From 8cd0e1c75c2556e1ee7add9a2d459502bc7c27e1 Mon Sep 17 00:00:00 2001 From: Ravi Bangoria Date: Thu, 8 Aug 2024 06:29:36 +0000 Subject: [PATCH] KVM: SVM: Don't advertise Bus Lock Detect to guest if SVM support is missing BugLink: https://bugs.launchpad.net/bugs/2085849 commit 54950bfe2b69cdc06ef753872b5225e54eb73506 upstream. If host supports Bus Lock Detect, KVM advertises it to guests even if SVM support is absent. Additionally, guest wouldn't be able to use it despite guest CPUID bit being set. Fix it by unconditionally clearing the feature bit in KVM cpu capability. Reported-by: Jim Mattson Closes: https://lore.kernel.org/r/CALMp9eRet6+v8Y1Q-i6mqPm4hUow_kJNhmVHfOV8tMfuSS=tVg@mail.gmail.com Fixes: 76ea438b4afc ("KVM: X86: Expose bus lock debug exception to guest") Cc: stable@vger.kernel.org Signed-off-by: Ravi Bangoria Reviewed-by: Jim Mattson Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20240808062937.1149-4-ravi.bangoria@amd.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman Signed-off-by: Manuel Diewald Signed-off-by: Roxana Nicolescu --- arch/x86/kvm/svm/svm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 08edb49f7270..9d070f7da796 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -5176,6 +5176,9 @@ static __init void svm_set_cpu_caps(void) /* CPUID 0x8000001F (SME/SEV features) */ sev_set_cpu_caps(); + + /* Don't advertise Bus Lock Detect to guest if SVM support is absent */ + kvm_cpu_cap_clear(X86_FEATURE_BUS_LOCK_DETECT); } static __init int svm_hardware_setup(void)