[vfio-users] vfio pass through only works once after reboot - more tests

[Karsten Elfenbein]

Hi,

I replaced the GF460 with an GF950 and it works fine over multiple VM restarts.

Just ran into the performance regression on the 4.2 kernel and went
back to 4.1.x.
Currently I'm stuck with the code 43 error but I will try the patch
from the other thread.

Karsten


2015-09-17 23:37 GMT+02:00 Alex Williamson <alex.williamson at redhat.com>:
> On Thu, 2015-09-17 at 22:56 +0200, Karsten Elfenbein wrote:
>> Hi,
>>
>> after my first tries in
>> http://lists.nongnu.org/archive/html/qemu-discuss/2015-09/msg00003.html
>> I did an other round of tests.
>>
>> I made the GF460 the primary card and put the GF970 into vfio. With
>> that config the VM could start and use the card multiple times without
>> rebooting. (vfio is chowned to me)
>>
>> The only bad output I get from qemu while running the gf970 in the VM is:
>> qemu-system-x86_64: vfio_pci_write_config(0000:06:00.0, 0x418,
>> 0xe0000, 0x4) failed: Bad address
>>
>> Then I switched back to the GF460 for the VM and get some more of these lines:
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x13c, 0x4)
>> failed: Bad address
>
> Hmm, "Bad address" is -EFAULT from the kernel.  We can get that if the
> offset is outside the size of config space for the device, copying
> faults to/from userspace, or if we do an unaligned access.  Are you
> trying to use q35?  I don't know how else we'd get config accesses above
> 0xff.  Can you send lspci -v for the GPUs and lspci -tv for the system?
>
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x13c,
>> 0x3ffffff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x150, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x150,
>> 0xfffffff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x48c,
>> 0x118008c, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x45c, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x45c,
>> 0xfffffff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x158, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x158,
>> 0xfffffff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x610, 0x5,
>> 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x418,
>> 0xe0000, 0x4) failed: Bad address
>> The second boot looks the same but the card does not bring a signal.
>> (not even the card bios comes up)
>>
>> Installing the Nvidia driver with the GF460 crashed the Windows 10 VM
>> with more if these lines:
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x60c, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x610, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x138, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x138,
>> 0xfffffff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x460, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x460, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x150, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x18c, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x4a8, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x4a4, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x138, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x138,
>> 0xf007fff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x460, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x460,
>> 0xfffffff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_write_config(0000:03:00.0, 0x138,
>> 0xfffffff2, 0x4) failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x4a8, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x4a4, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x4a8, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x4a4, 0x4)
>> failed: Bad address
>> qemu-system-x86_64: vfio_pci_read_config(0000:03:00.0, 0x4a8, 0x4)
>> failed: Bad address
>>
>>
>> Just wondering if it is possible to get the card running or better to
>> just grab a GF950.
>
> That seems like a nice upgrade.  If the 460 is all the graphics you
> need, I'd be tempted to move to a 750 just for the better power
> efficiency.
>