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



> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx]
> Sent: Friday, November 22, 2019 6:16 AM
> 
> 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
> 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>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
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