From: Sean Christopherson <seanjc@google.com>
Date: Fri, 19 Sep 2025 00:59:52 +0000 (-0700)
Subject: KVM: nVMX: Add consistency check for TSC_MULTIPLIER=0
X-Git-Tag: v6.19-rc1~103^2~5^2~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ae8e6ad84177456d8810a8ff3a5cf3f477fb0721;p=thirdparty%2Fkernel%2Flinux.git

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")
Link: https://lore.kernel.org/r/20250919005955.1366256-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
---

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index ffd2628b9c1ea..77b5f75cc2bb5 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2962,6 +2962,10 @@ 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;
 }