linux-kernel - [PATCH v2 0/2] KVM: SVM: Handle EferLmsleUnsupported

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Message-ID: <20251001001529.1119031-1-jmattson@google.com>
Date: Tue, 30 Sep 2025 17:14:06 -0700
From: Jim Mattson <jmattson@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Tom Lendacky <thomas.lendacky@....com>, 
	Jim Mattson <jmattson@...gle.com>, Perry Yuan <perry.yuan@....com>, 
	Sohil Mehta <sohil.mehta@...el.com>, "Xin Li (Intel)" <xin@...or.com>, 
	Joerg Roedel <joerg.roedel@....com>, Avi Kivity <avi@...hat.com>, linux-kernel@...r.kernel.org, 
	kvm@...r.kernel.org, Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [PATCH v2 0/2] KVM: SVM: Handle EferLmsleUnsupported

It is no longer the case that EFER.LMSLE is supported by all SVM-capable
processors. AMD enumerates the absence of this feature by CPUID
Fn8000_0008_EBX[EferLmlseUnsupported](bit 20)=1.

Advertise this defeature bit to userspace via KVM_GET_SUPPORTED_CPUID,
and don't allow a guest to set EFER.LMSLE on hardware that doesn't
support the feature.

Jim Mattson (2):
  KVM: x86: Advertise EferLmsleUnsupported to userspace
  KVM: SVM: Disallow EFER.LMSLE when not supported by hardware

 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kvm/cpuid.c               | 1 +
 arch/x86/kvm/svm/svm.c             | 4 +++-
 3 files changed, 5 insertions(+), 1 deletion(-)

-- 
2.51.0.618.g983fd99d29-goog