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 ffd2628b9c1eab45751fd54ed82f6ea1a45e0aa6..77b5f75cc2bb5f7afc334e4c2f8f87072f72f0b8 100644 (file)
--- 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;
 }