On Tue, Mar 16, 2021 at 01:35:40PM +0100, Ard Biesheuvel wrote:
On Tue, 16 Mar 2021 at 13:28, Thomas Backlund <tmb@xxxxxx> wrote:
Den 16.3.2021 kl. 14:15, skrev Thomas Backlund:
>
> Den 16.3.2021 kl. 12:17, skrev Ard Biesheuvel:
>> On Tue, 16 Mar 2021 at 10:21, Thomas Backlund <tmb@xxxxxx> wrote:
>>> Den 16.3.2021 kl. 08:37, skrev Ard Biesheuvel:
>>>> Please consider backporting commit
>>>>
>>>> 86ad60a65f29dd862a11c22bb4b5be28d6c5cef1
>>>> crypto: x86/aes-ni-xts - use direct calls to and 4-way stride
>>>>
>>>> to stable. It addresses a rather substantial retpoline-related
>>>> performance regression in the AES-NI XTS code, which is a widely used
>>>> disk encryption algorithm on x86.
>>>>
>>> To get all the nice bits, we added the following in Mageia 5.10 / 5.11
>>> series kerenels (the 2 first is needed to get the third to apply/build
>>> nicely):
>>>
>> I will leave it up to the -stable maintainers to decide, but I will
>> point out that none of the additional patches fix any bugs, so this
>> may violate the stable kernel rules. In fact, I deliberately split the
>> XTS changes into two patches so that the first one could be
>> backported individually.
>
> Yes, I understand that.
>
> but commit
>
> 86ad60a65f29dd862a11c22bb4b5be28d6c5cef1
> crypto: x86/aes-ni-xts - use direct calls to and 4-way stride
>
> only applies cleanly on 5.11.
>
>
> So if it's wanted in 5.10 you need the 2 others too... unless you intend to provide a tested backport...
> and IIRC GregKH prefers 1:1 matching of patches between -stable and linus tree unless they are too intrusive.
>
>
> As for the last one I seem to remember comments that it too was part of the "affects performance", but I might be remembering wrong... and since you are Author of them I assume you know better about the facts :)
>
>
> That's why I listed them as an extra "hopefully helfpful" info and datapoint that they work...
> We have been carrying them in 5.10 series since we rebased to 5.10.8 on January 17th, 2021
>
>
> but in the end it's up to the -stable maintainers as you point out...
and now I re-checked...
Only the first is needed to get your fix to apply cleanly on 5.10
the second came in as a pre-req for the fourth patch...
OK so that would be
032d049ea0f45b45c21f3f02b542aa18bc6b6428
Uros Bizjak <ubizjak@xxxxxxxxx>
crypto: aesni - Use TEST %reg,%reg instead of CMP $0,%reg
which is already in 5.11, but needs to be backported as well for the
originally requested backport to apply cleanly to 5.10 and earlier.
Thanks for digging that up.
Queued up for 5.10 and 5.11.
What about anything older than 5.10? Looks like it's needed there too?
--
Thanks,
Sasha
