From f91699d5692ddd0ee92b9487014fc477179ab3a7 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 18 Sep 2025 17:59:53 -0700 Subject: [PATCH] KVM: nVMX: Stuff vmcs02.TSC_MULTIPLIER early on for nested early checks If KVM is doing "early" nested VM-Enter consistency checks and TSC scaling is supported, stuff vmcs02's TSC Multiplier early on to avoid getting a false positive VM-Fail due to trying to do VM-Enter with TSC_MULTIPLIER=0. To minimize complexity around L1 vs. L2 TSC, KVM sets the actual TSC Multiplier rather late during VM-Entry, i.e. may have '0' at the time of early consistency checks. If vmcs12 has TSC Scaling enabled, use the multiplier from vmcs12 so that nested early checks actually check vmcs12 state, otherwise throw in an arbitrary value of '1' (anything non-zero is legal). Fixes: d041b5ea9335 ("KVM: nVMX: Enable nested TSC scaling") Link: https://lore.kernel.org/r/20250919005955.1366256-8-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/nested.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 77b5f75cc2bb5..efca276c67f09 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2371,6 +2371,13 @@ static void prepare_vmcs02_early_rare(struct vcpu_vmx *vmx, else vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid); } + + if (kvm_caps.has_tsc_control && nested_early_check) { + if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_TSC_SCALING)) + vmcs_write64(TSC_MULTIPLIER, vmcs12->tsc_multiplier); + else + vmcs_write64(TSC_MULTIPLIER, 1); + } } static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs01, -- 2.47.3