Message-ID: <1373300262.2602.22.camel@ul30vt.home>
Subject: Re: [PATCH v2 0/3] pci: ACS fixes & quirks
From: Alex Williamson <alex.williamson@redhat.com>
To: bhelgaas@google.com
Cc: linux-pci@vger.kernel.org, joro@8bytes.org, andihartmann@01019freenet.de,
        linux-kernel@vger.kernel.org
Date: Mon, 08 Jul 2013 10:17:42 -0600
In-Reply-To: <20130627222159.16564.38166.stgit@bling.home>
References: <20130627222159.16564.38166.stgit@bling.home>
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Ping.  Comments?

On Thu, 2013-06-27 at 16:39 -0600, Alex Williamson wrote:
> 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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