Re: [Xen-devel] [PATCH 1/2] x86/vtx: Fix fault semantics for early task switch failures

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Nov 21, 2019 at 10:15:50PM +0000, Andrew Cooper wrote:
> The VT-x task switch handler adds inst_len to rip before calling
> hvm_task_switch().  This causes early faults to be delivered to the guest with

By early faults you mean faults injected by hvm_task_switch itself for
example?

> trap semantics, and break restartibility.
> 
> Instead, pass the instruction length into hvm_task_switch() and write it into
> the outgoing tss only, leaving rip in its original location.
> 
> For now, pass 0 on the SVM side.  This highlights a separate preexisting bug
> which will be addressed in the following patch.
> 
> While adjusting call sites, drop the unnecessary uint16_t cast.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Code LGTM:

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks, Roger.

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