Bug 104291

Summary:	Virgl broken on current mesa (17.4+), with nouveau/nv50 as host
Product:	Mesa	Reporter:	Andrew Randrianasulu <randrik>
Component:	Drivers/DRI/nouveau	Assignee:	Nouveau Project <nouveau>
Status:	RESOLVED FIXED	QA Contact:	Nouveau Project <nouveau>
Severity:	normal
Priority:	medium	CC:	fdsfgs
Version:	git
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	glxinfo -l from inside guest gdb log slightly better gdb log X log (from guest, of course) apitrace

Description Andrew Randrianasulu 2017-12-16 17:14:04 UTC

Hello.

Sorry for possibly irrelevant bug report, but I just tested virgl and found it broken - glxinfo works, but glxgears or any gl program segfaults.

On both host and guest (self-assembled live DVD) I have mesa Mesa 17.4.0-devel (git-96fc5fbf23), X server 1.19.5. Host kernel - Linux slax 4.14.3-x64 #18 SMP Sun Dec 3 09:13:07 MSK 2017 x86_64 AMD FX(tm)-4300 Quad-Core Processor AuthenticAMD GNU/Linux, guest kernel - 4.12.0-x64.

Qemu - 2.11. Launch command and output:

qemu-system-x86_64 -M q35 -enable-kvm -cdrom /dev/shm/slax_16_12_2017_test.iso -m 512 -display sdl,gl=on -soundhw es1370 -smp 4 -vga virtio -usbdevice mouse
qemu-system-x86_64: -usbdevice mouse: '-usbdevice' is deprecated, please use '-device usb-...' instead
gl_version 33 - core profile enabled

startx inside guest works, glxinfo shows virgl as renderer, but glxgears or any gl program (chromium BSU [old arcade game], glblur from xscreensavers) segfaults.

At some point it was working better, but it was long ago .... (16.02.2016, to be prescie).

I also run into assertion on qemu side, described here: 
https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg05461.html

Because I had only dvd image connected as dvd rom - nothing bad happened, but be aware about this abort if you connect real hard disk ....

Comment 1 Andrew Randrianasulu 2017-12-16 17:15:34 UTC

One more comment - while both kernels are 64-bit - whole userspace for guest and host are just 32-bit binaries. It may play some role.

Comment 2 Ilia Mirkin 2017-12-16 17:18:18 UTC

If you can capture an apitrace of qemu that replays incorrectly on nouveau but correctly on other hardware, then this is a nouveau bug.

If virgl / virglrenderer code crashes (or generates an incorrect GL operation sequence), then it's a virgl bug.

Comment 3 Andrew Randrianasulu 2017-12-16 17:23:52 UTC

Created attachment 136219 [details]
glxinfo -l from inside guest

Comment 4 Andrew Randrianasulu 2017-12-16 17:27:59 UTC

Created attachment 136220 [details]
gdb log

Unfortunately, I stripped debug symbols for smaller file sizes. I can recompile mesa with debug symbols, but it will take some time.

Comment 5 Ilia Mirkin 2017-12-16 17:31:09 UTC

If it crashes inside the guest, then it's nothing to do with nouveau. Most likely.

Comment 6 Andrew Randrianasulu 2017-12-16 17:35:12 UTC

(In reply to Ilia Mirkin from comment #5)
> If it crashes inside the guest, then it's nothing to do with nouveau. Most
> likely.

ya, but I was unable to find virgl as specific component  in bugzilla, so I just  added bug to nouveau. Don't feel blamed. (and  after swithcing virtual desktops whole image inside qemu just become real black ..I killed this VM)

Comment 7 Andrew Randrianasulu 2017-12-16 17:43:49 UTC

It also doesn't work with  LIBGL_ALWAYS_SOFTWARE=1 (llvmpipe). So, yes, not nouveau bug....

Comment 8 Andrew Randrianasulu 2017-12-16 17:55:43 UTC

Created attachment 136221 [details]
slightly better gdb log

Comment 9 Andrew Randrianasulu 2017-12-16 18:12:23 UTC

Created attachment 136222 [details]
X log (from guest, of course)

Comment 10 Andrew Randrianasulu 2017-12-16 18:28:17 UTC

Created attachment 136223 [details]
apitrace

Comment 11 Andrew Randrianasulu 2017-12-19 22:37:43 UTC

I tried few older mesa releases (17.1.10 - without llvm, 17.2.7 and 17.3.0 - with llvm 5.0.0), and they all segfaults :/

This is kinda strange, because according to this bugreport it was working in 17.1-dev era:

https://bugzilla.redhat.com/show_bug.cgi?id=1426549

I tried disabling PageFlipping (not sure if it makes any sense for VM), and switching dri mode to dri3. Nothing helped :/

Comment 12 Andrew Randrianasulu 2018-04-30 11:59:38 UTC

Sorry, it works now (Mesa 18.2.0-devel (git-96ed3714fc) for both guest and host). Apparently, I just forgot to mount /dev/shm in initscripts in guest, and dri3  failed.

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