From: "Deucher, Alexander" <Alexander.Deucher@amd.com>
To: "'Joerg Roedel'" <joro@8bytes.org>,
        Bjorn Helgaas <bhelgaas@google.com>
CC: "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Joerg Roedel <jroedel@suse.de>, Daniel Drake <drake@endlessm.com>,
        "Nath, Arindam" <Arindam.Nath@amd.com>
Subject: RE: [PATCH] PCI: Blacklist AMD Stoney GPU devices for ATS
Thread-Topic: [PATCH] PCI: Blacklist AMD Stoney GPU devices for ATS
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Date: Tue, 28 Mar 2017 20:18:26 +0000
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> -----Original Message-----
> From: Joerg Roedel [mailto:joro@8bytes.org]
> Sent: Tuesday, March 28, 2017 8:17 AM
> To: Bjorn Helgaas
> Cc: linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org; Joerg Roedel;
> Daniel Drake; Deucher, Alexander
> Subject: [PATCH] PCI: Blacklist AMD Stoney GPU devices for ATS
> 
> From: Joerg Roedel <jroedel@suse.de>
> 
> ATS is broken on these devices. Under invalidation load, the
> GPU does not reply to invalidations anymore, causing
> Completion-wait loop timeouts on the AMD IOMMU driver side.
> Fix it by not enabling ATS on these devices.
> 
> Note that below mentioned commit is not broken, it just
> triggers the issue because it might cause invalidation
> storms on devices.
> 
> Fixes: b1516a14657a ('iommu/amd: Implement flush queue')
> Reported-by: Daniel Drake <drake@endlessm.com>
> Cc: Daniel Drake <drake@endlessm.com>
> Cc: Alexander Deucher <Alexander.Deucher@amd.com>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>

Did you see Arindam's patch from yesterday[1]?  Not sure which is the proper fix, maybe both?

Alex

[1] - https://lists.freedesktop.org/archives/amd-gfx/2017-March/006862.html

> ---
>  drivers/pci/ats.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index eeb9fb2..711bdb2 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -17,10 +17,18 @@
> 
>  #include "pci.h"
> 
> +static const struct pci_device_id broken_ats_tbl[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, 0x98e4) }, /* AMD Stoney GPU
> part */
> +	{ 0 }
> +};
> +
>  void pci_ats_init(struct pci_dev *dev)
>  {
>  	int pos;
> 
> +	if (pci_match_id(broken_ats_tbl, dev))
> +		return;
> +
>  	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ATS);
>  	if (!pos)
>  		return;
> --
> 1.9.1