Message-ID: <58b874c2ecd865ff5abc52e037f63d3a1cc7ecc5.camel@linux.intel.com>
Subject: Re: Issue with Ath9k/PCI passthrough
From:   James Prestwood <james.prestwood@linux.intel.com>
To:     Christian Lamparter <chunkeey@gmail.com>
Cc:     linux-wireless@vger.kernel.org
Date:   Mon, 07 Jan 2019 10:53:49 -0800
In-Reply-To: <3155667.IrPEAHJHAv@debian64>
References: <6cc1ddae1bab8f71daa07c2c7082354507496f5f.camel@linux.intel.com>
         <3155667.IrPEAHJHAv@debian64>
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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?

> 
> <
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/quirks.c#n3400
> >
> 
> I know that the AR93xx and AR94xx cards have problems with PCIe
> Passthrough:
> <https://patchwork.kernel.org/patch/9141239/> and
> <https://www.spinics.net/lists/linux-pci/msg34797.html> so maybe you
> can get
> it to work, once you add a entry to the fixup list.
> 
> Regards,
> Christian
> 
>