tools/testing/selftests/kvm/x86/nested_set_state_test.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2019, Google LLC.
 *
 * This test verifies the integrity of calling the ioctl KVM_SET_NESTED_STATE.
 */

#include "test_util.h"
#include "kvm_util.h"
#include "processor.h"
#include "vmx.h"
#include "svm_util.h"

#include <errno.h>
#include <linux/kvm.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>

/*
 * Mirror of VMCS12_REVISION in arch/x86/kvm/vmx/vmcs12.h. If that value
 * changes this should be updated.
 */
#define VMCS12_REVISION 0x11e57ed0

bool have_evmcs;

void test_nested_state(struct kvm_vcpu *vcpu, struct kvm_nested_state *state)
{
	vcpu_nested_state_set(vcpu, state);
}

void test_nested_state_expect_errno(struct kvm_vcpu *vcpu,
				    struct kvm_nested_state *state,
				    int expected_errno)
{
	int rv;

	rv = __vcpu_nested_state_set(vcpu, state);
	TEST_ASSERT(rv == -1 && errno == expected_errno,
		"Expected %s (%d) from vcpu_nested_state_set but got rv: %i errno: %s (%d)",
		strerror(expected_errno), expected_errno, rv, strerror(errno),
		errno);
}

void test_nested_state_expect_einval(struct kvm_vcpu *vcpu,
				     struct kvm_nested_state *state)
{
	test_nested_state_expect_errno(vcpu, state, EINVAL);
}

void test_nested_state_expect_efault(struct kvm_vcpu *vcpu,
				     struct kvm_nested_state *state)
{
	test_nested_state_expect_errno(vcpu, state, EFAULT);
}

void set_revision_id_for_vmcs12(struct kvm_nested_state *state,
				u32 vmcs12_revision)
{
	/* Set revision_id in vmcs12 to vmcs12_revision. */
	memcpy(&state->data, &vmcs12_revision, sizeof(u32));
}

void set_default_state(struct kvm_nested_state *state)
{
	memset(state, 0, sizeof(*state));
	state->flags = KVM_STATE_NESTED_RUN_PENDING |
		       KVM_STATE_NESTED_GUEST_MODE;
	state->format = 0;
	state->size = sizeof(*state);
}

void set_default_vmx_state(struct kvm_nested_state *state, int size)
{
	memset(state, 0, size);
	if (have_evmcs)
		state->flags = KVM_STATE_NESTED_EVMCS;
	state->format = 0;
	state->size = size;
	state->hdr.vmx.vmxon_pa = 0x1000;
	state->hdr.vmx.vmcs12_pa = 0x2000;
	state->hdr.vmx.smm.flags = 0;
	set_revision_id_for_vmcs12(state, VMCS12_REVISION);
}

void test_vmx_nested_state(struct kvm_vcpu *vcpu)
{
	/* Add a page for VMCS12. */
	const int state_sz = sizeof(struct kvm_nested_state) + getpagesize();
	struct kvm_nested_state *state =
		(struct kvm_nested_state *)malloc(state_sz);

	/* The format must be set to 0. 0 for VMX, 1 for SVM. */
	set_default_vmx_state(state, state_sz);
	state->format = 1;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * We cannot virtualize anything if the guest does not have VMX
	 * enabled.
	 */
	set_default_vmx_state(state, state_sz);
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * We cannot virtualize anything if the guest does not have VMX
	 * enabled.  We expect KVM_SET_NESTED_STATE to return 0 if vmxon_pa
	 * is set to -1ull, but the flags must be zero.
	 */
	set_default_vmx_state(state, state_sz);
	state->hdr.vmx.vmxon_pa = -1ull;
	test_nested_state_expect_einval(vcpu, state);

	state->hdr.vmx.vmcs12_pa = -1ull;
	state->flags = KVM_STATE_NESTED_EVMCS;
	test_nested_state_expect_einval(vcpu, state);

	state->flags = 0;
	test_nested_state(vcpu, state);

	/* Enable VMX in the guest CPUID. */
	vcpu_set_cpuid_feature(vcpu, X86_FEATURE_VMX);

	/*
	 * Setting vmxon_pa == -1ull and vmcs_pa == -1ull exits early without
	 * setting the nested state. When the eVMCS flag is not set, the
	 * expected return value is '0'.
	 */
	set_default_vmx_state(state, state_sz);
	state->flags = 0;
	state->hdr.vmx.vmxon_pa = -1ull;
	state->hdr.vmx.vmcs12_pa = -1ull;
	test_nested_state(vcpu, state);

	/*
	 * When eVMCS is supported, the eVMCS flag can only be set if the
	 * enlightened VMCS capability has been enabled.
	 */
	if (have_evmcs) {
		state->flags = KVM_STATE_NESTED_EVMCS;
		test_nested_state_expect_einval(vcpu, state);
		vcpu_enable_evmcs(vcpu);
		test_nested_state(vcpu, state);
	}

	/* It is invalid to have vmxon_pa == -1ull and SMM flags non-zero. */
	state->hdr.vmx.smm.flags = 1;
	test_nested_state_expect_einval(vcpu, state);

	/* Invalid flags are rejected. */
	set_default_vmx_state(state, state_sz);
	state->hdr.vmx.flags = ~0;
	test_nested_state_expect_einval(vcpu, state);

	/* It is invalid to have vmxon_pa == -1ull and vmcs_pa != -1ull. */
	set_default_vmx_state(state, state_sz);
	state->hdr.vmx.vmxon_pa = -1ull;
	state->flags = 0;
	test_nested_state_expect_einval(vcpu, state);

	/* It is invalid to have vmxon_pa set to a non-page aligned address. */
	set_default_vmx_state(state, state_sz);
	state->hdr.vmx.vmxon_pa = 1;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * It is invalid to have KVM_STATE_NESTED_SMM_GUEST_MODE and
	 * KVM_STATE_NESTED_GUEST_MODE set together.
	 */
	set_default_vmx_state(state, state_sz);
	state->flags = KVM_STATE_NESTED_GUEST_MODE  |
		      KVM_STATE_NESTED_RUN_PENDING;
	state->hdr.vmx.smm.flags = KVM_STATE_NESTED_SMM_GUEST_MODE;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * It is invalid to have any of the SMM flags set besides:
	 *	KVM_STATE_NESTED_SMM_GUEST_MODE
	 *	KVM_STATE_NESTED_SMM_VMXON
	 */
	set_default_vmx_state(state, state_sz);
	state->hdr.vmx.smm.flags = ~(KVM_STATE_NESTED_SMM_GUEST_MODE |
				KVM_STATE_NESTED_SMM_VMXON);
	test_nested_state_expect_einval(vcpu, state);

	/* Outside SMM, SMM flags must be zero. */
	set_default_vmx_state(state, state_sz);
	state->flags = 0;
	state->hdr.vmx.smm.flags = KVM_STATE_NESTED_SMM_GUEST_MODE;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * Size must be large enough to fit kvm_nested_state and vmcs12
	 * if VMCS12 physical address is set
	 */
	set_default_vmx_state(state, state_sz);
	state->size = sizeof(*state);
	state->flags = 0;
	test_nested_state_expect_einval(vcpu, state);

	set_default_vmx_state(state, state_sz);
	state->size = sizeof(*state);
	state->flags = 0;
	state->hdr.vmx.vmcs12_pa = -1;
	test_nested_state(vcpu, state);

	/*
	 * KVM_SET_NESTED_STATE succeeds with invalid VMCS
	 * contents but L2 not running.
	 */
	set_default_vmx_state(state, state_sz);
	state->flags = 0;
	test_nested_state(vcpu, state);

	/* Invalid flags are rejected, even if no VMCS loaded. */
	set_default_vmx_state(state, state_sz);
	state->size = sizeof(*state);
	state->flags = 0;
	state->hdr.vmx.vmcs12_pa = -1;
	state->hdr.vmx.flags = ~0;
	test_nested_state_expect_einval(vcpu, state);

	/* vmxon_pa cannot be the same address as vmcs_pa. */
	set_default_vmx_state(state, state_sz);
	state->hdr.vmx.vmxon_pa = 0;
	state->hdr.vmx.vmcs12_pa = 0;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * Test that if we leave nesting the state reflects that when we get
	 * it again.
	 */
	set_default_vmx_state(state, state_sz);
	state->hdr.vmx.vmxon_pa = -1ull;
	state->hdr.vmx.vmcs12_pa = -1ull;
	state->flags = 0;
	test_nested_state(vcpu, state);
	vcpu_nested_state_get(vcpu, state);
	TEST_ASSERT(state->size >= sizeof(*state) && state->size <= state_sz,
		    "Size must be between %ld and %d.  The size returned was %d.",
		    sizeof(*state), state_sz, state->size);

	TEST_ASSERT_EQ(state->hdr.vmx.vmxon_pa, -1ull);
	TEST_ASSERT_EQ(state->hdr.vmx.vmcs12_pa, -1ull);
	TEST_ASSERT_EQ(state->flags, 0);

	free(state);
}

static void vcpu_efer_enable_svm(struct kvm_vcpu *vcpu)
{
	u64 old_efer = vcpu_get_msr(vcpu, MSR_EFER);

	vcpu_set_msr(vcpu, MSR_EFER, old_efer | EFER_SVME);
}

static void vcpu_efer_disable_svm(struct kvm_vcpu *vcpu)
{
	u64 old_efer = vcpu_get_msr(vcpu, MSR_EFER);

	vcpu_set_msr(vcpu, MSR_EFER, old_efer & ~EFER_SVME);
}

void set_default_svm_state(struct kvm_nested_state *state, int size)
{
	memset(state, 0, size);
	state->format = 1;
	state->size = size;
	state->hdr.svm.vmcb_pa = 0x3000;
}

void test_svm_nested_state(struct kvm_vcpu *vcpu)
{
	/* Add a page for VMCB. */
	const int state_sz = sizeof(struct kvm_nested_state) + getpagesize();
	struct kvm_nested_state *state =
		(struct kvm_nested_state *)malloc(state_sz);

	vcpu_set_cpuid_feature(vcpu, X86_FEATURE_SVM);

	/* The format must be set to 1. 0 for VMX, 1 for SVM. */
	set_default_svm_state(state, state_sz);
	state->format = 0;
	test_nested_state_expect_einval(vcpu, state);

	/* Invalid flags are rejected, KVM_STATE_NESTED_EVMCS is VMX-only  */
	set_default_svm_state(state, state_sz);
	state->flags = KVM_STATE_NESTED_EVMCS;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * If EFER.SVME is clear, guest mode is disallowed and GIF can be set or
	 * cleared.
	 */
	vcpu_efer_disable_svm(vcpu);

	set_default_svm_state(state, state_sz);
	state->flags = KVM_STATE_NESTED_GUEST_MODE;
	test_nested_state_expect_einval(vcpu, state);

	state->flags = 0;
	test_nested_state(vcpu, state);

	state->flags = KVM_STATE_NESTED_GIF_SET;
	test_nested_state(vcpu, state);

	/* Enable SVM in the guest EFER. */
	vcpu_efer_enable_svm(vcpu);

	/* Setting vmcb_pa to a non-aligned address is only fine when not entering guest mode */
	set_default_svm_state(state, state_sz);
	state->hdr.svm.vmcb_pa = -1ull;
	state->flags = 0;
	test_nested_state(vcpu, state);
	state->flags = KVM_STATE_NESTED_GUEST_MODE;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * Size must be large enough to fit kvm_nested_state and VMCB
	 * only when entering guest mode.
	 */
	set_default_svm_state(state, state_sz/2);
	state->flags = 0;
	test_nested_state(vcpu, state);
	state->flags = KVM_STATE_NESTED_GUEST_MODE;
	test_nested_state_expect_einval(vcpu, state);

	/*
	 * Test that if we leave nesting the state reflects that when we get it
	 * again, except for vmcb_pa, which is always returned as 0 when not in
	 * guest mode.
	 */
	set_default_svm_state(state, state_sz);
	state->hdr.svm.vmcb_pa = -1ull;
	state->flags = KVM_STATE_NESTED_GIF_SET;
	test_nested_state(vcpu, state);
	vcpu_nested_state_get(vcpu, state);
	TEST_ASSERT(state->size >= sizeof(*state) && state->size <= state_sz,
		    "Size must be between %ld and %d.  The size returned was %d.",
		    sizeof(*state), state_sz, state->size);

	TEST_ASSERT_EQ(state->hdr.svm.vmcb_pa, 0);
	TEST_ASSERT_EQ(state->flags, KVM_STATE_NESTED_GIF_SET);

	free(state);
}

int main(int argc, char *argv[])
{
	struct kvm_vm *vm;
	struct kvm_nested_state state;
	struct kvm_vcpu *vcpu;

	have_evmcs = kvm_check_cap(KVM_CAP_HYPERV_ENLIGHTENED_VMCS);

	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX) ||
		     kvm_cpu_has(X86_FEATURE_SVM));
	TEST_REQUIRE(kvm_has_cap(KVM_CAP_NESTED_STATE));

	vm = vm_create_with_one_vcpu(&vcpu, NULL);

	/*
	 * First run tests with VMX/SVM disabled to check error handling.
	 * test_{vmx/svm}_nested_state() will re-enable as needed.
	 */
	if (kvm_cpu_has(X86_FEATURE_VMX))
		vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_VMX);
	else
		vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_SVM);

	/* Passing a NULL kvm_nested_state causes a EFAULT. */
	test_nested_state_expect_efault(vcpu, NULL);

	/* 'size' cannot be smaller than sizeof(kvm_nested_state). */
	set_default_state(&state);
	state.size = 0;
	test_nested_state_expect_einval(vcpu, &state);

	/*
	 * Setting the flags 0xf fails the flags check.  The only flags that
	 * can be used are:
	 *     KVM_STATE_NESTED_GUEST_MODE
	 *     KVM_STATE_NESTED_RUN_PENDING
	 *     KVM_STATE_NESTED_EVMCS
	 */
	set_default_state(&state);
	state.flags = 0xf;
	test_nested_state_expect_einval(vcpu, &state);

	/*
	 * If KVM_STATE_NESTED_RUN_PENDING is set then
	 * KVM_STATE_NESTED_GUEST_MODE has to be set as well.
	 */
	set_default_state(&state);
	state.flags = KVM_STATE_NESTED_RUN_PENDING;
	test_nested_state_expect_einval(vcpu, &state);

	if (kvm_cpu_has(X86_FEATURE_VMX))
		test_vmx_nested_state(vcpu);
	else
		test_svm_nested_state(vcpu);

	kvm_vm_free(vm);
	return 0;
}