On Sun, Nov 15, 2009 at 02:41:58PM +0200, Avi Kivity wrote:
> On 11/12/2009 02:26 PM, Gleb Natapov wrote:
> >>
> >>- if (vcpu->arch.exception.pending) {
> >>- switch(vcpu->arch.exception.nr) {
> >>- case DF_VECTOR:
> >>- /* triple fault -> shutdown */
> >>- set_bit(KVM_REQ_TRIPLE_FAULT,&vcpu->requests);
> >>- return;
> >>- case PF_VECTOR:
> >>- vcpu->arch.exception.nr = DF_VECTOR;
> >>- vcpu->arch.exception.error_code = 0;
> >>- return;
> >>- default:
> >>- /* replace previous exception with a new one in a hope
> >>- that instruction re-execution will regenerate lost
> >>- exception */
> >>- vcpu->arch.exception.pending = false;
> >>- break;
> >When exceptions are handled serially previous exception have to be
> >replaced by new one. Think about #PF during #DE. #PF should be handled first
> >before #DE can proceed.
>
> "replacing" exceptions is dangerous in the case of debug exceptions
> and machine checks, since restarting execution won't recover them.
>
But not replacing them is not better. No point in re-injecting
exception that causes another exception.
--
Gleb.
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