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KVM: x86: Remove ordering check b/w MSR_PLATFORM_INFO and MISC_FEATURES_ENABLES

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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 <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-08-02 11:55:09 -07:00
parent a5d563890b
commit 1ded7a57b8
1 changed files with 1 additions and 3 deletions
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4
arch/x86/kvm/x86.c
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@@ -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;