From 1ded7a57b8050ea92c0ab0253b11a917ae1427ff Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 2 Aug 2024 11:55:09 -0700 Subject: [PATCH] KVM: x86: Remove ordering check b/w MSR_PLATFORM_INFO and MISC_FEATURES_ENABLES Drop KVM's odd restriction that disallows clearing CPUID_FAULT in MSR_PLATFORM_INFO if CPL>0 CPUID faulting is enabled in MSR_MISC_FEATURES_ENABLES. KVM generally doesn't require specific ordering when userspace sets MSRs, and the completely arbitrary order of MSRs in emulated_msrs_all means that a userspace that uses KVM's list verbatim could run afoul of the check. Dropping the restriction obviously means that userspace could stuff a nonsensical vCPU model, but that's the case all over KVM. KVM typically restricts userspace MSR writes only when it makes things easier for KVM and/or userspace. Link: https://lore.kernel.org/r/20240802185511.305849-8-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7e59d3a0801a2..366fd89d08944 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4116,9 +4116,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vcpu->arch.osvw.status = data; break; case MSR_PLATFORM_INFO: - if (!msr_info->host_initiated || - (!(data & MSR_PLATFORM_INFO_CPUID_FAULT) && - cpuid_fault_enabled(vcpu))) + if (!msr_info->host_initiated) return 1; vcpu->arch.msr_platform_info = data; break; -- 2.39.5