feature_msrs_test.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2020, Red Hat, Inc.
  4 */
  5#include <fcntl.h>
  6#include <stdio.h>
  7#include <stdlib.h>
  8#include <string.h>
  9#include <sys/ioctl.h>
 10
 11#include "test_util.h"
 12#include "kvm_util.h"
 13#include "processor.h"
 14
 15static bool is_kvm_controlled_msr(uint32_t msr)
 16{
 17	return msr == MSR_IA32_VMX_CR0_FIXED1 || msr == MSR_IA32_VMX_CR4_FIXED1;
 18}
 19
 20/*
 21 * For VMX MSRs with a "true" variant, KVM requires userspace to set the "true"
 22 * MSR, and doesn't allow setting the hidden version.
 23 */
 24static bool is_hidden_vmx_msr(uint32_t msr)
 25{
 26	switch (msr) {
 27	case MSR_IA32_VMX_PINBASED_CTLS:
 28	case MSR_IA32_VMX_PROCBASED_CTLS:
 29	case MSR_IA32_VMX_EXIT_CTLS:
 30	case MSR_IA32_VMX_ENTRY_CTLS:
 31		return true;
 32	default:
 33		return false;
 34	}
 35}
 36
 37static bool is_quirked_msr(uint32_t msr)
 38{
 39	return msr != MSR_AMD64_DE_CFG;
 40}
 41
 42static void test_feature_msr(uint32_t msr)
 43{
 44	const uint64_t supported_mask = kvm_get_feature_msr(msr);
 45	uint64_t reset_value = is_quirked_msr(msr) ? supported_mask : 0;
 46	struct kvm_vcpu *vcpu;
 47	struct kvm_vm *vm;
 48
 49	/*
 50	 * Don't bother testing KVM-controlled MSRs beyond verifying that the
 51	 * MSR can be read from userspace.  Any value is effectively legal, as
 52	 * KVM is bound by x86 architecture, not by ABI.
 53	 */
 54	if (is_kvm_controlled_msr(msr))
 55		return;
 56
 57	/*
 58	 * More goofy behavior.  KVM reports the host CPU's actual revision ID,
 59	 * but initializes the vCPU's revision ID to an arbitrary value.
 60	 */
 61	if (msr == MSR_IA32_UCODE_REV)
 62		reset_value = host_cpu_is_intel ? 0x100000000ULL : 0x01000065;
 63
 64	/*
 65	 * For quirked MSRs, KVM's ABI is to initialize the vCPU's value to the
 66	 * full set of features supported by KVM.  For non-quirked MSRs, and
 67	 * when the quirk is disabled, KVM must zero-initialize the MSR and let
 68	 * userspace do the configuration.
 69	 */
 70	vm = vm_create_with_one_vcpu(&vcpu, NULL);
 71	TEST_ASSERT(vcpu_get_msr(vcpu, msr) == reset_value,
 72		    "Wanted 0x%lx for %squirked MSR 0x%x, got 0x%lx",
 73		    reset_value, is_quirked_msr(msr) ? "" : "non-", msr,
 74		    vcpu_get_msr(vcpu, msr));
 75	if (!is_hidden_vmx_msr(msr))
 76		vcpu_set_msr(vcpu, msr, supported_mask);
 77	kvm_vm_free(vm);
 78
 79	if (is_hidden_vmx_msr(msr))
 80		return;
 81
 82	if (!kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2) ||
 83	    !(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & KVM_X86_QUIRK_STUFF_FEATURE_MSRS))
 84		return;
 85
 86	vm = vm_create(1);
 87	vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, KVM_X86_QUIRK_STUFF_FEATURE_MSRS);
 88
 89	vcpu = vm_vcpu_add(vm, 0, NULL);
 90	TEST_ASSERT(!vcpu_get_msr(vcpu, msr),
 91		    "Quirk disabled, wanted '0' for MSR 0x%x, got 0x%lx",
 92		    msr, vcpu_get_msr(vcpu, msr));
 93	kvm_vm_free(vm);
 94}
 95
 96int main(int argc, char *argv[])
 97{
 98	const struct kvm_msr_list *feature_list;
 99	int i;
100
101	/*
102	 * Skip the entire test if MSR_FEATURES isn't supported, other tests
103	 * will cover the "regular" list of MSRs, the coverage here is purely
104	 * opportunistic and not interesting on its own.
105	 */
106	TEST_REQUIRE(kvm_has_cap(KVM_CAP_GET_MSR_FEATURES));
107
108	(void)kvm_get_msr_index_list();
109
110	feature_list = kvm_get_feature_msr_index_list();
111	for (i = 0; i < feature_list->nmsrs; i++)
112		test_feature_msr(feature_list->indices[i]);
113}