linux-kernel - [PATCH v2 0/3] pci: ACS fixes & quirks

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Message-ID: <20130627222159.16564.38166.stgit@bling.home>
Date:	Thu, 27 Jun 2013 16:39:41 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	bhelgaas@...gle.com
Cc:	linux-pci@...r.kernel.org, joro@...tes.org,
	andihartmann@...19freenet.de, linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/3] pci: ACS fixes & quirks

v2:

Revised patch 1/ to match comments from Bjorn.  PCIe event collectors
and PCIe-to-PCI bridges now indicate that they do not support ACS.
I've reached out to try to get clarification on this, but I think it's
reasonable to proceed with a conservative approach until then.  I also
added PCI-to-PCIe bridges for the sake of being complete.  Also added
more comments about the purpose and behavior of pci_acs_enabled().  If
I've overlooked anything else that needs to be addressed, please let
me know.

Patch 2/ had no comments, it's unchanged.

Patch 3/ is added.  This was sent as an RFC nearly a year ago and
Joerg confirmed for us that these devices do not support p2p on AMD
systems with AMD IOMMU.  We can't simply use iommu_present() to test
for an IOMMU because it's setup just after we need this function.  
Instead we test for the ACPI IVRS table that describes the IOMMU.  It
would probably suffice to skip an actual AMD IOMMU check, but I don't
want it to later come bite us if these ASICs get re-used, maybe with
a different IOMMU, and don't make the same guarantees.

Joerg, I was also curious back when we investigated this patch if the
same rules hold true for these other southbridge devices:

1002:43a0 SB700/SB800/SB900 PCI to PCI bridge (PCIE port 0)
1002:43a1 SB700/SB800/SB900 PCI to PCI bridge (PCIE port 1)
1002:43a2 SB900 PCI to PCI bridge (PCIE port 2)
1002:43a3 SB900 PCI to PCI bridge (PCIE port 3)

If you remember or have contacts to poke, I'd be happy to follow-up
with another patch to add them.  Thanks,

Alex

---

Alex Williamson (3):
      pci: Fix flaw in pci_acs_enabled()
      pci: Differentiate ACS controllable from enabled
      pci: ACS quirk for AMD southbridge

 drivers/pci/pci.c    |   93 +++++++++++++++++++++++++++++++++++++++++---------
 drivers/pci/quirks.c |   50 +++++++++++++++++++++++++++
 2 files changed, 127 insertions(+), 16 deletions(-)
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