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KVM: x86: Update OS{XSAVE,PKE} bits in guest CPUID irrespective of host support

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When making runtime CPUID updates, change OSXSAVE and OSPKE even if their
respective base features (XSAVE, PKU) are not supported by the host.  KVM
already incorporates host support in the vCPU's effective reserved CR4 bits.
I.e. OSXSAVE and OSPKE can be set if and only if the host supports them.

And conversely, since KVM's ABI is that KVM owns the dynamic OS feature
flags, clearing them when they obviously aren't supported and thus can't
be enabled is arguably a fix.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20241128013424.4096668-48-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-11-27 17:34:14 -08:00
parent cfd1574526
commit 1f66590d7f
1 changed files with 3 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/kvm/cpuid.c
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@@ -297,10 +297,8 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
best = kvm_find_cpuid_entry(vcpu, 1);
if (best) {
/* Update OSXSAVE bit */
if (boot_cpu_has(X86_FEATURE_XSAVE))
cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE));
cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE));
cpuid_entry_change(best, X86_FEATURE_APIC,
vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
@@ -312,7 +310,7 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
}
best = kvm_find_cpuid_entry_index(vcpu, 7, 0);
if (best && boot_cpu_has(X86_FEATURE_PKU))
if (best)
cpuid_entry_change(best, X86_FEATURE_OSPKE,
kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE));