffd_pt_handler	= _uffd_pt_handler,				\
+	.expected_events	= { .uffd_faults = _uffd_faults, },		\
+}
+
+#define TEST_DIRTY_LOG(_access, _with_af, _test_check)				\
+{										\
+	.name			= SCAT3(dirty_log, _access, _with_af),		\
+	.data_memslot_flags	= KVM_MEM_LOG_DIRTY_PAGES,			\
+	.pt_memslot_flags	= KVM_MEM_LOG_DIRTY_PAGES,			\
+	.guest_prepare		= { _PREPARE(_with_af),				\
+				    _PREPARE(_access) },			\
+	.guest_test		= _access,					\
+	.guest_test_check	= { _CHECK(_with_af), _test_check,		\
+				    guest_check_s1ptw_wr_in_dirty_log},		\
+	.expected_events	= { 0 },					\
+}
+
+#define TEST_UFFD_AND_DIRTY_LOG(_access, _with_af, _uffd_data_handler,		\
+				_uffd_faults, _test_check)			\
+{										\
+	.name			= SCAT3(uffd_and_dirty_log, _access, _with_af),	\
+	.data_memslot_flags	= KVM_MEM_LOG_DIRTY_PAGES,			\
+	.pt_memslot_flags	= KVM_MEM_LOG_DIRTY_PAGES,			\
+	.guest_prepare		= { _PREPARE(_with_af),				\
+				    _PREPARE(_access) },			\
+	.guest_test		= _access,					\
+	.mem_mark_cmd		= CMD_HOLE_DATA | CMD_HOLE_PT,			\
+	.guest_test_check	= { _CHECK(_with_af), _test_check },		\
+	.uffd_data_handler	= _uffd_data_handler,				\
+	.uffd_pt_handler	= uffd_pt_write_handler,			\
+	.expected_events	= { .uffd_faults = _uffd_faults, },		\
+}
+
+#define TEST_RO_MEMSLOT(_access, _mmio_handler, _mmio_exits)			\
+{										\
+	.name			= SCAT3(ro_memslot, _access, _with_af),		\
+	.data_memslot_flags	= KVM_MEM_READONLY,				\
+	.guest_prepare		= { _PREPARE(_access) },			\
+	.guest_test		= _access,					\
+	.mmio_handler		= _mmio_handler,				\
+	.expected_events	= { .mmio_exits = _mmio_exits },		\
+}
+
+#define TEST_RO_MEMSLOT_NO_SYNDROME(_access)					\
+{										\
+	.name			= SCAT2(ro_memslot_no_syndrome, _access),	\
+	.data_memslot_flags	= KVM_MEM_READONLY,				\
+	.guest_test		= _access,					\
+	.fail_vcpu_run_handler	= fail_vcpu_run_mmio_no_syndrome_handler,	\
+	.expected_events	= { .fail_vcpu_runs = 1 },			\
+}
+
+#define TEST_RO_MEMSLOT_AND_DIRTY_LOG(_access, _mmio_handler, _mmio_exits,	\
+				      _test_check)				\
+{										\
+	.name			= SCAT3(ro_memslot, _access, _with_af),		\
+	.data_memslot_flags	= KVM_MEM_READONLY | KVM_MEM_LOG_DIRTY_PAGES,	\
+	.pt_memslot_flags	= KVM_MEM_LOG_DIRTY_PAGES,			\
+	.guest_prepare		= { _PREPARE(_access) },			\
+	.guest_test		= _access,					\
+	.guest_test_check	= { _test_check },				\
+	.mmio_handler		= _mmio_handler,				\
+	.expected_events	= { .mmio_exits = _mmio_exits},			\
+}
+
+#define TEST_RO_MEMSLOT_NO_SYNDROME_AND_DIRTY_LOG(_access, _test_check)		\
+{										\
+	.name			= SCAT2(ro_memslot_no_syn_and_dlog, _access),	\
+	.data_memslot_flags	= KVM_MEM_READONLY | KVM_MEM_LOG_DIRTY_PAGES,	\
+	.pt_memslot_flags	= KVM_MEM_LOG_DIRTY_PAGES,			\
+	.guest_test		= _access,					\
+	.guest_test_check	= { _test_check },				\
+	.fail_vcpu_run_handler	= fail_vcpu_run_mmio_no_syndrome_handler,	\
+	.expected_events	= { .fail_vcpu_runs = 1 },			\
+}
+
+#define TEST_RO_MEMSLOT_AND_UFFD(_access, _mmio_handler, _mmio_exits,		\
+				 _uffd_data_handler, _uffd_faults)		\
+{										\
+	.name			= SCAT2(ro_memslot_uffd, _access),		\
+	.data_memslot_flags	= KVM_MEM_READONLY,				\
+	.mem_mark_cmd		= CMD_HOLE_DATA | CMD_HOLE_PT,			\
+	.guest_prepare		= { _PREPARE(_access) },			\
+	.guest_test		= _access,					\
+	.uffd_data_handler	= _uffd_data_handler,				\
+	.uffd_pt_handler	= uffd_pt_write_handler,			\
+	.mmio_handler		= _mmio_handler,				\
+	.expected_events	= { .mmio_exits = _mmio_exits,			\
+				    .uffd_faults = _uffd_faults },		\
+}
+
+#define TEST_RO_MEMSLOT_NO_SYNDROME_AND_UFFD(_access, _uffd_data_handler,	\
+					     _uffd_faults)			\
+{										\
+	.name			= SCAT2(ro_memslot_no_syndrome, _access),	\
+	.data_memslot_flags	= KVM_MEM_READONLY,				\
+	.mem_mark_cmd		= CMD_HOLE_DATA | CMD_HOLE_PT,			\
+	.guest_test		= _access,					\
+	.uffd_data_handler	= _uffd_data_handler,				\
+	.uffd_pt_handler	= uffd_pt_write_handler,			\
+	.fail_vcpu_run_handler	= fail_vcpu_run_mmio_no_syndrome_handler,	\
+	.expected_events	= { .fail_vcpu_runs = 1,			\
+				    .uffd_faults = _uffd_faults },		\
+}
+
+static struct test_desc tests[] = {
+
+	/* Check that HW is setting the Access Flag (AF) (sanity checks). */
+	TEST_ACCESS(guest_read64, with_af, CMD_NONE),
+	TEST_ACCESS(guest_ld_preidx, with_af, CMD_NONE),
+	TEST_ACCESS(guest_cas, with_af, CMD_NONE),
+	TEST_ACCESS(guest_write64, with_af, CMD_NONE),
+	TEST_ACCESS(guest_st_preidx, with_af, CMD_NONE),
+	TEST_ACCESS(guest_dc_zva, with_af, CMD_NONE),
+	TEST_ACCESS(guest_exec, with_af, CMD_NONE),
+
+	/*
+	 * Punch a hole in the data backing store, and then try multiple
+	 * accesses: reads should rturn zeroes, and writes should
+	 * re-populate the page. Moreover, the test also check that no
+	 * exception was generated in the guest.  Note that this
+	 * reading/writing behavior is the same as reading/writing a
+	 * punched page (with fallocate(FALLOC_FL_PUNCH_HOLE)) from
+	 * userspace.
+	 */
+	TEST_ACCESS(guest_read64, no_af, CMD_HOLE_DATA),
+	TEST_ACCESS(guest_cas, no_af, CMD_HOLE_DATA),
+	TEST_ACCESS(guest_ld_preidx, no_af, CMD_HOLE_DATA),
+	TEST_ACCESS(guest_write64, no_af, CMD_HOLE_DATA),
+	TEST_ACCESS(guest_st_preidx, no_af, CMD_HOLE_DATA),
+	TEST_ACCESS(guest_at, no_af, CMD_HOLE_DATA),
+	TEST_ACCESS(guest_dc_zva, no_af, CMD_HOLE_DATA),
+
+	/*
+	 * Punch holes in the data and PT backing stores and mark them for
+	 * userfaultfd handling. This should result in 2 faults: the access
+	 * on the data backing store, and its respective S1 page table walk
+	 * (S1PTW).
+	 */
+	TEST_UFFD(guest_read64, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_read_handler, uffd_pt_write_handler, 2),
+	/* no_af should also lead to a PT write. */
+	TEST_UFFD(guest_read64, no_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_read_handler, uffd_pt_write_handler, 2),
+	/* Note how that cas invokes the read handler. */
+	TEST_UFFD(guest_cas, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_read_handler, uffd_pt_write_handler, 2),
+	/*
+	 * Can't test guest_at with_af as it's IMPDEF whether the AF is set.
+	 * The S1PTW fault should still be marked as a write.
+	 */
+	TEST_UFFD(guest_at, no_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_read_handler, uffd_pt_write_handler, 1),
+	TEST_UFFD(guest_ld_preidx, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_read_handler, uffd_pt_write_handler, 2),
+	TEST_UFFD(guest_write64, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_write_handler, uffd_pt_write_handler, 2),
+	TEST_UFFD(guest_dc_zva, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_write_handler, uffd_pt_write_handler, 2),
+	TEST_UFFD(guest_st_preidx, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_write_handler, uffd_pt_write_handler, 2),
+	TEST_UFFD(guest_exec, with_af, CMD_HOLE_DATA | CMD_HOLE_PT,
+		  uffd_data_read_handler, uffd_pt_write_handler, 2),
+
+	/*
+	 * Try accesses when the data and PT memory regions are both
+	 * tracked for dirty logging.
+	 */
+	TEST_DIRTY_LOG(guest_read64, with_af, guest_check_no_write_in_dirty_log),
+	/* no_af should also lead to a PT write. */
+	TEST_DIRTY_LOG(guest_read64, no_af, guest_check_no_write_in_dirty_log),
+	TEST_DIRTY_LOG(guest_ld_preidx, with_af, guest_check_no_write_in_dirty_log),
+	TEST_DIRTY_LOG(guest_at, no_af, guest_check_no_write_in_dirty_log),
+	TEST_DIRTY_LOG(guest_exec, with_af, guest_check_no_write_in_dirty_log),
+	TEST_DIRTY_LOG(guest_write64, with_af, guest_check_write_in_dirty_log),
+	TEST_DIRTY_LOG(guest_cas, with_af, guest_check_write_in_dirty_log),
+	TEST_DIRTY_LOG(guest_dc_zva, with_af, guest_check_write_in_dirty_log),
+	TEST_DIRTY_LOG(guest_st_preidx, with_af, guest_check_write_in_dirty_log),
+
+	/*
+	 * Access when the data and PT memory regions are both marked for
+	 * dirty logging and UFFD at the same time. The expected result is
+	 * that writes should mark the dirty log and trigger a userfaultfd
+	 * write fault.  Reads/execs should result in a read userfaultfd
+	 * fault, and nothing in the dirty log.  Any S1PTW should result in
+	 * a write in the dirty log and a userfaultfd write.
+	 */
+	TEST_UFFD_AND_DIRTY_LOG(guest_read64, with_af, uffd_data_read_handler, 2,
+				guest_check_no_write_in_dirty_log),
+	/* no_af should also lead to a PT write. */
+	TEST_UFFD_AND_DIRTY_LOG(guest_read64, no_af, uffd_data_read_handler, 2,
+				guest_check_no_write_in_dirty_log),
+	TEST_UFFD_AND_DIRTY_LOG(guest_ld_preidx, with_af, uffd_data_read_handler,
+				2, guest_check_no_write_in_dirty_log),
+	TEST_UFFD_AND_DIRTY_LOG(guest_at, with_af, 0, 1,
+				guest_check_no_write_in_dirty_log),
+	TEST_UFFD_AND_DIRTY_LOG(guest_exec, with_af, uffd_data_read_handler, 2,
+				guest_check_no_write_in_dirty_log),
+	TEST_UFFD_AND_DIRTY_LOG(guest_write64, with_af, uffd_data_write_handler,
+				2, guest_check_write_in_dirty_log),
+	TEST_UFFD_AND_DIRTY_LOG(guest_cas, with_af, uffd_data_read_handler, 2,
+				guest_check_write_in_dirty_log),
+	TEST_UFFD_AND_DIRTY_LOG(guest_dc_zva, with_af, uffd_data_write_handler,
+				2, guest_check_write_in_dirty_log),
+	TEST_UFFD_AND_DIRTY_LOG(guest_st_preidx, with_af,
+				uffd_data_write_handler, 2,
+				guest_check_write_in_dirty_log),
+
+	/*
+	 * Try accesses when the data memory region is marked read-only
+	 * (with KVM_MEM_READONLY). Writes with a syndrome result in an
+	 * MMIO exit, writes with no syndrome (e.g., CAS) result in a
+	 * failed vcpu run, and reads/execs with and without syndroms do
+	 * not fault.
+	 */
+	TEST_RO_MEMSLOT(guest_read64, 0, 0),
+	TEST_RO_MEMSLOT(guest_ld_preidx, 0, 0),
+	TEST_RO_MEMSLOT(guest_at, 0, 0),
+	TEST_RO_MEMSLOT(guest_exec, 0, 0),
+	TEST_RO_MEMSLOT(guest_write64, mmio_on_test_gpa_handler, 1),
+	TEST_RO_MEMSLOT_NO_SYNDROME(guest_dc_zva),
+	TEST_RO_MEMSLOT_NO_SYNDROME(guest_cas),
+	TEST_RO_MEMSLOT_NO_SYNDROME(guest_st_preidx),
+
+	/*
+	 * Access when both the data region is both read-only and marked
+	 * for dirty logging at the same time. The expected result is that
+	 * for writes there should be no write in the dirty log. The
+	 * readonly handling is the same as if the memslot was not marked
+	 * for dirty logging: writes with a syndrome result in an MMIO
+	 * exit, and writes with no syndrome result in a failed vcpu run.
+	 */
+	TEST_RO_MEMSLOT_AND_DIRTY_LOG(guest_read64, 0, 0,
+				      guest_check_no_write_in_dirty_log),
+	TEST_RO_MEMSLOT_AND_DIRTY_LOG(guest_ld_preidx, 0, 0,
+				      guest_check_no_write_in_dirty_log),
+	TEST_RO_MEMSLOT_AND_DIRTY_LOG(guest_at, 0, 0,
+				      guest_check_no_write_in_dirty_log),
+	TEST_RO_MEMSLOT_AND_DIRTY_LOG(guest_exec, 0, 0,
+				      guest_check_no_write_in_dirty_log),
+	TEST_RO_MEMSLOT_AND_DIRTY_LOG(guest_write64, mmio_on_test_gpa_handler,
+				      1, guest_check_no_write_in_dirty_log),
+	TEST_RO_MEMSLOT_NO_SYNDROME_AND_DIRTY_LOG(guest_dc_zva,
+						  guest_check_no_write_in_dirty_log),
+	TEST_RO_MEMSLOT_NO_SYNDROME_AND_DIRTY_LOG(guest_cas,
+						  guest_check_no_write_in_dirty_log),
+	TEST_RO_MEMSLOT_NO_SYNDROME_AND_DIRTY_LOG(guest_st_preidx,
+						  guest_check_no_write_in_dirty_log),
+
+	/*
+	 * Access when the data region is both read-only and punched with
+	 * holes tracked with userfaultfd.  The expected result is the
+	 * union of both userfaultfd and read-only behaviors. For example,
+	 * write accesses result in a userfaultfd write fault and an MMIO
+	 * exit.  Writes with no syndrome result in a failed vcpu run and
+	 * no userfaultfd write fault. Reads result in userfaultfd getting
+	 * triggered.
+	 */
+	TEST_RO_MEMSLOT_AND_UFFD(guest_read64, 0, 0,
+				 uffd_data_read_handler, 2),
+	TEST_RO_MEMSLOT_AND_UFFD(guest_ld_preidx, 0, 0,
+				 uffd_data_read_handler, 2),
+	TEST_RO_MEMSLOT_AND_UFFD(guest_at, 0, 0,
+				 uffd_no_handler, 1),
+	TEST_RO_MEMSLOT_AND_UFFD(guest_exec, 0, 0,
+				 uffd_data_read_handler, 2),
+	TEST_RO_MEMSLOT_AND_UFFD(guest_write64, mmio_on_test_gpa_handler, 1,
+				 uffd_data_write_handler, 2),
+	TEST_RO_MEMSLOT_NO_SYNDROME_AND_UFFD(guest_cas,
+					     uffd_data_read_handler, 2),
+	TEST_RO_MEMSLOT_NO_SYNDROME_AND_UFFD(guest_dc_zva,
+					     uffd_no_handler, 1),
+	TEST_RO_MEMSLOT_NO_SYNDROME_AND_UFFD(guest_st_preidx,
+					     uffd_no_handler, 1),
+
+	{ 0 }
+};
+
+static void for_each_test_and_guest_mode(enum vm_mem_backing_src_type src_type)
+{
+	struct test_desc *t;
+
+	for (t = &tests[0]; t->name; t++) {
+		if (t->skip)
+			continue;
+
+		struct test_params p = {
+			.src_type = src_type,
+			.test_desc = t,
+		};
+
+		for_each_guest_mode(run_test, &p);
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	enum vm_mem_backing_src_type src_type;
+	int opt;
+
+	setbuf(stdout, NULL);
+
+	src_type = DEFAULT_VM_MEM_SRC;
+
+	while ((opt = getopt(argc, argv, "hm:s:")) != -1) {
+		switch (opt) {
+		case 'm':
+			guest_modes_cmdline(optarg);
+			break;
+		case 's':
+			src_type = parse_backing_src_type(optarg);
+			break;
+		case 'h':
+		default:
+			help(argv[0]);
+			exit(0);
+		}
+	}
+
+	for_each_test_and_guest_mode(src_type);
+	return 0;
+}

tools/testing/selftests/kvm/demand_paging_test.c

@@ -22,23 +22,13 @@
 #include "test_util.h"
 #include "perf_test_util.h"
 #include "guest_modes.h"
+#include "userfaultfd_util.h"
 
 #ifdef __NR_userfaultfd
 
-#ifdef PRINT_PER_PAGE_UPDATES
-#define PER_PAGE_DEBUG(...) printf(__VA_ARGS__)
-#else
-#define PER_PAGE_DEBUG(...) _no_printf(__VA_ARGS__)
-#endif
-
-#ifdef PRINT_PER_VCPU_UPDATES
-#define PER_VCPU_DEBUG(...) printf(__VA_ARGS__)
-#else
-#define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__)
-#endif
-
 static int nr_vcpus = 1;
 static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
+
 static size_t demand_paging_size;
 static char *guest_data_prototype;
 
@@ -67,9 +57,11 @@ static void vcpu_worker(struct perf_test_vcpu_args *vcpu_args)
 		       ts_diff.tv_sec, ts_diff.tv_nsec);
 }
 
-static int handle_uffd_page_request(int uffd_mode, int uffd, uint64_t addr)
+static int handle_uffd_page_request(int uffd_mode, int uffd,
+		struct uffd_msg *msg)
 {
 	pid_t tid = syscall(__NR_gettid);
+	uint64_t addr = msg->arg.pagefault.address;
 	struct timespec start;
 	struct timespec ts_diff;
 	int r;
@@ -116,174 +108,32 @@ static int handle_uffd_page_request(int uffd_mode, int uffd, uint64_t addr)
 	return 0;
 }
 
-bool quit_uffd_thread;
-
-struct uffd_handler_args {
+struct test_params {
 	int uffd_mode;
-	int uffd;
-	int pipefd;
-	useconds_t delay;
+	useconds_t uffd_delay;
+	enum vm_mem_backing_src_type src_type;
+	bool partition_vcpu_memory_access;
 };
 
-static void *uffd_handler_thread_fn(void *arg)
-{
-	struct uffd_handler_args *uffd_args = (struct uffd_handler_args *)arg;
-	int uffd = uffd_args->uffd;
-	int pipefd = uffd_args->pipefd;
-	useconds_t delay = uffd_args->delay;
-	int64_t pages = 0;
-	struct timespec start;
-	struct timespec ts_diff;
-
-	clock_gettime(CLOCK_MONOTONIC, &start);
-	while (!quit_uffd_thread) {
-		struct uffd_msg msg;
-		struct pollfd pollfd[2];
-		char tmp_chr;
-		int r;
-		uint64_t addr;
-
-		pollfd[0].fd = uffd;
-		pollfd[0].events = POLLIN;
-		pollfd[1].fd = pipefd;
-		pollfd[1].events = POLLIN;
-
-		r = poll(pollfd, 2, -1);
-		switch (r) {
-		case -1:
-			pr_info("poll err");
-			continue;
-		case 0:
-			continue;
-		case 1:
-			break;
-		default:
-			pr_info("Polling uffd returned %d", r);
-			return NULL;
-		}
-
-		if (pollfd[0].revents & POLLERR) {
-			pr_info("uffd revents has POLLERR");
-			return NULL;
-		}
-
-		if (pollfd[1].revents & POLLIN) {
-			r = read(pollfd[1].fd, &tmp_chr, 1);
-			TEST_ASSERT(r == 1,
-				    "Error reading pipefd in UFFD thread\n");
-			return NULL;
-		}
-
-		if (!(pollfd[0].revents & POLLIN))
-			continue;
-
-		r = read(uffd, &msg, sizeof(msg));
-		if (r == -1) {
-			if (errno == EAGAIN)
-				continue;
-			pr_info("Read of uffd got errno %d\n", errno);
-			return NULL;
-		}
-
-		if (r != sizeof(msg)) {
-			pr_info("Read on uffd returned unexpected size: %d bytes", r);
-			return NULL;
-		}
-
-		if (!(msg.event & UFFD_EVENT_PAGEFAULT))
-			continue;
-
-		if (delay)
-			usleep(delay);
-		addr =  msg.arg.pagefault.address;
-		r = handle_uffd_page_request(uffd_args->uffd_mode, uffd, addr);
-		if (r < 0)
-			return NULL;
-		pages++;
-	}
-
-	ts_diff = timespec_elapsed(start);
-	PER_VCPU_DEBUG("userfaulted %ld pages over %ld.%.9lds. (%f/sec)\n",
-		       pages, ts_diff.tv_sec, ts_diff.tv_nsec,
-		       pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
-
-	return NULL;
-}
-
-static void setup_demand_paging(struct kvm_vm *vm,
-				pthread_t *uffd_handler_thread, int pipefd,
-				int uffd_mode, useconds_t uffd_delay,
-				struct uffd_handler_args *uffd_args,
-				void *hva, void *alias, uint64_t len)
+static void prefault_mem(void *alias, uint64_t len)
 {
-	bool is_minor = (uffd_mode == UFFDIO_REGISTER_MODE_MINOR);
-	int uffd;
-	struct uffdio_api uffdio_api;
-	struct uffdio_register uffdio_register;
-	uint64_t expected_ioctls = ((uint64_t) 1) << _UFFDIO_COPY;
-	int ret;
+	size_t p;
 
-	PER_PAGE_DEBUG("Userfaultfd %s mode, faults resolved with %s\n",
-		       is_minor ? "MINOR" : "MISSING",
-		       is_minor ? "UFFDIO_CONINUE" : "UFFDIO_COPY");
-
-	/* In order to get minor faults, prefault via the alias. */
-	if (is_minor) {
-		size_t p;
-
-		expected_ioctls = ((uint64_t) 1) << _UFFDIO_CONTINUE;
-
-		TEST_ASSERT(alias != NULL, "Alias required for minor faults");
-		for (p = 0; p < (len / demand_paging_size); ++p) {
-			memcpy(alias + (p * demand_paging_size),
-			       guest_data_prototype, demand_paging_size);
-		}
+	TEST_ASSERT(alias != NULL, "Alias required for minor faults");
+	for (p = 0; p < (len / demand_paging_size); ++p) {
+		memcpy(alias + (p * demand_paging_size),
+		       guest_data_prototype, demand_paging_size);
 	}
-
-	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
-	TEST_ASSERT(uffd >= 0, __KVM_SYSCALL_ERROR("userfaultfd()", uffd));
-
-	uffdio_api.api = UFFD_API;
-	uffdio_api.features = 0;
-	ret = ioctl(uffd, UFFDIO_API, &uffdio_api);
-	TEST_ASSERT(ret != -1, __KVM_SYSCALL_ERROR("UFFDIO_API", ret));
-
-	uffdio_register.range.start = (uint64_t)hva;
-	uffdio_register.range.len = len;
-	uffdio_register.mode = uffd_mode;
-	ret = ioctl(uffd, UFFDIO_REGISTER, &uffdio_register);
-	TEST_ASSERT(ret != -1, __KVM_SYSCALL_ERROR("UFFDIO_REGISTER", ret));
-	TEST_ASSERT((uffdio_register.ioctls & expected_ioctls) ==
-		    expected_ioctls, "missing userfaultfd ioctls");
-
-	uffd_args->uffd_mode = uffd_mode;
-	uffd_args->uffd = uffd;
-	uffd_args->pipefd = pipefd;
-	uffd_args->delay = uffd_delay;
-	pthread_create(uffd_handler_thread, NULL, uffd_handler_thread_fn,
-		       uffd_args);
-
-	PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n",
-		       hva, hva + len);
 }
 
-struct test_params {
-	int uffd_mode;
-	useconds_t uffd_delay;
-	enum vm_mem_backing_src_type src_type;
-	bool partition_vcpu_memory_access;
-};
-
 static void run_test(enum vm_guest_mode mode, void *arg)
 {
 	struct test_params *p = arg;
-	pthread_t *uffd_handler_threads = NULL;
-	struct uffd_handler_args *uffd_args = NULL;
+	struct uffd_desc **uffd_descs = NULL;
 	struct timespec start;
 	struct timespec ts_diff;
-	int *pipefds = NULL;
 	struct kvm_vm *vm;
-	int r, i;
+	int i;
 
 	vm = perf_test_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
 				 p->src_type, p->partition_vcpu_memory_access);
@@ -296,15 +146,8 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	memset(guest_data_prototype, 0xAB, demand_paging_size);
 
 	if (p->uffd_mode) {
-		uffd_handler_threads =
-			malloc(nr_vcpus * sizeof(*uffd_handler_threads));
-		TEST_ASSERT(uffd_handler_threads, "Memory allocation failed");
-
-		uffd_args = malloc(nr_vcpus * sizeof(*uffd_args));
-		TEST_ASSERT(uffd_args, "Memory allocation failed");
-
-		pipefds = malloc(sizeof(int) * nr_vcpus * 2);
-		TEST_ASSERT(pipefds, "Unable to allocate memory for pipefd");
+		uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
+		TEST_ASSERT(uffd_descs, "Memory allocation failed");
 
 		for (i = 0; i < nr_vcpus; i++) {
 			struct perf_test_vcpu_args *vcpu_args;
@@ -317,19 +160,17 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 			vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);
 			vcpu_alias = addr_gpa2alias(vm, vcpu_args->gpa);
 
+			prefault_mem(vcpu_alias,
+				vcpu_args->pages * perf_test_args.guest_page_size);
+
 			/*
 			 * Set up user fault fd to handle demand paging
 			 * requests.
 			 */
-			r = pipe2(&pipefds[i * 2],
-				  O_CLOEXEC | O_NONBLOCK);
-			TEST_ASSERT(!r, "Failed to set up pipefd");
-
-			setup_demand_paging(vm, &uffd_handler_threads[i],
-					    pipefds[i * 2], p->uffd_mode,
-					    p->uffd_delay, &uffd_args[i],
-					    vcpu_hva, vcpu_alias,
-					    vcpu_args->pages * perf_test_args.guest_page_size);
+			uffd_descs[i] = uffd_setup_demand_paging(
+				p->uffd_mode, p->uffd_delay, vcpu_hva,
+				vcpu_args->pages * perf_test_args.guest_page_size,
+				&handle_uffd_page_request);
 		}
 	}
 
@@ -344,15 +185,9 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	pr_info("All vCPU threads joined\n");
 
 	if (p->uffd_mode) {
-		char c;
-
 		/* Tell the user fault fd handler threads to quit */
-		for (i = 0; i < nr_vcpus; i++) {
-			r = write(pipefds[i * 2 + 1], &c, 1);
-			TEST_ASSERT(r == 1, "Unable to write to pipefd");
-
-			pthread_join(uffd_handler_threads[i], NULL);
-		}
+		for (i = 0; i < nr_vcpus; i++)
+			uffd_stop_demand_paging(uffd_descs[i]);
 	}
 
 	pr_info("Total guest execution time: %ld.%.9lds\n",
@@ -364,11 +199,8 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	perf_test_destroy_vm(vm);
 
 	free(guest_data_prototype);
-	if (p->uffd_mode) {
-		free(uffd_handler_threads);
-		free(uffd_args);
-		free(pipefds);
-	}
+	if (p->uffd_mode)
+		free(uffd_descs);
 }
 
 static void help(char *name)

tools/testing/selftests/kvm/include/aarch64/processor.h

@@ -38,12 +38,25 @@
  * NORMAL             4     1111:1111
  * NORMAL_WT          5     1011:1011
  */
-#define DEFAULT_MAIR_EL1 ((0x00ul << (0 * 8)) | \
-			  (0x04ul << (1 * 8)) | \
-			  (0x0cul << (2 * 8)) | \
-			  (0x44ul << (3 * 8)) | \
-			  (0xfful << (4 * 8)) | \
-			  (0xbbul << (5 * 8)))
+
+/* Linux doesn't use these memory types, so let's define them. */
+#define MAIR_ATTR_DEVICE_GRE	UL(0x0c)
+#define MAIR_ATTR_NORMAL_WT	UL(0xbb)
+
+#define MT_DEVICE_nGnRnE	0
+#define MT_DEVICE_nGnRE		1
+#define MT_DEVICE_GRE		2
+#define MT_NORMAL_NC		3
+#define MT_NORMAL		4
+#define MT_NORMAL_WT		5
+
+#define DEFAULT_MAIR_EL1							\
+	(MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) |		\
+	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) |		\
+	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) |			\
+	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) |			\
+	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) |				\
+	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT))
 
 #define MPIDR_HWID_BITMASK (0xff00fffffful)
 
@@ -92,11 +105,19 @@ enum {
 #define ESR_EC_MASK		(ESR_EC_NUM - 1)
 
 #define ESR_EC_SVC64		0x15
+#define ESR_EC_IABT		0x21
+#define ESR_EC_DABT		0x25
 #define ESR_EC_HW_BP_CURRENT	0x31
 #define ESR_EC_SSTEP_CURRENT	0x33
 #define ESR_EC_WP_CURRENT	0x35
 #define ESR_EC_BRK_INS		0x3c
 
+/* Access flag */
+#define PTE_AF			(1ULL << 10)
+
+/* Access flag update enable/disable */
+#define TCR_EL1_HA		(1ULL << 39)
+
 void aarch64_get_supported_page_sizes(uint32_t ipa,
 				      bool *ps4k, bool *ps16k, bool *ps64k);
 
@@ -109,6 +130,8 @@ void vm_install_exception_handler(struct kvm_vm *vm,
 void vm_install_sync_handler(struct kvm_vm *vm,
 		int vector, int ec, handler_fn handler);
 
+uint64_t *virt_get_pte_hva(struct kvm_vm *vm, vm_vaddr_t gva);
+
 static inline void cpu_relax(void)
 {
 	asm volatile("yield" ::: "memory");

tools/testing/selftests/kvm/include/kvm_util_base.h

@@ -34,6 +34,7 @@ struct userspace_mem_region {
 	struct sparsebit *unused_phy_pages;
 	int fd;
 	off_t offset;
+	enum vm_mem_backing_src_type backing_src_type;
 	void *host_mem;
 	void *host_alias;
 	void *mmap_start;
@@ -64,6 +65,14 @@ struct userspace_mem_regions {
 	DECLARE_HASHTABLE(slot_hash, 9);
 };
 
+enum kvm_mem_region_type {
+	MEM_REGION_CODE,
+	MEM_REGION_DATA,
+	MEM_REGION_PT,
+	MEM_REGION_TEST_DATA,
+	NR_MEM_REGIONS,
+};
+
 struct kvm_vm {
 	int mode;
 	unsigned long type;
@@ -92,6 +101,13 @@ struct kvm_vm {
 	int stats_fd;
 	struct kvm_stats_header stats_header;
 	struct kvm_stats_desc *stats_desc;
+
+	/*
+	 * KVM region slots. These are the default memslots used by page
+	 * allocators, e.g., lib/elf uses the memslots[MEM_REGION_CODE]
+	 * memslot.
+	 */
+	uint32_t memslots[NR_MEM_REGIONS];
 };
 
 
@@ -104,6 +120,13 @@ struct kvm_vm {
 struct userspace_mem_region *
 memslot2region(struct kvm_vm *vm, uint32_t memslot);
 
+static inline struct userspace_mem_region *vm_get_mem_region(struct kvm_vm *vm,
+							     enum kvm_mem_region_type type)
+{
+	assert(type < NR_MEM_REGIONS);
+	return memslot2region(vm, vm->memslots[type]);
+}
+
 /* Minimum allocated guest virtual and physical addresses */
 #define KVM_UTIL_MIN_VADDR		0x2000
 #define KVM_GUEST_PAGE_TABLE_MIN_PADDR	0x180000
@@ -384,7 +407,11 @@ void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
 void vm_mem_region_delete(struct kvm_vm *vm, uint32_t slot);
 struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id);
 vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min);
+vm_vaddr_t __vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
+			    enum kvm_mem_region_type type);
 vm_vaddr_t vm_vaddr_alloc_pages(struct kvm_vm *vm, int nr_pages);
+vm_vaddr_t __vm_vaddr_alloc_page(struct kvm_vm *vm,
+				 enum kvm_mem_region_type type);
 vm_vaddr_t vm_vaddr_alloc_page(struct kvm_vm *vm);
 
 void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
@@ -646,13 +673,13 @@ vm_paddr_t vm_alloc_page_table(struct kvm_vm *vm);
  * __vm_create() does NOT create vCPUs, @nr_runnable_vcpus is used purely to
  * calculate the amount of memory needed for per-vCPU data, e.g. stacks.
  */
-struct kvm_vm *____vm_create(enum vm_guest_mode mode, uint64_t nr_pages);
+struct kvm_vm *____vm_create(enum vm_guest_mode mode);
 struct kvm_vm *__vm_create(enum vm_guest_mode mode, uint32_t nr_runnable_vcpus,
 			   uint64_t nr_extra_pages);
 
 static inline struct kvm_vm *vm_create_barebones(void)
 {
-	return ____vm_create(VM_MODE_DEFAULT, 0);
+	return ____vm_create(VM_MODE_DEFAULT);
 }
 
 static inline struct kvm_vm *vm_create(uint32_t nr_runnable_vcpus)

tools/testing/selftests/kvm/include/userfaultfd_util.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KVM userfaultfd util
+ *
+ * Copyright (C) 2018, Red Hat, Inc.
+ * Copyright (C) 2019-2022 Google LLC
+ */
+
+#define _GNU_SOURCE /* for pipe2 */
+
+#include <inttypes.h>
+#include <time.h>
+#include <pthread.h>
+#include <linux/userfaultfd.h>
+
+#include "test_util.h"
+
+typedef int (*uffd_handler_t)(int uffd_mode, int uffd, struct uffd_msg *msg);
+
+struct uffd_desc {
+	int uffd_mode;
+	int uffd;
+	int pipefds[2];
+	useconds_t delay;
+	uffd_handler_t handler;
+	pthread_t thread;
+};
+
+struct uffd_desc *uffd_setup_demand_paging(int uffd_mode, useconds_t delay,
+					   void *hva, uint64_t len,
+					   uffd_handler_t handler);
+
+void uffd_stop_demand_paging(struct uffd_desc *uffd);
+
+#ifdef PRINT_PER_PAGE_UPDATES
+#define PER_PAGE_DEBUG(...) printf(__VA_ARGS__)
+#else
+#define PER_PAGE_DEBUG(...) _no_printf(__VA_ARGS__)
+#endif
+
+#ifdef PRINT_PER_VCPU_UPDATES
+#define PER_VCPU_DEBUG(...) printf(__VA_ARGS__)
+#else
+#define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__)
+#endif

tools/testing/selftests/kvm/lib/aarch64/processor.c

@@ -77,13 +77,15 @@ static uint64_t __maybe_unused ptrs_per_pte(struct kvm_vm *vm)
 
 void virt_arch_pgd_alloc(struct kvm_vm *vm)
 {
-	if (!vm->pgd_created) {
-		vm_paddr_t paddr = vm_phy_pages_alloc(vm,
-			page_align(vm, ptrs_per_pgd(vm) * 8) / vm->page_size,
-			KVM_GUEST_PAGE_TABLE_MIN_PADDR, 0);
-		vm->pgd = paddr;
-		vm->pgd_created = true;
-	}
+	size_t nr_pages = page_align(vm, ptrs_per_pgd(vm) * 8) / vm->page_size;
+
+	if (vm->pgd_created)
+		return;
+
+	vm->pgd = vm_phy_pages_alloc(vm, nr_pages,
+				     KVM_GUEST_PAGE_TABLE_MIN_PADDR,
+				     vm->memslots[MEM_REGION_PT]);
+	vm->pgd_created = true;
 }
 
 static void _virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
@@ -134,12 +136,12 @@ static void _virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 
 void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
 {
-	uint64_t attr_idx = 4; /* NORMAL (See DEFAULT_MAIR_EL1) */
+	uint64_t attr_idx = MT_NORMAL;
 
 	_virt_pg_map(vm, vaddr, paddr, attr_idx);
 }
 
-vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
+uint64_t *virt_get_pte_hva(struct kvm_vm *vm, vm_vaddr_t gva)
 {
 	uint64_t *ptep;
 
@@ -170,11 +172,18 @@ vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
 		TEST_FAIL("Page table levels must be 2, 3, or 4");
 	}
 
-	return pte_addr(vm, *ptep) + (gva & (vm->page_size - 1));
+	return ptep;
 
 unmapped_gva:
 	TEST_FAIL("No mapping for vm virtual address, gva: 0x%lx", gva);
-	exit(1);
+	exit(EXIT_FAILURE);
+}
+
+vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
+{
+	uint64_t *ptep = virt_get_pte_hva(vm, gva);
+
+	return pte_addr(vm, *ptep) + (gva & (vm->page_size - 1));
 }
 
 static void pte_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent, uint64_t page, int level)
@@ -319,13 +328,16 @@ void vcpu_arch_dump(FILE *stream, struct kvm_vcpu *vcpu, uint8_t indent)
 struct kvm_vcpu *aarch64_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
 				  struct kvm_vcpu_init *init, void *guest_code)
 {
-	size_t stack_size = vm->page_size == 4096 ?
-					DEFAULT_STACK_PGS * vm->page_size :
-					vm->page_size;
-	uint64_t stack_vaddr = vm_vaddr_alloc(vm, stack_size,
-					      DEFAULT_ARM64_GUEST_STACK_VADDR_MIN);
+	size_t stack_size;
+	uint64_t stack_vaddr;
 	struct kvm_vcpu *vcpu = __vm_vcpu_add(vm, vcpu_id);
 
+	stack_size = vm->page_size == 4096 ? DEFAULT_STACK_PGS * vm->page_size :
+					     vm->page_size;
+	stack_vaddr = __vm_vaddr_alloc(vm, stack_size,
+				       DEFAULT_ARM64_GUEST_STACK_VADDR_MIN,
+				       MEM_REGION_DATA);
+
 	aarch64_vcpu_setup(vcpu, init);
 
 	vcpu_set_reg(vcpu, ARM64_CORE_REG(sp_el1), stack_vaddr + stack_size);
@@ -429,8 +441,8 @@ void route_exception(struct ex_regs *regs, int vector)
 
 void vm_init_descriptor_tables(struct kvm_vm *vm)
 {
-	vm->handlers = vm_vaddr_alloc(vm, sizeof(struct handlers),
-			vm->page_size);
+	vm->handlers = __vm_vaddr_alloc(vm, sizeof(struct handlers),
+					vm->page_size, MEM_REGION_DATA);
 
 	*(vm_vaddr_t *)addr_gva2hva(vm, (vm_vaddr_t)(&exception_handlers)) = vm->handlers;
 }

tools/testing/selftests/kvm/lib/elf.c

@@ -161,7 +161,8 @@ void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename)
 		seg_vend |= vm->page_size - 1;
 		size_t seg_size = seg_vend - seg_vstart + 1;
 
-		vm_vaddr_t vaddr = vm_vaddr_alloc(vm, seg_size, seg_vstart);
+		vm_vaddr_t vaddr = __vm_vaddr_alloc(vm, seg_size, seg_vstart,
+						    MEM_REGION_CODE);
 		TEST_ASSERT(vaddr == seg_vstart, "Unable to allocate "
 			"virtual memory for segment at requested min addr,\n"
 			"  segment idx: %u\n"

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -185,13 +185,10 @@ const struct vm_guest_mode_params vm_guest_mode_params[] = {
 _Static_assert(sizeof(vm_guest_mode_params)/sizeof(struct vm_guest_mode_params) == NUM_VM_MODES,
 	       "Missing new mode params?");
 
-struct kvm_vm *____vm_create(enum vm_guest_mode mode, uint64_t nr_pages)
+struct kvm_vm *____vm_create(enum vm_guest_mode mode)
 {
 	struct kvm_vm *vm;
 
-	pr_debug("%s: mode='%s' pages='%ld'\n", __func__,
-		 vm_guest_mode_string(mode), nr_pages);
-
 	vm = calloc(1, sizeof(*vm));
 	TEST_ASSERT(vm != NULL, "Insufficient Memory");
 
@@ -287,9 +284,6 @@ struct kvm_vm *____vm_create(enum vm_guest_mode mode, uint64_t nr_pages)
 
 	/* Allocate and setup memory for guest. */
 	vm->vpages_mapped = sparsebit_alloc();
-	if (nr_pages != 0)
-		vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
-					    0, 0, nr_pages, 0);
 
 	return vm;
 }
@@ -335,8 +329,16 @@ struct kvm_vm *__vm_create(enum vm_guest_mode mode, uint32_t nr_runnable_vcpus,
 	uint64_t nr_pages = vm_nr_pages_required(mode, nr_runnable_vcpus,
 						 nr_extra_pages);
 	struct kvm_vm *vm;
+	int i;
+
+	pr_debug("%s: mode='%s' pages='%ld'\n", __func__,
+		 vm_guest_mode_string(mode), nr_pages);
 
-	vm = ____vm_create(mode, nr_pages);
+	vm = ____vm_create(mode);
+
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, 0, 0, nr_pages, 0);
+	for (i = 0; i < NR_MEM_REGIONS; i++)
+		vm->memslots[i] = 0;
 
 	kvm_vm_elf_load(vm, program_invocation_name);
 
@@ -586,6 +588,12 @@ static void __vm_mem_region_delete(struct kvm_vm *vm,
 	sparsebit_free(&region->unused_phy_pages);
 	ret = munmap(region->mmap_start, region->mmap_size);
 	TEST_ASSERT(!ret, __KVM_SYSCALL_ERROR("munmap()", ret));
+	if (region->fd >= 0) {
+		/* There's an extra map when using shared memory. */
+		ret = munmap(region->mmap_alias, region->mmap_size);
+		TEST_ASSERT(!ret, __KVM_SYSCALL_ERROR("munmap()", ret));
+		close(region->fd);
+	}
 
 	free(region);
 }
@@ -923,6 +931,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 			    vm_mem_backing_src_alias(src_type)->name);
 	}
 
+	region->backing_src_type = src_type;
 	region->unused_phy_pages = sparsebit_alloc();
 	sparsebit_set_num(region->unused_phy_pages,
 		guest_paddr >> vm->page_shift, npages);
@@ -1217,32 +1226,15 @@ static vm_vaddr_t vm_vaddr_unused_gap(struct kvm_vm *vm, size_t sz,
 	return pgidx_start * vm->page_size;
 }
 
-/*
- * VM Virtual Address Allocate
- *
- * Input Args:
- *   vm - Virtual Machine
- *   sz - Size in bytes
- *   vaddr_min - Minimum starting virtual address
- *
- * Output Args: None
- *
- * Return:
- *   Starting guest virtual address
- *
- * Allocates at least sz bytes within the virtual address space of the vm
- * given by vm.  The allocated bytes are mapped to a virtual address >=
- * the address given by vaddr_min.  Note that each allocation uses a
- * a unique set of pages, with the minimum real allocation being at least
- * a page.
- */
-vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min)
+vm_vaddr_t __vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
+			    enum kvm_mem_region_type type)
 {
 	uint64_t pages = (sz >> vm->page_shift) + ((sz % vm->page_size) != 0);
 
 	virt_pgd_alloc(vm);
 	vm_paddr_t paddr = vm_phy_pages_alloc(vm, pages,
-					      KVM_UTIL_MIN_PFN * vm->page_size, 0);
+					      KVM_UTIL_MIN_PFN * vm->page_size,
+					      vm->memslots[type]);
 
 	/*
 	 * Find an unused range of virtual page addresses of at least
@@ -1263,6 +1255,30 @@ vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min)
 	return vaddr_start;
 }
 
+/*
+ * VM Virtual Address Allocate
+ *
+ * Input Args:
+ *   vm - Virtual Machine
+ *   sz - Size in bytes
+ *   vaddr_min - Minimum starting virtual address
+ *
+ * Output Args: None
+ *
+ * Return:
+ *   Starting guest virtual address
+ *
+ * Allocates at least sz bytes within the virtual address space of the vm
+ * given by vm.  The allocated bytes are mapped to a virtual address >=
+ * the address given by vaddr_min.  Note that each allocation uses a
+ * a unique set of pages, with the minimum real allocation being at least
+ * a page. The allocated physical space comes from the TEST_DATA memory region.
+ */
+vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min)
+{
+	return __vm_vaddr_alloc(vm, sz, vaddr_min, MEM_REGION_TEST_DATA);
+}
+
 /*
  * VM Virtual Address Allocate Pages
  *
@@ -1282,6 +1298,11 @@ vm_vaddr_t vm_vaddr_alloc_pages(struct kvm_vm *vm, int nr_pages)
 	return vm_vaddr_alloc(vm, nr_pages * getpagesize(), KVM_UTIL_MIN_VADDR);
 }
 
+vm_vaddr_t __vm_vaddr_alloc_page(struct kvm_vm *vm, enum kvm_mem_region_type type)
+{
+	return __vm_vaddr_alloc(vm, getpagesize(), KVM_UTIL_MIN_VADDR, type);
+}
+
 /*
  * VM Virtual Address Allocate Page
  *
@@ -1847,7 +1868,8 @@ vm_paddr_t vm_phy_page_alloc(struct kvm_vm *vm, vm_paddr_t paddr_min,
 
 vm_paddr_t vm_alloc_page_table(struct kvm_vm *vm)
 {
-	return vm_phy_page_alloc(vm, KVM_GUEST_PAGE_TABLE_MIN_PADDR, 0);
+	return vm_phy_page_alloc(vm, KVM_GUEST_PAGE_TABLE_MIN_PADDR,
+				 vm->memslots[MEM_REGION_PT]);
 }
 
 /*

tools/testing/selftests/kvm/lib/riscv/processor.c

@@ -55,13 +55,15 @@ static uint64_t pte_index(struct kvm_vm *vm, vm_vaddr_t gva, int level)
 
 void virt_arch_pgd_alloc(struct kvm_vm *vm)
 {
-	if (!vm->pgd_created) {
-		vm_paddr_t paddr = vm_phy_pages_alloc(vm,
-			page_align(vm, ptrs_per_pte(vm) * 8) / vm->page_size,
-			KVM_GUEST_PAGE_TABLE_MIN_PADDR, 0);
-		vm->pgd = paddr;
-		vm->pgd_created = true;
-	}
+	size_t nr_pages = page_align(vm, ptrs_per_pte(vm) * 8) / vm->page_size;
+
+	if (vm->pgd_created)
+		return;
+
+	vm->pgd = vm_phy_pages_alloc(vm, nr_pages,
+				     KVM_GUEST_PAGE_TABLE_MIN_PADDR,
+				     vm->memslots[MEM_REGION_PT]);
+	vm->pgd_created = true;
 }
 
 void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
@@ -279,15 +281,18 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
 				  void *guest_code)
 {
 	int r;
-	size_t stack_size = vm->page_size == 4096 ?
-					DEFAULT_STACK_PGS * vm->page_size :
-					vm->page_size;
-	unsigned long stack_vaddr = vm_vaddr_alloc(vm, stack_size,
-					DEFAULT_RISCV_GUEST_STACK_VADDR_MIN);
+	size_t stack_size;
+	unsigned long stack_vaddr;
 	unsigned long current_gp = 0;
 	struct kvm_mp_state mps;
 	struct kvm_vcpu *vcpu;
 
+	stack_size = vm->page_size == 4096 ? DEFAULT_STACK_PGS * vm->page_size :
+					     vm->page_size;
+	stack_vaddr = __vm_vaddr_alloc(vm, stack_size,
+				       DEFAULT_RISCV_GUEST_STACK_VADDR_MIN,
+				       MEM_REGION_DATA);
+
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
 	riscv_vcpu_mmu_setup(vcpu);
 

tools/testing/selftests/kvm/lib/s390x/processor.c

@@ -21,7 +21,8 @@ void virt_arch_pgd_alloc(struct kvm_vm *vm)
 		return;
 
 	paddr = vm_phy_pages_alloc(vm, PAGES_PER_REGION,
-				   KVM_GUEST_PAGE_TABLE_MIN_PADDR, 0);
+				   KVM_GUEST_PAGE_TABLE_MIN_PADDR,
+				   vm->memslots[MEM_REGION_PT]);
 	memset(addr_gpa2hva(vm, paddr), 0xff, PAGES_PER_REGION * vm->page_size);
 
 	vm->pgd = paddr;
@@ -167,8 +168,9 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
 	TEST_ASSERT(vm->page_size == 4096, "Unsupported page size: 0x%x",
 		    vm->page_size);
 
-	stack_vaddr = vm_vaddr_alloc(vm, stack_size,
-				     DEFAULT_GUEST_STACK_VADDR_MIN);
+	stack_vaddr = __vm_vaddr_alloc(vm, stack_size,
+				       DEFAULT_GUEST_STACK_VADDR_MIN,
+				       MEM_REGION_DATA);
 
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
 

tools/testing/selftests/kvm/lib/userfaultfd_util.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KVM userfaultfd util
+ * Adapted from demand_paging_test.c
+ *
+ * Copyright (C) 2018, Red Hat, Inc.
+ * Copyright (C) 2019-2022 Google LLC
+ */
+
+#define _GNU_SOURCE /* for pipe2 */
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <poll.h>
+#include <pthread.h>
+#include <linux/userfaultfd.h>
+#include <sys/syscall.h>
+
+#include "kvm_util.h"
+#include "test_util.h"
+#include "perf_test_util.h"
+#include "userfaultfd_util.h"
+
+#ifdef __NR_userfaultfd
+
+static void *uffd_handler_thread_fn(void *arg)
+{
+	struct uffd_desc *uffd_desc = (struct uffd_desc *)arg;
+	int uffd = uffd_desc->uffd;
+	int pipefd = uffd_desc->pipefds[0];
+	useconds_t delay = uffd_desc->delay;
+	int64_t pages = 0;
+	struct timespec start;
+	struct timespec ts_diff;
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	while (1) {
+		struct uffd_msg msg;
+		struct pollfd pollfd[2];
+		char tmp_chr;
+		int r;
+
+		pollfd[0].fd = uffd;
+		pollfd[0].events = POLLIN;
+		pollfd[1].fd = pipefd;
+		pollfd[1].events = POLLIN;
+
+		r = poll(pollfd, 2, -1);
+		switch (r) {
+		case -1:
+			pr_info("poll err");
+			continue;
+		case 0:
+			continue;
+		case 1:
+			break;
+		default:
+			pr_info("Polling uffd returned %d", r);
+			return NULL;
+		}
+
+		if (pollfd[0].revents & POLLERR) {
+			pr_info("uffd revents has POLLERR");
+			return NULL;
+		}
+
+		if (pollfd[1].revents & POLLIN) {
+			r = read(pollfd[1].fd, &tmp_chr, 1);
+			TEST_ASSERT(r == 1,
+				    "Error reading pipefd in UFFD thread\n");
+			return NULL;
+		}
+
+		if (!(pollfd[0].revents & POLLIN))
+			continue;
+
+		r = read(uffd, &msg, sizeof(msg));
+		if (r == -1) {
+			if (errno == EAGAIN)
+				continue;
+			pr_info("Read of uffd got errno %d\n", errno);
+			return NULL;
+		}
+
+		if (r != sizeof(msg)) {
+			pr_info("Read on uffd returned unexpected size: %d bytes", r);
+			return NULL;
+		}
+
+		if (!(msg.event & UFFD_EVENT_PAGEFAULT))
+			continue;
+
+		if (delay)
+			usleep(delay);
+		r = uffd_desc->handler(uffd_desc->uffd_mode, uffd, &msg);
+		if (r < 0)
+			return NULL;
+		pages++;
+	}
+
+	ts_diff = timespec_elapsed(start);
+	PER_VCPU_DEBUG("userfaulted %ld pages over %ld.%.9lds. (%f/sec)\n",
+		       pages, ts_diff.tv_sec, ts_diff.tv_nsec,
+		       pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
+
+	return NULL;
+}
+
+struct uffd_desc *uffd_setup_demand_paging(int uffd_mode, useconds_t delay,
+					   void *hva, uint64_t len,
+					   uffd_handler_t handler)
+{
+	struct uffd_desc *uffd_desc;
+	bool is_minor = (uffd_mode == UFFDIO_REGISTER_MODE_MINOR);
+	int uffd;
+	struct uffdio_api uffdio_api;
+	struct uffdio_register uffdio_register;
+	uint64_t expected_ioctls = ((uint64_t) 1) << _UFFDIO_COPY;
+	int ret;
+
+	PER_PAGE_DEBUG("Userfaultfd %s mode, faults resolved with %s\n",
+		       is_minor ? "MINOR" : "MISSING",
+		       is_minor ? "UFFDIO_CONINUE" : "UFFDIO_COPY");
+
+	uffd_desc = malloc(sizeof(struct uffd_desc));
+	TEST_ASSERT(uffd_desc, "malloc failed");
+
+	/* In order to get minor faults, prefault via the alias. */
+	if (is_minor)
+		expected_ioctls = ((uint64_t) 1) << _UFFDIO_CONTINUE;
+
+	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
+	TEST_ASSERT(uffd >= 0, "uffd creation failed, errno: %d", errno);
+
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = 0;
+	TEST_ASSERT(ioctl(uffd, UFFDIO_API, &uffdio_api) != -1,
+		    "ioctl UFFDIO_API failed: %" PRIu64,
+		    (uint64_t)uffdio_api.api);
+
+	uffdio_register.range.start = (uint64_t)hva;
+	uffdio_register.range.len = len;
+	uffdio_register.mode = uffd_mode;
+	TEST_ASSERT(ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) != -1,
+		    "ioctl UFFDIO_REGISTER failed");
+	TEST_ASSERT((uffdio_register.ioctls & expected_ioctls) ==
+		    expected_ioctls, "missing userfaultfd ioctls");
+
+	ret = pipe2(uffd_desc->pipefds, O_CLOEXEC | O_NONBLOCK);
+	TEST_ASSERT(!ret, "Failed to set up pipefd");
+
+	uffd_desc->uffd_mode = uffd_mode;
+	uffd_desc->uffd = uffd;
+	uffd_desc->delay = delay;
+	uffd_desc->handler = handler;
+	pthread_create(&uffd_desc->thread, NULL, uffd_handler_thread_fn,
+		       uffd_desc);
+
+	PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n",
+		       hva, hva + len);
+
+	return uffd_desc;
+}
+
+void uffd_stop_demand_paging(struct uffd_desc *uffd)
+{
+	char c = 0;
+	int ret;
+
+	ret = write(uffd->pipefds[1], &c, 1);
+	TEST_ASSERT(ret == 1, "Unable to write to pipefd");
+
+	ret = pthread_join(uffd->thread, NULL);
+	TEST_ASSERT(ret == 0, "Pthread_join failed.");
+
+	close(uffd->uffd);
+
+	close(uffd->pipefds[1]);
+	close(uffd->pipefds[0]);
+
+	free(uffd);
+}
+
+#endif /* __NR_userfaultfd */

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -552,7 +552,7 @@ vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
 static void kvm_setup_gdt(struct kvm_vm *vm, struct kvm_dtable *dt)
 {
 	if (!vm->gdt)
-		vm->gdt = vm_vaddr_alloc_page(vm);
+		vm->gdt = __vm_vaddr_alloc_page(vm, MEM_REGION_DATA);
 
 	dt->base = vm->gdt;
 	dt->limit = getpagesize();
@@ -562,7 +562,7 @@ static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
 				int selector)
 {
 	if (!vm->tss)
-		vm->tss = vm_vaddr_alloc_page(vm);
+		vm->tss = __vm_vaddr_alloc_page(vm, MEM_REGION_DATA);
 
 	memset(segp, 0, sizeof(*segp));
 	segp->base = vm->tss;
@@ -647,8 +647,9 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
 	vm_vaddr_t stack_vaddr;
 	struct kvm_vcpu *vcpu;
 
-	stack_vaddr = vm_vaddr_alloc(vm, DEFAULT_STACK_PGS * getpagesize(),
-				     DEFAULT_GUEST_STACK_VADDR_MIN);
+	stack_vaddr = __vm_vaddr_alloc(vm, DEFAULT_STACK_PGS * getpagesize(),
+				       DEFAULT_GUEST_STACK_VADDR_MIN,
+				       MEM_REGION_DATA);
 
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
 	vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
@@ -1145,8 +1146,8 @@ void vm_init_descriptor_tables(struct kvm_vm *vm)
 	extern void *idt_handlers;
 	int i;
 
-	vm->idt = vm_vaddr_alloc_page(vm);
-	vm->handlers = vm_vaddr_alloc_page(vm);
+	vm->idt = __vm_vaddr_alloc_page(vm, MEM_REGION_DATA);
+	vm->handlers = __vm_vaddr_alloc_page(vm, MEM_REGION_DATA);
 	/* Handlers have the same address in both address spaces.*/
 	for (i = 0; i < NUM_INTERRUPTS; i++)
 		set_idt_entry(vm, i, (unsigned long)(&idt_handlers)[i], 0,