KVM: selftests: Remove the obsolete/dead MMU role test

Remove the MMU role test, which was made obsolete by KVM commit
feb627e8 ("KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN").  The
ongoing costs of keeping the test updated far outweigh any benefits,
e.g. the test _might_ be useful as an example or for documentation
purposes, but otherwise the test is dead weight.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220614200707.3315957-14-seanjc@google.com

tools/testing/selftests/kvm/.gitignore

@@ -27,7 +27,6 @@
 /x86_64/hyperv_svm_test
 /x86_64/max_vcpuid_cap_test
 /x86_64/mmio_warning_test
-/x86_64/mmu_role_test
 /x86_64/monitor_mwait_test
 /x86_64/nx_huge_pages_test
 /x86_64/platform_info_test

tools/testing/selftests/kvm/Makefile

@@ -87,7 +87,6 @@ TEST_GEN_PROGS_x86_64 += x86_64/hyperv_svm_test
 TEST_GEN_PROGS_x86_64 += x86_64/kvm_clock_test
 TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
 TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
-TEST_GEN_PROGS_x86_64 += x86_64/mmu_role_test
 TEST_GEN_PROGS_x86_64 += x86_64/monitor_mwait_test
 TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
 TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -142,9 +142,6 @@ struct kvm_x86_cpu_feature {
 #define CPUID_XSAVE		(1ul << 26)
 #define CPUID_OSXSAVE		(1ul << 27)
 
-/* CPUID.0x8000_0001.EDX */
-#define CPUID_GBPAGES		(1ul << 26)
-
 /* CPUID.0x8000_000A.EDX */
 #define CPUID_NRIPS		BIT(3)
 

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

-// SPDX-License-Identifier: GPL-2.0
-
-#include "kvm_util.h"
-#include "processor.h"
-
-#define MMIO_GPA	0x100000000ull
-
-static void guest_code(void)
-{
-	(void)READ_ONCE(*((uint64_t *)MMIO_GPA));
-	(void)READ_ONCE(*((uint64_t *)MMIO_GPA));
-
-	GUEST_ASSERT(0);
-}
-
-static void guest_pf_handler(struct ex_regs *regs)
-{
-	/* PFEC == RSVD | PRESENT (read, kernel). */
-	GUEST_ASSERT(regs->error_code == 0x9);
-	GUEST_DONE();
-}
-
-static void mmu_role_test(u32 *cpuid_reg, u32 evil_cpuid_val)
-{
-	u32 good_cpuid_val = *cpuid_reg;
-	struct kvm_vcpu *vcpu;
-	struct kvm_run *run;
-	struct kvm_vm *vm;
-	uint64_t cmd;
-
-	/* Create VM */
-	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
-	run = vcpu->run;
-
-	/* Map 1gb page without a backing memlot. */
-	__virt_pg_map(vm, MMIO_GPA, MMIO_GPA, PG_LEVEL_1G);
-
-	vcpu_run(vcpu);
-
-	/* Guest access to the 1gb page should trigger MMIO. */
-	TEST_ASSERT(run->exit_reason == KVM_EXIT_MMIO,
-		    "Unexpected exit reason: %u (%s), expected MMIO exit (1gb page w/o memslot)\n",
-		    run->exit_reason, exit_reason_str(run->exit_reason));
-
-	TEST_ASSERT(run->mmio.len == 8, "Unexpected exit mmio size = %u", run->mmio.len);
-
-	TEST_ASSERT(run->mmio.phys_addr == MMIO_GPA,
-		    "Unexpected exit mmio address = 0x%llx", run->mmio.phys_addr);
-
-	/*
-	 * Effect the CPUID change for the guest and re-enter the guest.  Its
-	 * access should now #PF due to the PAGE_SIZE bit being reserved or
-	 * the resulting GPA being invalid.  Note, kvm_get_supported_cpuid()
-	 * returns the struct that contains the entry being modified.  Eww.
-	 */
-	*cpuid_reg = evil_cpuid_val;
-	vcpu_set_cpuid(vcpu, kvm_get_supported_cpuid());
-
-	/*
-	 * Add a dummy memslot to coerce KVM into bumping the MMIO generation.
-	 * KVM does not "officially" support mucking with CPUID after KVM_RUN,
-	 * and will incorrectly reuse MMIO SPTEs.  Don't delete the memslot!
-	 * KVM x86 zaps all shadow pages on memslot deletion.
-	 */
-	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
-				    MMIO_GPA << 1, 10, 1, 0);
-
-	/* Set up a #PF handler to eat the RSVD #PF and signal all done! */
-	vm_init_descriptor_tables(vm);
-	vcpu_init_descriptor_tables(vcpu);
-	vm_install_exception_handler(vm, PF_VECTOR, guest_pf_handler);
-
-	vcpu_run(vcpu);
-
-	cmd = get_ucall(vcpu, NULL);
-	TEST_ASSERT(cmd == UCALL_DONE,
-		    "Unexpected guest exit, exit_reason=%s, ucall.cmd = %lu\n",
-		    exit_reason_str(run->exit_reason), cmd);
-
-	/*
-	 * Restore the happy CPUID value for the next test.  Yes, changes are
-	 * indeed persistent across VM destruction.
-	 */
-	*cpuid_reg = good_cpuid_val;
-
-	kvm_vm_free(vm);
-}
-
-int main(int argc, char *argv[])
-{
-	struct kvm_cpuid_entry2 *entry;
-	int opt;
-
-	/*
-	 * All tests are opt-in because TDP doesn't play nice with reserved #PF
-	 * in the GVA->GPA translation.  The hardware page walker doesn't let
-	 * software change GBPAGES or MAXPHYADDR, and KVM doesn't manually walk
-	 * the GVA on fault for performance reasons.
-	 */
-	bool do_gbpages = false;
-	bool do_maxphyaddr = false;
-
-	setbuf(stdout, NULL);
-
-	while ((opt = getopt(argc, argv, "gm")) != -1) {
-		switch (opt) {
-		case 'g':
-			do_gbpages = true;
-			break;
-		case 'm':
-			do_maxphyaddr = true;
-			break;
-		case 'h':
-		default:
-			printf("usage: %s [-g (GBPAGES)] [-m (MAXPHYADDR)]\n", argv[0]);
-			break;
-		}
-	}
-
-	__TEST_REQUIRE(do_gbpages || do_maxphyaddr, "No sub-tests selected");
-
-	entry = kvm_get_supported_cpuid_entry(0x80000001);
-	TEST_REQUIRE(entry->edx & CPUID_GBPAGES);
-
-	if (do_gbpages) {
-		pr_info("Test MMIO after toggling CPUID.GBPAGES\n\n");
-		mmu_role_test(&entry->edx, entry->edx & ~CPUID_GBPAGES);
-	}
-
-	if (do_maxphyaddr) {
-		pr_info("Test MMIO after changing CPUID.MAXPHYADDR\n\n");
-		entry = kvm_get_supported_cpuid_entry(0x80000008);
-		mmu_role_test(&entry->eax, (entry->eax & ~0xff) | 0x20);
-	}
-
-	return 0;
-}