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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Oliver Upton <oupton@google.com>, Peter Shier <pshier@google.com>
Subject: [PATCH 14/21] KVM: x86: Formalize blocking of nested pending exceptions
Date: Fri, 11 Mar 2022 03:27:54 +0000	[thread overview]
Message-ID: <20220311032801.3467418-15-seanjc@google.com> (raw)
In-Reply-To: <20220311032801.3467418-1-seanjc@google.com>

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>
---
 arch/x86/kvm/svm/nested.c | 20 ++++++++++----------
 arch/x86/kvm/vmx/nested.c | 23 ++++++++++++-----------
 2 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index bef5a93166a8..60df9d4d19b5 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1201,10 +1201,16 @@ 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;
+	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)) {
@@ -1217,13 +1223,7 @@ 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 c88031d44148..01cf579c0260 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3878,11 +3878,17 @@ 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;
+	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)) {
@@ -3916,15 +3922,10 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
 	 * Process exceptions that are higher priority than Monitor Trap Flag:
 	 * fault-like exceptions, TSS T flag #DB (not emulated by KVM, but
 	 * could theoretically come in from userspace), and ICEBP (INT1).
-	 *
-	 * 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;
@@ -3941,7 +3942,7 @@ 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;
-- 
2.35.1.723.g4982287a31-goog


  parent reply	other threads:[~2022-03-11  3:29 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-11  3:27 [PATCH 00/21] KVM: x86: Event/exception fixes and cleanups Sean Christopherson
2022-03-11  3:27 ` [PATCH 01/21] KVM: x86: Return immediately from x86_emulate_instruction() on code #DB Sean Christopherson
2022-03-11  3:27 ` [PATCH 02/21] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit" Sean Christopherson
2022-03-11  3:27 ` [PATCH 03/21] KVM: VMX: Drop bits 31:16 when shoving exception error code into VMCS Sean Christopherson
2022-03-11  3:27 ` [PATCH 04/21] KVM: x86: Don't check for code breakpoints when emulating on exception Sean Christopherson
2022-03-11  3:27 ` [PATCH 05/21] KVM: nVMX: Treat General Detect #DB (DR7.GD=1) as fault-like Sean Christopherson
2022-03-11  3:27 ` [PATCH 06/21] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag Sean Christopherson
2022-03-11  3:27 ` [PATCH 07/21] KVM: x86: Treat #DBs from the emulator as fault-like (code and DR7.GD=1) Sean Christopherson
2022-03-11  3:27 ` [PATCH 08/21] KVM: x86: Use DR7_GD macro instead of open coding check in emulator Sean Christopherson
2022-03-11  3:27 ` [PATCH 09/21] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS Sean Christopherson
2022-03-11  3:27 ` [PATCH 10/21] KVM: nVMX: Unconditionally clear mtf_pending on nested VM-Exit Sean Christopherson
2022-03-11  3:27 ` [PATCH 11/21] KVM: VMX: Inject #PF on ENCLS as "emulated" #PF Sean Christopherson
2022-03-11  3:27 ` [PATCH 12/21] KVM: x86: Rename kvm_x86_ops.queue_exception to inject_exception Sean Christopherson
2022-03-11  3:27 ` [PATCH 13/21] KVM: x86: Make kvm_queued_exception a properly named, visible struct Sean Christopherson
2022-03-11  3:27 ` Sean Christopherson [this message]
2022-03-11  3:27 ` [PATCH 15/21] KVM: x86: Use kvm_queue_exception_e() to queue #DF Sean Christopherson
2022-03-11  3:27 ` [PATCH 16/21] KVM: x86: Hoist nested event checks above event injection logic Sean Christopherson
2022-03-11  3:27 ` [PATCH 17/21] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit Sean Christopherson
2022-03-11  3:27 ` [PATCH 18/21] KVM: x86: Morph pending exceptions to pending VM-Exits at queue time Sean Christopherson
2022-03-11  3:27 ` [PATCH 19/21] KVM: VMX: Update MTF and ICEBP comments to document KVM's subtle behavior Sean Christopherson
2022-03-11  3:28 ` [PATCH 20/21] KVM: selftests: Use uapi header to get VMX and SVM exit reasons/codes Sean Christopherson
2022-03-11  3:28 ` [PATCH 21/21] KVM: selftests: Add an x86-only test to verify nested exception queueing Sean Christopherson
2022-03-11 16:30 ` [PATCH 00/21] KVM: x86: Event/exception fixes and cleanups Maciej S. Szmigiero
2022-03-13  9:22 ` Maxim Levitsky
2022-03-24 21:31   ` Sean Christopherson
2022-03-25 21:25     ` Maciej S. Szmigiero
2022-03-25 23:02       ` Sean Christopherson
2022-03-26  0:21         ` Maciej S. Szmigiero
2022-03-27 15:06     ` Maxim Levitsky
2022-03-28 17:50       ` Sean Christopherson
2022-03-29 10:45         ` Maxim Levitsky
2022-03-29 15:43           ` Sean Christopherson

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