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Commit a042c26f authored by Liran Alon's avatar Liran Alon Committed by Radim Krčmář
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KVM: x86: Fix misleading comments on handling pending exceptions 



The reason that exception.pending should block re-injection of
NMI/interrupt is not described correctly in comment in code.
Instead, it describes why a pending exception should be injected
before a pending NMI/interrupt.

Therefore, move currently present comment to code-block evaluating
a new pending event which explains why exception.pending is evaluated
first.
In addition, create a new comment describing that exception.pending
blocks re-injection of NMI/interrupt because the exception was
queued by handling vmexit which was due to NMI/interrupt delivery.

Signed-off-by: default avatarLiran Alon <liran.alon@oracle.com>
Reviewed-by: default avatarNikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: default avatarKrish Sadhukhan <krish.sadhukhan@orcle.com>
[Used a comment from Sean J <sean.j.christopherson@intel.com>. - Radim]
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent 04140b41

arch/x86/kvm/x86.c

+12 −2
Original line number Diff line number Diff line
@@ -6758,8 +6758,18 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool req_int_win) 
	}



	/*

	 * Exceptions must be injected immediately, or the exception

	 * frame will have the address of the NMI or interrupt handler.

	 * Do not inject an NMI or interrupt if there is a pending

	 * exception.  Exceptions and interrupts are recognized at

	 * instruction boundaries, i.e. the start of an instruction.

	 * Trap-like exceptions, e.g. #DB, have higher priority than

	 * NMIs and interrupts, i.e. traps are recognized before an

	 * NMI/interrupt that's pending on the same instruction.

	 * Fault-like exceptions, e.g. #GP and #PF, are the lowest

	 * priority, but are only generated (pended) during instruction

	 * execution, i.e. a pending fault-like exception means the

	 * fault occurred on the *previous* instruction and must be

	 * serviced prior to recognizing any new events in order to

	 * fully complete the previous instruction.

	 */

	if (!vcpu->arch.exception.pending) {

		if (vcpu->arch.nmi_injected) {