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From:   "Deucher, Alexander" <Alexander.Deucher@amd.com>
To:     Bjorn Helgaas <helgaas@kernel.org>,
        Nikolai Kostrigin <nickel@altlinux.org>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@amd.com>,
        "Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
        "Kuehling, Felix" <Felix.Kuehling@amd.com>,
        "Koenig, Christian" <Christian.Koenig@amd.com>
CC:     "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "jroedel@suse.de" <jroedel@suse.de>
Subject: RE: [PATCH RESEND 1/1] PCI: Add ATS-disable quirk for AMD Radeon R7
 GPUs
Thread-Topic: [PATCH RESEND 1/1] PCI: Add ATS-disable quirk for AMD Radeon R7
 GPUs
Thread-Index: AQHU7x+DAmu/NcPAdEyJYqSbzdz726Y1cLAw
Date:   Wed, 10 Apr 2019 14:46:37 +0000
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References: <20190408103725.30426-1-nickel@altlinux.org>
 <20190408103725.30426-2-nickel@altlinux.org>
 <20190409215927.GC256045@google.com>
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> -----Original Message-----
> From: Bjorn Helgaas <helgaas@kernel.org>
> Sent: Tuesday, April 9, 2019 5:59 PM
> To: Nikolai Kostrigin <nickel@altlinux.org>
> Cc: linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org;
> jroedel@suse.de; Deucher, Alexander <Alexander.Deucher@amd.com>
> Subject: Re: [PATCH RESEND 1/1] PCI: Add ATS-disable quirk for AMD Radeon
> R7 GPUs
>=20
> [+cc Alex]
>=20
> This claims to be a resend, but I don't see a previous posting.
>=20
> There *was* discussion when the quirk was added two years ago for a
> different device.  As part of that, Alex thought only that device would b=
e
> affected and ATS was validated on other GPUs:
>=20
>=20
> https://lore.kernel.org/lkml/BN6PR12MB165278346BE8A76B1E4412AFF7EA0
> @BN6PR12MB1652.namprd12.prod.outlook.com/
>=20
> On Mon, Apr 08, 2019 at 01:37:25PM +0300, Nikolai Kostrigin wrote:
> > ATS is broken on this hardware (at least for Stoney Ridge based
> > laptop) and causes IOMMU stalls and system failure. Disable ATS on
> > these devices to make them usable again with IOMMU enabled Thanks to
> > Joerg Roedel <jroedel@suse.de> for help.
> >
> > https://bugzilla.kernel.org/show_bug.cgi?id=3D194521
> >

+ a few AMD people

Seeing this bug makes it more clear.  I don't think this is a problem with =
the GPU.  I think it's a problem with either the sbios or iommu.  I think t=
he original quirk added for stoney (0x98e4) is probably wrong as well.  I s=
uspect we need a quirk for a particular laptop or sbios versions.  We valid=
ated ATS extensively with Carrizo based systems (the system in the bug repo=
rt above is Carrizo based) since it is the basis of our ROCm support on APU=
s.  We have also been involved in tons of Linux OEM preloads with both Carr=
izo and Stoney based APUs in combination with TOPAZ dGPUs (0x6900) and have=
n't seen this issue in those programs.  We also have TOPAZ dGPUs used in OE=
M programs with Intel chipsets and haven't seen the issue.  I suspect since=
 windows does not use the IOMMU by default, the sbios settings may not be w=
ell validated on certain windows only skus.  I'd rather make these DMI matc=
hes or something like that for the platform or at the very least match the =
SSIDs as well.

Alex

> > Signed-off-by: Nikolai Kostrigin <nickel@altlinux.org>
>=20
> Joerg, I'm happy to merge this if you would review or ack it.  I don't kn=
ow
> enough to conclude that this is the root cause.  It'd be nice to have an =
actual
> AMD erratum.  Maybe it would even have a list of affected devices so we
> could get them all at once so people wouldn't have to trip over them one =
by
> one.
>=20
> > ---
> >  drivers/pci/quirks.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index
> > 4700d24e5d55..abb2532e16bf 100644
> > --- a/drivers/pci/quirks.c
> > +++ b/drivers/pci/quirks.c
> > @@ -4876,6 +4876,7 @@ static void quirk_no_ats(struct pci_dev *pdev)
> >
> >  /* AMD Stoney platform GPU */
> >  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x98e4, quirk_no_ats);
> > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x6900,
> quirk_no_ats);
> >  #endif /* CONFIG_PCI_ATS */
> >
> >  /* Freescale PCIe doesn't support MSI in RC mode */
> > --
> > 2.21.0
> >