This is a note to let you know that I've just added the patch titled
KVM: x86: Formalize blocking of nested pending exceptions
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-formalize-blocking-of-nested-pending-excepti.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3b49b279b88de56dc9d042feb7b8bf101a21ea30
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Tue Aug 30 23:16:02 2022 +0000
KVM: x86: Formalize blocking of nested pending exceptions
[ Upstream commit 72c14e00bdc445e96045c28d04bba45cbe69cf95 ]
Capture nested_run_pending as block_pending_exceptions so that the logic
of why exceptions are blocked only needs to be documented once instead of
at every place that employs the logic.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220830231614.3580124-16-seanjc@xxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Stable-dep-of: 7709aba8f716 ("KVM: x86: Morph pending exceptions to pending VM-Exits at queue time")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 8f991592d277..a6111392985c 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1356,10 +1356,22 @@ static inline bool nested_exit_on_init(struct vcpu_svm *svm)
static int svm_check_nested_events(struct kvm_vcpu *vcpu)
{
- struct vcpu_svm *svm = to_svm(vcpu);
- bool block_nested_events =
- kvm_event_needs_reinjection(vcpu) || svm->nested.nested_run_pending;
struct kvm_lapic *apic = vcpu->arch.apic;
+ struct vcpu_svm *svm = to_svm(vcpu);
+ /*
+ * Only a pending nested run blocks a pending exception. If there is a
+ * previously injected event, the pending exception occurred while said
+ * event was being delivered and thus needs to be handled.
+ */
+ bool block_nested_exceptions = svm->nested.nested_run_pending;
+ /*
+ * New events (not exceptions) are only recognized at instruction
+ * boundaries. If an event needs reinjection, then KVM is handling a
+ * VM-Exit that occurred _during_ instruction execution; new events are
+ * blocked until the instruction completes.
+ */
+ bool block_nested_events = block_nested_exceptions ||
+ kvm_event_needs_reinjection(vcpu);
if (lapic_in_kernel(vcpu) &&
test_bit(KVM_APIC_INIT, &apic->pending_events)) {
@@ -1372,13 +1384,7 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu)
}
if (vcpu->arch.exception.pending) {
- /*
- * Only a pending nested run can block a pending exception.
- * Otherwise an injected NMI/interrupt should either be
- * lost or delivered to the nested hypervisor in the EXITINTINFO
- * vmcb field, while delivering the pending exception.
- */
- if (svm->nested.nested_run_pending)
+ if (block_nested_exceptions)
return -EBUSY;
if (!nested_exit_on_exception(svm))
return 0;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 83239d47fc0f..7655b5acbbcd 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3904,11 +3904,23 @@ static bool nested_vmx_preemption_timer_pending(struct kvm_vcpu *vcpu)
static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
{
+ struct kvm_lapic *apic = vcpu->arch.apic;
struct vcpu_vmx *vmx = to_vmx(vcpu);
unsigned long exit_qual;
- bool block_nested_events =
- vmx->nested.nested_run_pending || kvm_event_needs_reinjection(vcpu);
- struct kvm_lapic *apic = vcpu->arch.apic;
+ /*
+ * Only a pending nested run blocks a pending exception. If there is a
+ * previously injected event, the pending exception occurred while said
+ * event was being delivered and thus needs to be handled.
+ */
+ bool block_nested_exceptions = vmx->nested.nested_run_pending;
+ /*
+ * New events (not exceptions) are only recognized at instruction
+ * boundaries. If an event needs reinjection, then KVM is handling a
+ * VM-Exit that occurred _during_ instruction execution; new events are
+ * blocked until the instruction completes.
+ */
+ bool block_nested_events = block_nested_exceptions ||
+ kvm_event_needs_reinjection(vcpu);
if (lapic_in_kernel(vcpu) &&
test_bit(KVM_APIC_INIT, &apic->pending_events)) {
@@ -3947,15 +3959,10 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
* for TSS T flag #DBs). KVM also doesn't save/restore pending MTF
* across SMI/RSM as it should; that needs to be addressed in order to
* prioritize SMI over MTF and trap-like #DBs.
- *
- * Note that only a pending nested run can block a pending exception.
- * Otherwise an injected NMI/interrupt should either be
- * lost or delivered to the nested hypervisor in the IDT_VECTORING_INFO,
- * while delivering the pending exception.
*/
if (vcpu->arch.exception.pending &&
!(vmx_get_pending_dbg_trap(vcpu) & ~DR6_BT)) {
- if (vmx->nested.nested_run_pending)
+ if (block_nested_exceptions)
return -EBUSY;
if (!nested_vmx_check_exception(vcpu, &exit_qual))
goto no_vmexit;
@@ -3972,7 +3979,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
}
if (vcpu->arch.exception.pending) {
- if (vmx->nested.nested_run_pending)
+ if (block_nested_exceptions)
return -EBUSY;
if (!nested_vmx_check_exception(vcpu, &exit_qual))
goto no_vmexit;
