From a0860d68a25dee4e51e7d3e067a66ca765776fe8 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 13 Dec 2022 06:23:04 +0000 Subject: [PATCH] KVM: nVMX: Don't stuff secondary execution control if it's not supported When stuffing the allowed secondary execution controls for nested VMX in response to CPUID updates, don't set the allowed-1 bit for a feature that isn't supported by KVM, i.e. isn't allowed by the canonical vmcs_config. WARN if KVM attempts to manipulate a feature that isn't supported. All features that are currently stuffed are always advertised to L1 for nested VMX if they are supported in KVM's base configuration, and no additional features should ever be added to the CPUID-induced stuffing (updating VMX MSRs in response to CPUID updates is a long-standing KVM flaw that is slowly being fixed). Signed-off-by: Sean Christopherson Message-Id: <20221213062306.667649-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmx.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index fe5615fd8295c4..fc9008dbed3348 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4459,6 +4459,13 @@ vmx_adjust_secondary_exec_control(struct vcpu_vmx *vmx, u32 *exec_control, * controls for features that are/aren't exposed to the guest. */ if (nested) { + /* + * All features that can be added or removed to VMX MSRs must + * be supported in the first place for nested virtualization. + */ + if (WARN_ON_ONCE(!(vmcs_config.nested.secondary_ctls_high & control))) + enabled = false; + if (enabled) vmx->nested.msrs.secondary_ctls_high |= control; else