Re: [Qemu-devel] regression: target/ppc: convert VSX logical operations to vector operations broke X for ppc64le guest

[Andrew Randrianasulu <randrianasulu@gmail.com>]

В сообщении от Thursday 28 February 2019 08:06:45 Mark Cave-Ayland написал(а):
> On 26/02/2019 22:25, Andrew Randrianasulu wrote:
>
> (adding qemu-ppc, Richard and David - please make sure you add the relevant
> maintainer on bug reports, as otherwise due to the high volume of mails to
> the list it's very easy to miss things)

ok


>
> > Hello.
> >
> > I bisected this problem with fonts (and multicolored vertical stripes) in
> > qemu git (ppc64-softmmu)
> >
> > guest@slax:/dev/shm/qemu$ git bisect good
> > 7b8fe477e12b164dda97f79e27b55b805d90384f is the first bad commit
> > commit 7b8fe477e12b164dda97f79e27b55b805d90384f
> > Author: Richard Henderson <richard.henderson@linaro.org>
> > Date:   Fri Feb 15 10:00:46 2019 +0000
> >
> >     target/ppc: convert VSX logical operations to vector operations
> >
> >     Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> >     Acked-by: David Gibson <david@gibson.dropbear.id.au>
> >     Message-Id: <20190215100058.20015-6-mark.cave-ayland@ilande.co.uk>
> >     Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> >
> > :040000 040000 da3024ad2c9dfc3b7170516a8b321ef8c5d5bdf8
> >
> > a0257b9f5880ecc8e7001a59ccaa10407084623f M      target
> >
> >
> > guest@slax:/dev/shm/qemu$ git bisect log
> > git bisect start
> > # good: [32a1a94dd324d33578dca1dc96d7896a0244d768] Update version for
> > v3.1.0 release
> > git bisect good 32a1a94dd324d33578dca1dc96d7896a0244d768
> > # bad: [86c7e2f4a93322a76afea5ee6806a83420d1dfea] Merge remote-tracking
> > branch 'remotes/berrange/tags/authz-core-pull-request' into staging
> > git bisect bad 86c7e2f4a93322a76afea5ee6806a83420d1dfea
> > # good: [95ebd99dcd37b8574426c876502bfcc7c299584b] target/arm: Decode
> > PAuth within disas_data_proc_1src
> > git bisect good 95ebd99dcd37b8574426c876502bfcc7c299584b
> > # good: [268dfefa690b2bdee1f8c5090d2343871cf3467c]
> > hw/microblaze/Makefile.objs: Create configs for petalogix and xilinx
> > boards
> > git bisect good 268dfefa690b2bdee1f8c5090d2343871cf3467c
> > # good: [f5117fd28552fe3fe32ef0495582b1caaef7a28d] hw/mips_cpc: kick a VP
> > when putting it into Run statewq
> > git bisect good f5117fd28552fe3fe32ef0495582b1caaef7a28d
> > # bad: [2e68b8620637a4ee8c79b5724144b726af1e261b] Merge remote-tracking
> > branch 'remotes/dgibson/tags/ppc-for-4.0-20190219' into staging
> > git bisect bad 2e68b8620637a4ee8c79b5724144b726af1e261b
> > # good: [4c668f4a3d684ec133a52d936314379f6edd672e] target/ppc: Remove
> > some #if 0'ed code
> > git bisect good 4c668f4a3d684ec133a52d936314379f6edd672e
> > # bad: [9b5b74da0a07a89ef71c7f7da0b36560a3bac521] target/ppc: Split out
> > VSCR_SAT to a vector field
> > git bisect bad 9b5b74da0a07a89ef71c7f7da0b36560a3bac521
> > # good: [444d6ca301d97de141a502851940943b09a9ebee] spapr/irq: Use the
> > "simple" ICS class for KVM
> > git bisect good 444d6ca301d97de141a502851940943b09a9ebee
> > # bad: [9bb0048ec6f8f3bcc144b2c5769d9301e824f946] target/ppc: convert
> > xxspltw to vector operations
> > git bisect bad 9bb0048ec6f8f3bcc144b2c5769d9301e824f946
> > # good: [471ff3d0257135b938d0a5f2181f22cd753d50de] target/ppc: convert
> > vspltis[bhw] to use vector operations
> > git bisect good 471ff3d0257135b938d0a5f2181f22cd753d50de
> > # bad: [7b8fe477e12b164dda97f79e27b55b805d90384f] target/ppc: convert VSX
> > logical operations to vector operations
> > git bisect bad 7b8fe477e12b164dda97f79e27b55b805d90384f
> > # good: [0f6a6d5db853c0cbe438c1831c70710bfb6530ee] target/ppc: convert
> > vsplt[bhw] to use vector operations
> > git bisect good 0f6a6d5db853c0cbe438c1831c70710bfb6530ee
> > # first bad commit: [7b8fe477e12b164dda97f79e27b55b805d90384f]
> > target/ppc: convert VSX logical operations to vector operations
> > guest@slax:/dev/shm/qemu$
> >
> > configure line:
> > setarch i686 ./configure --target-list=ppc64-softmmu
> >
> > launch line:
> > ppc64-softmmu/qemu-system-ppc64 -display
> > sdl,gl=on -hda /mnt/sdb1/PPC-img/alpine_disk.img
> >
> > where alpine_disk.img is HDD installed Alpine 3.7 for ppc64le with xfce4
> > desktop.
>
> AFAICT the vector instructions converted here are independent of endian, so
> I can't see why this patch on its own would have any effect.
>
> Maybe it could be because the "setarch i686" part forces use of some
> lesser-used 32-bit paths in the vector code - is this required? And do you
> see the same issue on a x86_64 build?

I use 32-bit Slackware userland with x86_64 kerenl - so setarch prevent most of 
configures from detecting my arch wrongly.

Yes, bug was and is present with qemu compiled for x86_64 (inside chroot).
I initially discovered it there, and after dropping -O3 and even march=native, 
and even disabling avx2 via configure switch - moved to bisect.

https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg06414.html

>
>
> ATB,
>
> Mark.