[PATCH 5/5] KVM: svm: Set X86_FEATURE_NO_LMSLE when !nested

From: Jim Mattson <jmattson@google.com>
To: Avi Kivity <avi@redhat.com>, Babu Moger <babu.moger@amd.com>,
	Borislav Petkov <bp@alien8.de>,
	"Chang S. Bae" <chang.seok.bae@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Joerg Roedel <joerg.roedel@amd.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Sean Christopherson <seanjc@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Wyes Karny <wyes.karny@amd.com>,
	x86@kernel.org
Cc: Jim Mattson <jmattson@google.com>
Subject: [PATCH 5/5] KVM: svm: Set X86_FEATURE_NO_LMSLE when !nested
Date: Thu, 15 Sep 2022 21:58:32 -0700	[thread overview]
Message-ID: <20220916045832.461395-6-jmattson@google.com> (raw)
In-Reply-To: <20220916045832.461395-1-jmattson@google.com>

KVM has never allowed a guest to set EFER.LMSLE when the "nested"
module parameter was false. In the past, there was no way for a guest
to know whether or not this was a legal EFER bit. Now, we can let the
guest know this bit is illegal by reporting X86_FEATURE_NO_LMSLE in
KVM_GET_SUPPORTED_CPUID.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/svm/svm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7c4fd594166c..942602d503ad 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4945,6 +4945,8 @@ static __init void svm_set_cpu_caps(void)
 	if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
 	    boot_cpu_has(X86_FEATURE_AMD_SSBD))
 		kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
+	if (!nested)
+		kvm_cpu_cap_set(X86_FEATURE_NO_LMSLE);
 
 	/* AMD PMU PERFCTR_CORE CPUID */
 	if (enable_pmu && boot_cpu_has(X86_FEATURE_PERFCTR_CORE))
-- 
2.37.3.968.ga6b4b080e4-goog

