From fb7333dfd812062d3d51f377e70c1d3a3788472b Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Jun 2020 07:11:47 -0400 Subject: [PATCH] KVM: SVM: fix calls to is_intercept is_intercept takes an INTERCEPT_* constant, not SVM_EXIT_*; because of this, the compiler was removing the body of the conditionals, as if is_intercept returned 0. This unveils a latent bug: when clearing the VINTR intercept, int_ctl must also be changed in the L1 VMCB (svm->nested.hsave), just like the intercept itself is also changed in the L1 VMCB. Otherwise V_IRQ remains set and, due to the VINTR intercept being clear, we get a spurious injection of a vector 0 interrupt on the next L2->L1 vmexit. Reported-by: Qian Cai Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/nested.c | 2 +- arch/x86/kvm/svm/svm.c | 4 +++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 8a6db11dcb43..6bceafb19108 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -258,7 +258,7 @@ void sync_nested_vmcb_control(struct vcpu_svm *svm) /* Only a few fields of int_ctl are written by the processor. */ mask = V_IRQ_MASK | V_TPR_MASK; if (!(svm->nested.ctl.int_ctl & V_INTR_MASKING_MASK) && - is_intercept(svm, SVM_EXIT_VINTR)) { + is_intercept(svm, INTERCEPT_VINTR)) { /* * In order to request an interrupt window, L0 is usurping * svm->vmcb->control.int_ctl and possibly setting V_IRQ diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 9e333b91ff78..c8f5e87615d5 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1378,6 +1378,8 @@ static void svm_clear_vintr(struct vcpu_svm *svm) /* Drop int_ctl fields related to VINTR injection. */ svm->vmcb->control.int_ctl &= mask; if (is_guest_mode(&svm->vcpu)) { + svm->nested.hsave->control.int_ctl &= mask; + WARN_ON((svm->vmcb->control.int_ctl & V_TPR_MASK) != (svm->nested.ctl.int_ctl & V_TPR_MASK)); svm->vmcb->control.int_ctl |= svm->nested.ctl.int_ctl & ~mask; @@ -1999,7 +2001,7 @@ void svm_set_gif(struct vcpu_svm *svm, bool value) */ if (vgif_enabled(svm)) clr_intercept(svm, INTERCEPT_STGI); - if (is_intercept(svm, SVM_EXIT_VINTR)) + if (is_intercept(svm, INTERCEPT_VINTR)) svm_clear_vintr(svm); enable_gif(svm); -- 2.20.1