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

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Message-ID: <20130723201948.GA19765@google.com>
Date:	Tue, 23 Jul 2013 14:19:48 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Alex Williamson <alex.williamson@...hat.com>
Cc:	linux-pci@...r.kernel.org, joro@...tes.org,
	andihartmann@...19freenet.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] pci: ACS fixes & quirks

On Thu, Jun 27, 2013 at 04:39:41PM -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

Applied to pci/aw-acs-fixes-v2 for v3.12, thanks!
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