From: Sean Christopherson Date: Thu, 28 Nov 2024 01:34:14 +0000 (-0800) Subject: KVM: x86: Update OS{XSAVE,PKE} bits in guest CPUID irrespective of host support X-Git-Tag: v6.14-rc1~94^2~4^2~21 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1f66590d7ff0bab04843fb89292e181c30d43e6c;p=thirdparty%2Fkernel%2Flinux.git KVM: x86: Update OS{XSAVE,PKE} bits in guest CPUID irrespective of host support 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 Reviewed-by: Binbin Wu Reviewed-by: Xiaoyao Li Link: https://lore.kernel.org/r/20241128013424.4096668-48-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index ced3c08a99c2e..d298b640ff74a 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -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));