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 <cai@xxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
Vitaly, can you give this a shot with Hyper-V? I have already
placed it on kvm/queue, it passes both svm.flat and KVM-on-KVM
smoke tests.
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);
--
2.26.2
