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| author | Liran Alon <liran.alon@oracle.com> | 2018-03-23 03:01:32 +0300 |
|---|---|---|
| committer | Radim Krčmář <rkrcmar@redhat.com> | 2018-03-28 23:47:06 +0300 |
| commit | a042c26fd8e7c475636f967957e7130595478829 (patch) | |
| tree | b5da7443bf2caefe3bc5be76fd5cdcb1e113217f /arch/x86/kvm | |
| parent | 04140b4144cd888c080cddbb2be2ec603f00d081 (diff) | |
| download | linux-a042c26fd8e7c475636f967957e7130595478829.tar.xz | |
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: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@orcle.com>
[Used a comment from Sean J <sean.j.christopherson@intel.com>. - Radim]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/x86.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d15dc8cd6b9d..bb9dee4b4f58 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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) { |