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From: Oliver Upton <oupton@google.com>
To: kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Jim Mattson <jmattson@google.com>,
	Peter Shier <pshier@google.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Oliver Upton <oupton@google.com>
Subject: [PATCH v2 3/5] KVM: x86: Deliver exception payload on KVM_GET_VCPU_EVENTS
Date: Tue, 28 Jan 2020 01:27:13 -0800	[thread overview]
Message-ID: <20200128092715.69429-4-oupton@google.com> (raw)
In-Reply-To: <20200128092715.69429-1-oupton@google.com>

KVM doesn't utilize exception payloads by default, as this behavior
diverges from the expectations of the userspace API. However, this
constraint only applies if KVM is servicing a KVM_GET_VCPU_EVENTS ioctl
before delivering the exception.

Use exception payloads unconditionally if the vcpu is in guest mode.
Deliver the exception payload before completing a KVM_GET_VCPU_EVENTS
to ensure API compatibility.

Signed-off-by: Oliver Upton <oupton@google.com>
---
 arch/x86/kvm/x86.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7a341c0c978a..9f080101618c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -497,19 +497,7 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
 		vcpu->arch.exception.error_code = error_code;
 		vcpu->arch.exception.has_payload = has_payload;
 		vcpu->arch.exception.payload = payload;
-		/*
-		 * In guest mode, payload delivery should be deferred,
-		 * so that the L1 hypervisor can intercept #PF before
-		 * CR2 is modified (or intercept #DB before DR6 is
-		 * modified under nVMX).  However, for ABI
-		 * compatibility with KVM_GET_VCPU_EVENTS and
-		 * KVM_SET_VCPU_EVENTS, we can't delay payload
-		 * delivery unless userspace has enabled this
-		 * functionality via the per-VM capability,
-		 * KVM_CAP_EXCEPTION_PAYLOAD.
-		 */
-		if (!vcpu->kvm->arch.exception_payload_enabled ||
-		    !is_guest_mode(vcpu))
+		if (!is_guest_mode(vcpu))
 			kvm_deliver_exception_payload(vcpu);
 		return;
 	}
@@ -3790,6 +3778,21 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 {
 	process_nmi(vcpu);
 
+	/*
+	 * In guest mode, payload delivery should be deferred,
+	 * so that the L1 hypervisor can intercept #PF before
+	 * CR2 is modified (or intercept #DB before DR6 is
+	 * modified under nVMX).  However, for ABI
+	 * compatibility with KVM_GET_VCPU_EVENTS and
+	 * KVM_SET_VCPU_EVENTS, we can't delay payload
+	 * delivery unless userspace has enabled this
+	 * functionality via the per-VM capability,
+	 * KVM_CAP_EXCEPTION_PAYLOAD.
+	 */
+	if (!vcpu->kvm->arch.exception_payload_enabled &&
+	    vcpu->arch.exception.pending && vcpu->arch.exception.has_payload)
+		kvm_deliver_exception_payload(vcpu);
+
 	/*
 	 * The API doesn't provide the instruction length for software
 	 * exceptions, so don't report them. As long as the guest RIP
-- 
2.25.0.341.g760bfbb309-goog


  parent reply	other threads:[~2020-01-28  9:27 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-28  9:27 [PATCH v2 0/5] Handle monitor trap flag during instruction emulation Oliver Upton
2020-01-28  9:27 ` [PATCH v2 1/5] KVM: x86: Mask off reserved bit from #DB exception payload Oliver Upton
2020-01-28  9:27 ` [PATCH v2 2/5] KVM: nVMX: Handle pending #DB when injecting INIT VM-exit Oliver Upton
2020-02-03 19:13   ` Sean Christopherson
2020-02-03 23:00     ` Sean Christopherson
2020-01-28  9:27 ` Oliver Upton [this message]
2020-02-03 19:48   ` [PATCH v2 3/5] KVM: x86: Deliver exception payload on KVM_GET_VCPU_EVENTS Sean Christopherson
2020-01-28  9:27 ` [PATCH v2 4/5] KVM: nVMX: Emulate MTF when performing instruction emulation Oliver Upton
2020-02-03 22:58   ` Sean Christopherson
2020-02-06 10:42     ` Oliver Upton
2021-08-13  0:23   ` Jim Mattson
2021-08-13 16:35     ` Sean Christopherson
2021-08-13 17:03       ` Jim Mattson
2020-01-28  9:27 ` [kvm-unit-tests PATCH v2 5/5] x86: VMX: Add tests for monitor trap flag Oliver Upton
2020-01-28  9:39 ` [PATCH v2 0/5] Handle monitor trap flag during instruction emulation Oliver Upton

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