Re: [Xen-devel] [PATCH] x86/HVM: correctly deal with benign exceptions when combining two

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.04.19 at 15:39, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 11/04/2019 08:31, Jan Beulich wrote:
>> Would you mind helping me make the connection between #AC
>> delivery (and its emulation) and XSA-170, being about VM entry
>> with non-canonical %rip?
> 
> Ah - that wasn't the connection I was trying to make.
> 
> Because our emulation of event delivery is currently specific to SVM,
> and doesn't perform alignment checking, Xen will never end up in a case
> were #AC will be delivered second.
> 
> If you recall, the injection support used to be common, then moved to
> being SVM specific.  If it were to move back to being common, we could
> fix XSA-170 while maintaining architecturally correct behaviour, by
> fully emulating the event injection, which would bypass the incorrect
> VMEntry consistency check which causes XSA-170 in the first place.

Oh, I see - you mean because by emulating the injection we'd
avoid the hardware ever seeing the non-canonical %rip.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel