From 65b848b98f500a2e69922c4099224d3a6693e51e Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 2 Mar 2020 15:56:52 -0800 Subject: [PATCH] KVM: x86: Do host CPUID at load time to mask KVM cpu caps Mask kvm_cpu_caps based on host CPUID in preparation for overriding the CPUID results during KVM_GET_SUPPORTED_CPUID instead of doing the masking at runtime. Note, masking may or may not be necessary, e.g. the kernel rarely, if ever, sets real CPUID bits that are not supported by hardware. But, the code is cheap and only runs once at load, so an abundance of caution is warranted. No functional change intended. Reviewed-by: Vitaly Kuznetsov Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/cpuid.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index d4ada8f604a9a..80fccfd937bb5 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -263,8 +263,16 @@ out: static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask) { + const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32); + struct kvm_cpuid_entry2 entry; + reverse_cpuid_check(leaf); kvm_cpu_caps[leaf] &= mask; + + cpuid_count(cpuid.function, cpuid.index, + &entry.eax, &entry.ebx, &entry.ecx, &entry.edx); + + kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, &cpuid); } void kvm_set_cpu_caps(void) -- 2.39.5