linux-kernel - [PATCH 6/9] KVM: nVMX: Add consistency check for TSC

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Message-ID: <20250919005955.1366256-7-seanjc@google.com>
Date: Thu, 18 Sep 2025 17:59:52 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 6/9] KVM: nVMX: Add consistency check for TSC_MULTIPLIER=0

Add a missing consistency check on the TSC Multiplier being '0'.  Per the
SDM:

  If the "use TSC scaling" VM-execution control is 1, the TSC-multiplier
  must not be zero.

Fixes: d041b5ea9335 ("KVM: nVMX: Enable nested TSC scaling")
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/nested.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 5ac7ad207ef7..eb838ebeff0f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2906,6 +2906,10 @@ static int nested_check_vm_execution_controls(struct kvm_vcpu *vcpu,
 		}
 	}
 
+	if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_TSC_SCALING) &&
+	    CC(!vmcs12->tsc_multiplier))
+		return -EINVAL;
+
 	return 0;
 }
 
-- 
2.51.0.470.ga7dc726c21-goog