Commit 0581dfba authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: selftests: Add a testcase for disabling feature MSRs init quirk 

Expand and rename the feature MSRs test to verify KVM's ABI and quirk
for initializing feature MSRs.

Exempt VM_CR{0,4}_FIXED1 from most tests as KVM intentionally takes full
control of the MSRs, e.g. to prevent L1 from running L2 with bogus CR0
and/or CR4 values.

Link: https://lore.kernel.org/r/20240802185511.305849-10-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent b799e3e7

tools/testing/selftests/kvm/Makefile

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@@ -67,7 +67,7 @@ TEST_PROGS_x86_64 += x86_64/nx_huge_pages_test.sh 
TEST_GEN_PROGS_x86_64 = x86_64/cpuid_test

TEST_GEN_PROGS_x86_64 += x86_64/cr4_cpuid_sync_test

TEST_GEN_PROGS_x86_64 += x86_64/dirty_log_page_splitting_test

TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features

TEST_GEN_PROGS_x86_64 += x86_64/feature_msrs_test

TEST_GEN_PROGS_x86_64 += x86_64/exit_on_emulation_failure_test

TEST_GEN_PROGS_x86_64 += x86_64/fix_hypercall_test

TEST_GEN_PROGS_x86_64 += x86_64/hwcr_msr_test

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

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// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (C) 2020, Red Hat, Inc.

 */

#include <fcntl.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/ioctl.h>



#include "test_util.h"

#include "kvm_util.h"

#include "processor.h"



static bool is_kvm_controlled_msr(uint32_t msr)

{

	return msr == MSR_IA32_VMX_CR0_FIXED1 || msr == MSR_IA32_VMX_CR4_FIXED1;

}



/*

 * For VMX MSRs with a "true" variant, KVM requires userspace to set the "true"

 * MSR, and doesn't allow setting the hidden version.

 */

static bool is_hidden_vmx_msr(uint32_t msr)

{

	switch (msr) {

	case MSR_IA32_VMX_PINBASED_CTLS:

	case MSR_IA32_VMX_PROCBASED_CTLS:

	case MSR_IA32_VMX_EXIT_CTLS:

	case MSR_IA32_VMX_ENTRY_CTLS:

		return true;

	default:

		return false;

	}

}



static bool is_quirked_msr(uint32_t msr)

{

	return msr != MSR_AMD64_DE_CFG;

}



static void test_feature_msr(uint32_t msr)

{

	const uint64_t supported_mask = kvm_get_feature_msr(msr);

	uint64_t reset_value = is_quirked_msr(msr) ? supported_mask : 0;

	struct kvm_vcpu *vcpu;

	struct kvm_vm *vm;



	/*

	 * Don't bother testing KVM-controlled MSRs beyond verifying that the

	 * MSR can be read from userspace.  Any value is effectively legal, as

	 * KVM is bound by x86 architecture, not by ABI.

	 */

	if (is_kvm_controlled_msr(msr))

		return;



	/*

	 * More goofy behavior.  KVM reports the host CPU's actual revision ID,

	 * but initializes the vCPU's revision ID to an arbitrary value.

	 */

	if (msr == MSR_IA32_UCODE_REV)

		reset_value = host_cpu_is_intel ? 0x100000000ULL : 0x01000065;



	/*

	 * For quirked MSRs, KVM's ABI is to initialize the vCPU's value to the

	 * full set of features supported by KVM.  For non-quirked MSRs, and

	 * when the quirk is disabled, KVM must zero-initialize the MSR and let

	 * userspace do the configuration.

	 */

	vm = vm_create_with_one_vcpu(&vcpu, NULL);

	TEST_ASSERT(vcpu_get_msr(vcpu, msr) == reset_value,

		    "Wanted 0x%lx for %squirked MSR 0x%x, got 0x%lx",

		    reset_value, is_quirked_msr(msr) ? "" : "non-", msr,

		    vcpu_get_msr(vcpu, msr));

	if (!is_hidden_vmx_msr(msr))

		vcpu_set_msr(vcpu, msr, supported_mask);

	kvm_vm_free(vm);



	if (is_hidden_vmx_msr(msr))

		return;



	if (!kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2) ||

	    !(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_STUFF_FEATURE_MSRS))

		return;



	vm = vm_create(1);

	vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, KVM_X86_QUIRK_STUFF_FEATURE_MSRS);



	vcpu = vm_vcpu_add(vm, 0, NULL);

	TEST_ASSERT(!vcpu_get_msr(vcpu, msr),

		    "Quirk disabled, wanted '0' for MSR 0x%x, got 0x%lx",

		    msr, vcpu_get_msr(vcpu, msr));

	kvm_vm_free(vm);

}



int main(int argc, char *argv[])

{

	const struct kvm_msr_list *feature_list;

	int i;



	/*

	 * Skip the entire test if MSR_FEATURES isn't supported, other tests

	 * will cover the "regular" list of MSRs, the coverage here is purely

	 * opportunistic and not interesting on its own.

	 */

	TEST_REQUIRE(kvm_has_cap(KVM_CAP_GET_MSR_FEATURES));



	(void)kvm_get_msr_index_list();



	feature_list = kvm_get_feature_msr_index_list();

	for (i = 0; i < feature_list->nmsrs; i++)

		test_feature_msr(feature_list->indices[i]);

}

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

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// SPDX-License-Identifier: GPL-2.0

/*

 * Test that KVM_GET_MSR_INDEX_LIST and

 * KVM_GET_MSR_FEATURE_INDEX_LIST work as intended

 *

 * Copyright (C) 2020, Red Hat, Inc.

 */

#include <fcntl.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/ioctl.h>



#include "test_util.h"

#include "kvm_util.h"

#include "processor.h"



int main(int argc, char *argv[])

{

	const struct kvm_msr_list *feature_list;

	int i;



	/*

	 * Skip the entire test if MSR_FEATURES isn't supported, other tests

	 * will cover the "regular" list of MSRs, the coverage here is purely

	 * opportunistic and not interesting on its own.

	 */

	TEST_REQUIRE(kvm_has_cap(KVM_CAP_GET_MSR_FEATURES));



	(void)kvm_get_msr_index_list();



	feature_list = kvm_get_feature_msr_index_list();

	for (i = 0; i < feature_list->nmsrs; i++)

		kvm_get_feature_msr(feature_list->indices[i]);

}