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Re: [PATCH] pv32: Fix bogus cr2 on fault in emulation gate
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 21 May 2026 08:44:55 +0200
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- Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 21 May 2026 06:45:06 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 20.05.2026 18:27, Andrew Cooper wrote:
> On 20/05/2026 4:51 pm, Teddy Astie wrote:
>> __{put,get}_guest returns -EFAULT on access faults which causes
>> the injected cr2 to be off by 14 bytes (as EFAULT is 14) which is
>> incorrect.
>>
>> Fix the computation by relying on copy_{from,to}_guest_pv which
>> reports the number of remaining bytes instead of a negative errno,
>> such that we can compute the offset properly.
>>
>> Fixes: 70ad570b2799 ("x86/64: paravirt 32-on-64 call gate support")
>> Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
>
> Given it was __*_guest() before, I think we can use the
> __copy_*_guest_pv() variants.
>
> I can fix on commit if you're happy? Reviewed-by: Andrew Cooper
> <andrew.cooper3@xxxxxxxxxx>
>
> Jan, this wants committing ahead of your MISRA change, as it needs
> backporting.
It would be slightly easier in that order, but adjusting the backport
wouldn't be overly difficult if the Misra change went in first. Yet
that's still lacking an ack anyway.
Jan
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