Messages in this thread Patch in this message | | | Subject | Re: [PATCH] KVM: nSVM: check for EFER.SVME=1 before entering guest | From | Krish Sadhukhan <> | Date | Wed, 18 Mar 2020 11:40:07 -0700 |
| |
On 3/18/20 5:41 AM, Paolo Bonzini wrote: > EFER is set for L2 using svm_set_efer, which hardcodes EFER_SVME to 1 and hides > an incorrect value for EFER.SVME in the L1 VMCB. Perform the check manually > to detect invalid guest state. > > Reported-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/kvm/svm.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 08568ae9f7a1..2125c6ae5951 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -3558,6 +3558,9 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm) > > static bool nested_vmcb_checks(struct vmcb *vmcb) > { > + if ((vmcb->save.efer & EFER_SVME) == 0) > + return false; > + > if ((vmcb->control.intercept & (1ULL << INTERCEPT_VMRUN)) == 0) > return false; >
Ah! This now tells me that I forgot the KVM fix that was supposed to accompany my patchset.
Do we need this check in software ? I wasn't checking the bit in KVM and instead I was just making sure that L0 sets that bit based on the setting in nested vmcb:
+static void nested_svm_set_efer(struct kvm_vcpu *vcpu, u64 nested_vmcb_efer) +{ + svm_set_efer(vcpu, nested_vmcb_efer); + + if (!(nested_vmcb_efer & EFER_SVME)) + to_svm(vcpu)->vmcb->save.efer &= ~EFER_SVME; +} + static int is_external_interrupt(u32 info) { info &= SVM_EVTINJ_TYPE_MASK | SVM_EVTINJ_VALID; @@ -3554,7 +3562,7 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 svm->vmcb->save.gdtr = nested_vmcb->save.gdtr; svm->vmcb->save.idtr = nested_vmcb->save.idtr; kvm_set_rflags(&svm->vcpu, nested_vmcb->save.rflags); - svm_set_efer(&svm->vcpu, nested_vmcb->save.efer); + nested_svm_set_efer(&svm->vcpu, nested_vmcb->save.efer); svm_set_cr0(&svm->vcpu, nested_vmcb->save.cr0); svm_set_cr4(&svm->vcpu, nested_vmcb->save.cr4); if (npt_enabled) {
| |