On 27.02.19 17:02, Richard Henderson wrote:
> On 2/26/19 3:38 AM, David Hildenbrand wrote:
>> Also fairly easy to implement. One issue we have is that exceptions will
>> result in some vectors already being modified. At least handle it
>> consistently per vector by using a temporary vector. Good enough for
>> now, add a FIXME.
>>
>> Signed-off-by: David Hildenbrand <da...@redhat.com>
>> ---
>> target/s390x/insn-data.def | 2 ++
>> target/s390x/translate_vx.inc.c | 26 ++++++++++++++++++++++++++
>> 2 files changed, 28 insertions(+)
>
> I suppose the fixme is good enough. For the record, I think you could do the
> check with just two loads -- the first and last quadword. After that, none of
> the other loads can fault, and you can store everything else into the
> destination vectors as you read them.
Aren't such approaches prone to races if other VCPUs invalidate page
tables/TLB entries?
(or am I messing up things and the MMU of this VCPU won't be touched
while in this block and once we touched all applicable pages, it cannot
fail anymore?)
>
> Also missing for the fixme: MO_ALIGN{,_16}.
Just like the other occurrence, I think MO_ALIGN would be wrong.
"Setting the alignment hint to a non-zero value
that doesn’t correspond to the alignment of the
second operand may reduce performance on
some models."
>
> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
>
Thanks!
>
> r~
>
--
Thanks,
David / dhildenb
