From: Sean Christopherson Date: Tue, 13 Jul 2021 16:32:43 +0000 (-0700) Subject: KVM: SVM: Require exact CPUID.0x1 match when stuffing EDX at INIT X-Git-Tag: v5.15-rc1~65^2~122 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=067a456d091d05fdae32cae350410d905968b645;p=thirdparty%2Fkernel%2Flinux.git KVM: SVM: Require exact CPUID.0x1 match when stuffing EDX at INIT Do not allow an inexact CPUID "match" when querying the guest's CPUID.0x1 to stuff EDX during INIT. In the common case, where the guest CPU model is an AMD variant, allowing an inexact match is a nop since KVM doesn't emulate Intel's goofy "out-of-range" logic for AMD and Hygon. If the vCPU model happens to be an Intel variant, an inexact match is possible if and only if the max CPUID leaf is precisely '0'. Aside from the fact that there's probably no CPU in existence with a single CPUID leaf, if the max CPUID leaf is '0', that means that CPUID.0.EAX is '0', and thus an inexact match for CPUID.0x1.EAX will also yield '0'. So, with lots of twisty logic, no functional change intended. Reviewed-by: Reiji Watanabe Signed-off-by: Sean Christopherson Message-Id: <20210713163324.627647-6-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 7845232b6fb68..f4b6fec6252f2 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1346,7 +1346,7 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) } init_vmcb(vcpu); - kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy, false); + kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy, true); kvm_rdx_write(vcpu, eax); if (kvm_vcpu_apicv_active(vcpu) && !init_event)