Re: [PATCH 2/2] PCI: Disable ATS for specific Intel IPU E2000 devices

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Aug 16, 2023 at 05:21:15PM +0000, Bartosz Pawlowski wrote:
> There is a HW issue in A and B steppings of Intel IPU E2000 that it
> expects wrong endianness in ATS invalidation message body. This problem
> can lead to outdated translations being returned as valid and finally
> cause system instability.
> 
> In order to prevent such issues introduce quirk_intel_e2000_no_ats()
> function to disable ATS for vulnerable IPU E2000 devices.
> 
> Signed-off-by: Bartosz Pawlowski <bartosz.pawlowski@intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>

Andy, Alexander, would you please reiterate your reviewed-by on the
mailing list?  I try to avoid relying on internal reviews collected by
the author.  Those are great and I'm glad they happen, but it's good
if they also appear as part of the public conversation on the mailing
list.

> ---
>  drivers/pci/quirks.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index a900546d8d45..9aa1e0148ed2 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -5550,6 +5550,28 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x7347, quirk_amd_harvest_no_ats);
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x734f, quirk_amd_harvest_no_ats);
>  /* AMD Raven platform iGPU */
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x15d8, quirk_amd_harvest_no_ats);
> +
> +/*
> + * Intel IPU E2000 revisions before C0 implement incorrect endianness
> + * in ATS Invalidate Request message body. Although there is existing software
> + * workaround for this issue, it is not functionally complete (no 5-lvl paging
> + * support) and it requires changes in all IOMMU implementations supporting
> + * ATS. Therefore, disabling ATS seems to be more reasonable.
> + */
> +static void quirk_intel_e2000_no_ats(struct pci_dev *pdev)
> +{
> +	if (pdev->revision < 0x20)
> +		quirk_no_ats(pdev);
> +}
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1451, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1452, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1453, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1454, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1455, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1457, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1459, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x145a, quirk_intel_e2000_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x145c, quirk_intel_e2000_no_ats);
>  #endif /* CONFIG_PCI_ATS */
>  
>  /* Freescale PCIe doesn't support MSI in RC mode */
> -- 
> 2.41.0
> 
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