Commit b046f4ee authored by Sean Christopherson's avatar Sean Christopherson
Browse files

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: default avatarSean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220614200707.3315957-14-seanjc@google.com
parent 045520e4

tools/testing/selftests/kvm/.gitignore

+0 −1
Original line number Diff line number Diff line
@@ -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

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Original line number Diff line number Diff line
@@ -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

+0 −3
Original line number Diff line number Diff line
@@ -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

deleted100644 → 0
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Original line number Diff line number Diff line 
// 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;

}