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Date:   Tue, 16 Mar 2021 12:15:48 +0000
To:     Ard Biesheuvel <ardb@kernel.org>
From:   Thomas Backlund <tmb@tmb.nu>
Cc:     "# 3.4.x" <stable@vger.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Eric Biggers <ebiggers@kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>
Reply-To: Thomas Backlund <tmb@tmb.nu>
Subject: Re: stable request
Message-ID: <1e6eb02b-e699-d1ff-9cfb-4ef77255e244@tmb.nu>
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References: <d5c825ba-cdcb-29eb-c434-83ef4db05ee0@tmb.nu> <CAMj1kXEM76Dejv1fTZ-1EmXpSsE-ZtKWf19dPNTSBRuPcAkreA@mail.gmail.com>
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Den 16.3.2021 kl. 12:17, skrev Ard Biesheuvel:
> On Tue, 16 Mar 2021 at 10:21, Thomas Backlund <tmb@tmb.nu> 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 t=
ree 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 a=
re Author of them I assume you know better about the facts :)


That's why I listed them as an extra "hopefully helfpful" info and datapoin=
t that they work...
We have been carrying them in 5.10 series since we rebased to 5.10.8 on Jan=
uary 17th, 2021


but in the end it's up to the -stable maintainers as you point out...

--
Thomas

> --
> Ard.
>
>
>> applied in this order:
>>
>>   From 032d049ea0f45b45c21f3f02b542aa18bc6b6428 Mon Sep 17 00:00:00 2001
>> From: Uros Bizjak <ubizjak@gmail.com>
>> Date: Fri, 27 Nov 2020 10:44:52 +0100
>> Subject: [PATCH] crypto: aesni - Use TEST %reg,%reg instead of CMP $0,%r=
eg
>>
>>   From ddf169a98f01d6fd46295ec0dd4c1d6385be65d4 Mon Sep 17 00:00:00 2001
>> From: Ard Biesheuvel <ardb@kernel.org>
>> Date: Tue, 8 Dec 2020 00:34:02 +0100
>> Subject: [PATCH] crypto: aesni - implement support for cts(cbc(aes))
>>
>>   From 86ad60a65f29dd862a11c22bb4b5be28d6c5cef1 Mon Sep 17 00:00:00 2001
>> From: Ard Biesheuvel <ardb@kernel.org>
>> Date: Thu, 31 Dec 2020 17:41:54 +0100
>> Subject: [PATCH] crypto: x86/aes-ni-xts - use direct calls to and 4-way
>> stride
>>
>>   From 2481104fe98d5b016fdd95d649b1235f21e491ba Mon Sep 17 00:00:00 2001
>> From: Ard Biesheuvel <ardb@kernel.org>
>> Date: Thu, 31 Dec 2020 17:41:55 +0100
>> Subject: [PATCH] crypto: x86/aes-ni-xts - rewrite and drop indirections
>> via glue helper
>>
>> --
>> Thomas
>>