Re: [PATCH 4/7] x86/pv: Drop priv_op_ctxt.bpmatch and use pending_dbg instead

[Jinoh Kang <jinoh.kang.kr@xxxxxxxxx>]

On 9/16/23 05:36, Andrew Cooper wrote:
> @@ -658,7 +660,7 @@ static int cf_check rep_ins(
>  
>          ++*reps;
>  
> -        if ( poc->bpmatch || hypercall_preempt_check() )
> +        if ( poc->ctxt.retire.pending_dbg || hypercall_preempt_check() )
>              break;
>  
>          /* x86_emulate() clips the repetition count to ensure we don't wrap. 
> */

(snip)

> @@ -726,7 +729,7 @@ static int cf_check rep_outs(
>  
>          ++*reps;
>  
> -        if ( poc->bpmatch || hypercall_preempt_check() )
> +        if ( poc->ctxt.retire.pending_dbg || hypercall_preempt_check() )
>              break;
>  
>          /* x86_emulate() clips the repetition count to ensure we don't wrap. 
> */

These two hunks look like a behavioral change in singlestep mode.

This is actually a fix, assuming the emulator previously did not handle
'rep {in,out}s' in singlestep mode correctly, since it now checks for
PENDING_DBG.BS in addition to PENDING_DBG.B[0-4].

If this is the case, (at least) this part of the patch looks like a stable
candidate.  You might want to edit the commit message to reflect that.

(Ideally all the HWBP handling should be part of the emulator logic, but
 I don't see an easy way to generalize the PV-specific logic.  It could
 be its own patch anyway.)

-- 
Sincerely,
Jinoh Kang