selftest: kvm: Add amx selftest

This selftest covers two aspects of AMX.  The first is triggering #NM
exception and checking the MSR XFD_ERR value.  The second case is
loading tile config and tile data into guest registers and trapping to
the host side for a complete save/load of the guest state.  TMM0
is also checked against memory data after save/restore.
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20211223145322.2914028-4-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/Makefile

@@ -82,6 +82,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/xen_shinfo_test
 TEST_GEN_PROGS_x86_64 += x86_64/xen_vmcall_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_pi_mmio_test
 TEST_GEN_PROGS_x86_64 += x86_64/sev_migrate_tests
+TEST_GEN_PROGS_x86_64 += x86_64/amx_test
 TEST_GEN_PROGS_x86_64 += demand_paging_test
 TEST_GEN_PROGS_x86_64 += dirty_log_test
 TEST_GEN_PROGS_x86_64 += dirty_log_perf_test

tools/testing/selftests/kvm/x86_64/amx_test.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * amx tests
+ *
+ * Copyright (C) 2021, Intel, Inc.
+ *
+ * Tests for amx #NM exception and save/restore.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "vmx.h"
+
+#ifndef __x86_64__
+# error This test is 64-bit only
+#endif
+
+#define VCPU_ID				0
+#define X86_FEATURE_XSAVE		(1 << 26)
+#define X86_FEATURE_OSXSAVE		(1 << 27)
+
+#define PAGE_SIZE			(1 << 12)
+#define NUM_TILES			8
+#define TILE_SIZE			1024
+#define XSAVE_SIZE			((NUM_TILES * TILE_SIZE) + PAGE_SIZE)
+
+/* Tile configuration associated: */
+#define MAX_TILES			16
+#define RESERVED_BYTES			14
+
+#define XFEATURE_XTILECFG		17
+#define XFEATURE_XTILEDATA		18
+#define XFEATURE_MASK_XTILECFG		(1 << XFEATURE_XTILECFG)
+#define XFEATURE_MASK_XTILEDATA		(1 << XFEATURE_XTILEDATA)
+#define XFEATURE_MASK_XTILE		(XFEATURE_MASK_XTILECFG | XFEATURE_MASK_XTILEDATA)
+
+#define TILE_CPUID			0x1d
+#define XSTATE_CPUID			0xd
+#define TILE_PALETTE_CPUID_SUBLEAVE	0x1
+#define XSTATE_USER_STATE_SUBLEAVE	0x0
+
+#define XSAVE_HDR_OFFSET		512
+
+struct xsave_data {
+	u8 area[XSAVE_SIZE];
+} __aligned(64);
+
+struct tile_config {
+	u8  palette_id;
+	u8  start_row;
+	u8  reserved[RESERVED_BYTES];
+	u16 colsb[MAX_TILES];
+	u8  rows[MAX_TILES];
+};
+
+struct tile_data {
+	u8 data[NUM_TILES * TILE_SIZE];
+};
+
+struct xtile_info {
+	u16 bytes_per_tile;
+	u16 bytes_per_row;
+	u16 max_names;
+	u16 max_rows;
+	u32 xsave_offset;
+	u32 xsave_size;
+};
+
+static struct xtile_info xtile;
+
+static inline u64 __xgetbv(u32 index)
+{
+	u32 eax, edx;
+
+	asm volatile("xgetbv;"
+		     : "=a" (eax), "=d" (edx)
+		     : "c" (index));
+	return eax + ((u64)edx << 32);
+}
+
+static inline void __xsetbv(u32 index, u64 value)
+{
+	u32 eax = value;
+	u32 edx = value >> 32;
+
+	asm volatile("xsetbv" :: "a" (eax), "d" (edx), "c" (index));
+}
+
+static inline void __ldtilecfg(void *cfg)
+{
+	asm volatile(".byte 0xc4,0xe2,0x78,0x49,0x00"
+		     : : "a"(cfg));
+}
+
+static inline void __tileloadd(void *tile)
+{
+	asm volatile(".byte 0xc4,0xe2,0x7b,0x4b,0x04,0x10"
+		     : : "a"(tile), "d"(0));
+}
+
+static inline void __tilerelease(void)
+{
+	asm volatile(".byte 0xc4, 0xe2, 0x78, 0x49, 0xc0" ::);
+}
+
+static inline void __xsavec(struct xsave_data *data, uint64_t rfbm)
+{
+	uint32_t rfbm_lo = rfbm;
+	uint32_t rfbm_hi = rfbm >> 32;
+
+	asm volatile("xsavec (%%rdi)"
+		     : : "D" (data), "a" (rfbm_lo), "d" (rfbm_hi)
+		     : "memory");
+}
+
+static inline void check_cpuid_xsave(void)
+{
+	uint32_t eax, ebx, ecx, edx;
+
+	eax = 1;
+	ecx = 0;
+	cpuid(&eax, &ebx, &ecx, &edx);
+	if (!(ecx & X86_FEATURE_XSAVE))
+		GUEST_ASSERT(!"cpuid: no CPU xsave support!");
+	if (!(ecx & X86_FEATURE_OSXSAVE))
+		GUEST_ASSERT(!"cpuid: no OS xsave support!");
+}
+
+static bool check_xsave_supports_xtile(void)
+{
+	return __xgetbv(0) & XFEATURE_MASK_XTILE;
+}
+
+static bool enum_xtile_config(void)
+{
+	u32 eax, ebx, ecx, edx;
+
+	eax = TILE_CPUID;
+	ecx = TILE_PALETTE_CPUID_SUBLEAVE;
+
+	cpuid(&eax, &ebx, &ecx, &edx);
+	if (!eax || !ebx || !ecx)
+		return false;
+
+	xtile.max_names = ebx >> 16;
+	if (xtile.max_names < NUM_TILES)
+		return false;
+
+	xtile.bytes_per_tile = eax >> 16;
+	if (xtile.bytes_per_tile < TILE_SIZE)
+		return false;
+
+	xtile.bytes_per_row = ebx;
+	xtile.max_rows = ecx;
+
+	return true;
+}
+
+static bool enum_xsave_tile(void)
+{
+	u32 eax, ebx, ecx, edx;
+
+	eax = XSTATE_CPUID;
+	ecx = XFEATURE_XTILEDATA;
+
+	cpuid(&eax, &ebx, &ecx, &edx);
+	if (!eax || !ebx)
+		return false;
+
+	xtile.xsave_offset = ebx;
+	xtile.xsave_size = eax;
+
+	return true;
+}
+
+static bool check_xsave_size(void)
+{
+	u32 eax, ebx, ecx, edx;
+	bool valid = false;
+
+	eax = XSTATE_CPUID;
+	ecx = XSTATE_USER_STATE_SUBLEAVE;
+
+	cpuid(&eax, &ebx, &ecx, &edx);
+	if (ebx && ebx <= XSAVE_SIZE)
+		valid = true;
+
+	return valid;
+}
+
+static bool check_xtile_info(void)
+{
+	bool ret = false;
+
+	if (!check_xsave_size())
+		return ret;
+
+	if (!enum_xsave_tile())
+		return ret;
+
+	if (!enum_xtile_config())
+		return ret;
+
+	if (sizeof(struct tile_data) >= xtile.xsave_size)
+		ret = true;
+
+	return ret;
+}
+
+static void set_tilecfg(struct tile_config *cfg)
+{
+	int i;
+
+	/* Only palette id 1 */
+	cfg->palette_id = 1;
+	for (i = 0; i < xtile.max_names; i++) {
+		cfg->colsb[i] = xtile.bytes_per_row;
+		cfg->rows[i] = xtile.max_rows;
+	}
+}
+
+static void set_xstatebv(void *data, uint64_t bv)
+{
+	*(uint64_t *)(data + XSAVE_HDR_OFFSET) = bv;
+}
+
+static u64 get_xstatebv(void *data)
+{
+	return *(u64 *)(data + XSAVE_HDR_OFFSET);
+}
+
+static void init_regs(void)
+{
+	uint64_t cr4, xcr0;
+
+	/* turn on CR4.OSXSAVE */
+	cr4 = get_cr4();
+	cr4 |= X86_CR4_OSXSAVE;
+	set_cr4(cr4);
+
+	xcr0 = __xgetbv(0);
+	xcr0 |= XFEATURE_MASK_XTILE;
+	__xsetbv(0x0, xcr0);
+}
+
+static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
+						    struct tile_data *tiledata,
+						    struct xsave_data *xsave_data)
+{
+	init_regs();
+	check_cpuid_xsave();
+	GUEST_ASSERT(check_xsave_supports_xtile());
+	GUEST_ASSERT(check_xtile_info());
+
+	/* check xtile configs */
+	GUEST_ASSERT(xtile.xsave_offset == 2816);
+	GUEST_ASSERT(xtile.xsave_size == 8192);
+	GUEST_ASSERT(xtile.max_names == 8);
+	GUEST_ASSERT(xtile.bytes_per_tile == 1024);
+	GUEST_ASSERT(xtile.bytes_per_row == 64);
+	GUEST_ASSERT(xtile.max_rows == 16);
+	GUEST_SYNC(1);
+
+	/* xfd=0, enable amx */
+	wrmsr(MSR_IA32_XFD, 0);
+	GUEST_SYNC(2);
+	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == 0);
+	set_tilecfg(amx_cfg);
+	__ldtilecfg(amx_cfg);
+	GUEST_SYNC(3);
+	/* Check save/restore when trap to userspace */
+	__tileloadd(tiledata);
+	GUEST_SYNC(4);
+	__tilerelease();
+	GUEST_SYNC(5);
+	/* bit 18 not in the XCOMP_BV after xsavec() */
+	set_xstatebv(xsave_data, XFEATURE_MASK_XTILEDATA);
+	__xsavec(xsave_data, XFEATURE_MASK_XTILEDATA);
+	GUEST_ASSERT((get_xstatebv(xsave_data) & XFEATURE_MASK_XTILEDATA) == 0);
+
+	/* xfd=0x40000, disable amx tiledata */
+	wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILEDATA);
+	GUEST_SYNC(6);
+	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILEDATA);
+	set_tilecfg(amx_cfg);
+	__ldtilecfg(amx_cfg);
+	/* Trigger #NM exception */
+	__tileloadd(tiledata);
+	GUEST_SYNC(10);
+
+	GUEST_DONE();
+}
+
+void guest_nm_handler(struct ex_regs *regs)
+{
+	/* Check if #NM is triggered by XFEATURE_MASK_XTILEDATA */
+	GUEST_SYNC(7);
+	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILEDATA);
+	GUEST_SYNC(8);
+	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILEDATA);
+	/* Clear xfd_err */
+	wrmsr(MSR_IA32_XFD_ERR, 0);
+	/* xfd=0, enable amx */
+	wrmsr(MSR_IA32_XFD, 0);
+	GUEST_SYNC(9);
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_cpuid_entry2 *entry;
+	struct kvm_regs regs1, regs2;
+	bool amx_supported = false;
+	struct kvm_vm *vm;
+	struct kvm_run *run;
+	struct kvm_x86_state *state;
+	int xsave_restore_size = 0;
+	vm_vaddr_t amx_cfg, tiledata, xsavedata;
+	struct ucall uc;
+	u32 amx_offset;
+	int stage, ret;
+
+	/* Create VM */
+	vm = vm_create_default(VCPU_ID, 0, guest_code);
+
+	entry = kvm_get_supported_cpuid_entry(1);
+	if (!(entry->ecx & X86_FEATURE_XSAVE)) {
+		print_skip("XSAVE feature not supported");
+		exit(KSFT_SKIP);
+	}
+
+	if (kvm_get_cpuid_max_basic() >= 0xd) {
+		entry = kvm_get_supported_cpuid_index(0xd, 0);
+		amx_supported = entry && !!(entry->eax & XFEATURE_MASK_XTILE);
+		if (!amx_supported) {
+			print_skip("AMX is not supported by the vCPU (eax=0x%x)", entry->eax);
+			exit(KSFT_SKIP);
+		}
+		/* Get xsave/restore max size */
+		xsave_restore_size = entry->ecx;
+	}
+
+	run = vcpu_state(vm, VCPU_ID);
+	vcpu_regs_get(vm, VCPU_ID, &regs1);
+
+	/* Register #NM handler */
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vm, VCPU_ID);
+	vm_install_exception_handler(vm, NM_VECTOR, guest_nm_handler);
+
+	/* amx cfg for guest_code */
+	amx_cfg = vm_vaddr_alloc_page(vm);
+	memset(addr_gva2hva(vm, amx_cfg), 0x0, getpagesize());
+
+	/* amx tiledata for guest_code */
+	tiledata = vm_vaddr_alloc_pages(vm, 2);
+	memset(addr_gva2hva(vm, tiledata), rand() | 1, 2 * getpagesize());
+
+	/* xsave data for guest_code */
+	xsavedata = vm_vaddr_alloc_pages(vm, 3);
+	memset(addr_gva2hva(vm, xsavedata), 0, 3 * getpagesize());
+	vcpu_args_set(vm, VCPU_ID, 3, amx_cfg, tiledata, xsavedata);
+
+	for (stage = 1; ; stage++) {
+		_vcpu_run(vm, VCPU_ID);
+		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+			    "Stage %d: unexpected exit reason: %u (%s),\n",
+			    stage, run->exit_reason,
+			    exit_reason_str(run->exit_reason));
+
+		switch (get_ucall(vm, VCPU_ID, &uc)) {
+		case UCALL_ABORT:
+			TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
+				  __FILE__, uc.args[1]);
+			/* NOT REACHED */
+		case UCALL_SYNC:
+			switch (uc.args[1]) {
+			case 1:
+			case 2:
+			case 3:
+			case 5:
+			case 6:
+			case 7:
+			case 8:
+				fprintf(stderr, "GUEST_SYNC(%ld)\n", uc.args[1]);
+				break;
+			case 4:
+			case 10:
+				fprintf(stderr,
+				"GUEST_SYNC(%ld), check save/restore status\n", uc.args[1]);
+
+				/* Compacted mode, get amx offset by xsave area
+				 * size subtract 8K amx size.
+				 */
+				amx_offset = xsave_restore_size - NUM_TILES*TILE_SIZE;
+				state = vcpu_save_state(vm, VCPU_ID);
+				void *amx_start = (void *)state->xsave + amx_offset;
+				void *tiles_data = (void *)addr_gva2hva(vm, tiledata);
+				/* Only check TMM0 register, 1 tile */
+				ret = memcmp(amx_start, tiles_data, TILE_SIZE);
+				TEST_ASSERT(ret == 0, "memcmp failed, ret=%d\n", ret);
+				kvm_x86_state_cleanup(state);
+				break;
+			case 9:
+				fprintf(stderr,
+				"GUEST_SYNC(%ld), #NM exception and enable amx\n", uc.args[1]);
+				break;
+			}
+			break;
+		case UCALL_DONE:
+			fprintf(stderr, "UCALL_DONE\n");
+			goto done;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		}
+
+		state = vcpu_save_state(vm, VCPU_ID);
+		memset(&regs1, 0, sizeof(regs1));
+		vcpu_regs_get(vm, VCPU_ID, &regs1);
+
+		kvm_vm_release(vm);
+
+		/* Restore state in a new VM.  */
+		kvm_vm_restart(vm, O_RDWR);
+		vm_vcpu_add(vm, VCPU_ID);
+		vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+		vcpu_load_state(vm, VCPU_ID, state);
+		run = vcpu_state(vm, VCPU_ID);
+		kvm_x86_state_cleanup(state);
+
+		memset(&regs2, 0, sizeof(regs2));
+		vcpu_regs_get(vm, VCPU_ID, &regs2);
+		TEST_ASSERT(!memcmp(&regs1, &regs2, sizeof(regs2)),
+			    "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
+			    (ulong) regs2.rdi, (ulong) regs2.rsi);
+	}
+done:
+	kvm_vm_free(vm);
+}