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Subject[PATCH v2 13/24] KVM: x86: Formalize blocking of nested pending exceptions
From
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@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/svm/nested.c | 26 ++++++++++++++++----------
arch/x86/kvm/vmx/nested.c | 29 ++++++++++++++++++-----------
2 files changed, 34 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index f4cc12ee21d1..f5676c2679d0 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1352,10 +1352,22 @@ 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)) {
@@ -1368,13 +1380,7 @@ 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 42eccdcc2a4b..a0a4eddce445 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3892,11 +3892,23 @@ static bool nested_vmx_preemption_timer_pending(struct kvm_vcpu *vcpu)

static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
{
- 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;
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ unsigned long exit_qual;
+ /*
+ * 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)) {
@@ -3935,15 +3947,10 @@ 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;
@@ -3960,7 +3967,7 @@ 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;
--
2.37.0.170.g444d1eabd0-goog
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