From eecf3985459a4f9128939fbbef75972d7468e4a1 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 9 Oct 2024 10:50:02 -0700 Subject: [PATCH] KVM: x86: Use '0' for guest RIP if PMI encounters protected guest state Explicitly return '0' for guest RIP when handling a PMI VM-Exit for a vCPU with protected guest state, i.e. when KVM can't read the real RIP. While there is no "right" value, and profiling a protect guest is rather futile, returning the last known RIP is worse than returning obviously "bad" data. E.g. for SEV-ES+, the last known RIP will often point somewhere in the guest's boot flow. Opportunistically add WARNs to effectively assert that the in_kernel() and get_ip() callbacks are restricted to the common PMI handler, as the return values for the protected guest state case are largely arbitrary, i.e. only make any sense whatsoever for PMIs, where the returned values have no functional impact and thus don't truly matter. Reviewed-by: Maxim Levitsky Link: https://lore.kernel.org/r/20241009175002.1118178-5-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index eeac4296d32a..dd28cae91796 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -13214,6 +13214,8 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu) { + WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)); + if (vcpu->arch.guest_state_protected) return true; @@ -13222,6 +13224,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu) unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu) { + WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)); + + if (vcpu->arch.guest_state_protected) + return 0; + return kvm_rip_read(vcpu); } -- 2.50.1