Re: Issue with Ath9k/PCI passthrough

[James Prestwood <james.prestwood@linux.intel.com>]

On Mon, 2019-01-07 at 21:00 +0100, Christian Lamparter wrote:
> On Monday, January 7, 2019 7:53:49 PM CET James Prestwood wrote:
> > On Mon, 2019-01-07 at 19:24 +0100, Christian Lamparter wrote:
> > > On Monday, January 7, 2019 6:55:48 PM CET James Prestwood wrote:
> > > > Hi,
> > > > 
> > > > I am passing through PCI wireless adapters into a qemu VM and I
> > > > am
> > > > seeing my host machine lock up/freeze when starting qemu if I
> > > > try
> > > > and
> > > > pass through an Atheros AR5B22 PCI card. After reboot I don't
> > > > see
> > > > anything suspicious in /var/log/kern.log, although I don't
> > > > really
> > > > know
> > > > what to look for either (or maybe there is another log to look
> > > > at?). I
> > > > have successfully done PCI passthrough with both an Intel 7260
> > > > and
> > > > 3160. Its whenever I add the Atheros card into the mix (or by
> > > > itself) I
> > > > get this lockup when starting the VM.
> > > > 
> > > > I have enabled the Ath9k drivers when building the kernel (same
> > > > as
> > > > with
> > > > Intel cards). This page I read online (
> > > > https://wiki.debian.org/ath9k)
> > > > said the Ath9k cards don't require firmware like the Intel
> > > > cards
> > > > do, so
> > > > I have not added any firmware binaries for this card into the
> > > > kernel
> > > > build. I also tried turning on the Ath9k debugging but saw no
> > > > additional prints in kern.log.
> > > > 
> > > > With PCI passthrough there is some configuration required, like
> > > > substituting the drivers for the vfio-pci driver on the host
> > > > machine,
> > > > so it could be completely unrelated to the Ath9k driver. Still,
> > > > I
> > > > was
> > > > hoping that someone more knowledgeable than me may know whats
> > > > going
> > > > on,
> > > > or at least where to look. The fact that the Intel cards work
> > > > fine
> > > > was
> > > > what made me think it could be a driver problem.
> > > > 
> > > > I am more or less following this guide (except with wifi
> > > > adapters
> > > > rather than GPU):
> > > > https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVMF
> > > > 
> > > 
> > > You could be a victim of:
> > > 
> > > > /*
> > > > * Some Atheros AR9xxx and QCA988x chips do not behave after a
> > > > bus
> > > > reset.
> > > > * The device will throw a Link Down error on AER-capable
> > > > systems
> > > > and
> > > > * regardless of AER, config space of the device is never
> > > > accessible
> > > > again
> > > > * and typically causes the system to hang or reset when access
> > > > is
> > > > attempted.
> > > > * http://www.spinics.net/lists/linux-pci/msg34797.html
> > > > */
> > > > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0030,
> > > > quirk_no_bus_reset);
> > > > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0032,
> > > > quirk_no_bus_reset);
> > > > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003c,
> > > > quirk_no_bus_reset);
> > > > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0033,
> > > > quirk_no_bus_reset);
> > 
> > Adding this to my guest kernel and rebuilding didn't change
> > anything:
> > 
> > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0034,
> > quirk_no_bus_reset);
> > 
> > But would I need to make this change on the host kernel as well?
> 
> It can matter. I have a mainboard that does a bus reset before
> booting the kernel and as a result I was never able to get a
> ath10k/ath9k card working on the machine. The kernel would just
> get suck either during decompressing or shortly after in random
> places. It had no issues with intel or broadcom cards.

Looks like I did indeed need the change in the host kernel! No lockup
and I see the Ath9k inside the VM. Thanks!

Is this something that should be upstreamed (adding the vendor ID to
that list)? If so do you know the list by chance? A quick google it
would seem https://patchwork.kernel.org/project/linux-pci/list/ is the
right place?

Thanks,
James