From bc2ca3680b30869ee9a764ab72c143070f1afec8 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 2 Aug 2024 11:55:04 -0700 Subject: [PATCH] KVM: x86: Disallow changing MSR_PLATFORM_INFO after vCPU has run Tag MSR_PLATFORM_INFO as a feature MSR (because it is), i.e. disallow it from being modified after the vCPU has run. To make KVM's selftest compliant, simply delete the userspace MSR write that restores KVM's original value at the end of the test. Verifying that userspace can write back what it originally read is uninteresting in this particular case, because KVM doesn't enforce _any_ bits in the MSR, i.e. userspace should be able to write any arbitrary value. Link: https://lore.kernel.org/r/20240802185511.305849-3-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 1 + tools/testing/selftests/kvm/x86_64/platform_info_test.c | 2 -- 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3787e6a717439..16804637ba97b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -451,6 +451,7 @@ static const u32 msr_based_features_all_except_vmx[] = { MSR_IA32_UCODE_REV, MSR_IA32_ARCH_CAPABILITIES, MSR_IA32_PERF_CAPABILITIES, + MSR_PLATFORM_INFO, }; static u32 msr_based_features[ARRAY_SIZE(msr_based_features_all_except_vmx) + diff --git a/tools/testing/selftests/kvm/x86_64/platform_info_test.c b/tools/testing/selftests/kvm/x86_64/platform_info_test.c index eda88080c1868..9cbf283ebc55f 100644 --- a/tools/testing/selftests/kvm/x86_64/platform_info_test.c +++ b/tools/testing/selftests/kvm/x86_64/platform_info_test.c @@ -72,8 +72,6 @@ int main(int argc, char *argv[]) } done: - vcpu_set_msr(vcpu, MSR_PLATFORM_INFO, msr_platform_info); - kvm_vm_free(vm); return 0; -- 2.50.1