From: Jim Mattson Date: Wed, 27 May 2026 17:43:44 +0000 (-0700) Subject: KVM: x86: Prioritize CPUID faulting over CPUID VM-exits in nested VMX X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=be7fd7c3e8bcfd3a1804567ce5cf9ca3b254c1ba;p=thirdparty%2Fkernel%2Flinux.git KVM: x86: Prioritize CPUID faulting over CPUID VM-exits in nested VMX Per the Intel SDM, "Certain exceptions have priority over VM exits. These include invalid-opcode exceptions, faults based on privilege level, and general-protection exceptions that are based on checking I/O permission bits in the task-state segment (TSS)." Ensure that when L2 executes CPUID at CPL > 0 while L1 has enabled CPUID faulting, KVM intercepts the exit in L0 and queues #GP rather than forwarding the CPUID VM-exit to L1. Empirical testing confirms that this #GP has higher precedence than a CPUID VM-exit on Granite Rapids (F/M/S 6/0xad/1). Fixes: db2336a80489 ("KVM: x86: virtualize cpuid faulting") Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260513224608.1859737-1-jmattson%40google.com?part=3 Signed-off-by: Jim Mattson Link: https://patch.msgid.link/20260527174347.2356165-3-jmattson@google.com Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index a78ce0080963..30dcabc899a2 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -6552,6 +6552,8 @@ static bool nested_vmx_l0_wants_exit(struct kvm_vcpu *vcpu, nested_evmcs_l2_tlb_flush_enabled(vcpu) && kvm_hv_is_tlb_flush_hcall(vcpu); #endif + case EXIT_REASON_CPUID: + return !kvm_is_cpuid_allowed(vcpu); default: break; }