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From: Christoph Hellwig <hch@lst.de>
To: Jon Derrick <jonathan.derrick@intel.com>
Cc: iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org,
	Bjorn Helgaas <helgaas@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Keith Busch <kbusch@kernel.org>, Joerg Roedel <joro@8bytes.org>,
	Christoph Hellwig <hch@lst.de>,
	David Woodhouse <dwmw2@infradead.org>,
	Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: [RFC 4/5] PCI: vmd: Stop overriding dma_map_ops
Date: Thu, 9 Jan 2020 15:36:13 +0100	[thread overview]
Message-ID: <20200109143613.GC22656@lst.de> (raw)
In-Reply-To: <1577823863-3303-5-git-send-email-jonathan.derrick@intel.com>

On Tue, Dec 31, 2019 at 01:24:22PM -0700, Jon Derrick wrote:
> Devices on the VMD domain use the VMD endpoint's requester-id and have
> been relying on the VMD endpoint's dma operations. The downside of this
> was that VMD domain devices would use the VMD endpoint's attributes when
> doing DMA and IOMMU mapping. We can be smarter about this by only using
> the VMD endpoint when mapping and providing the correct child device's
> attributes during dma operations.
> 
> This patch adds a new dma alias mechanism by adding a hint to a pci_dev
> to point to a singular DMA requester's pci_dev. This integrates into the
> existing dma alias infrastructure to reduce the impact of the changes
> required to support this mode.

If we want to lift this check into common code I think it should go
into struct device, as that is what DMA operates on normally.  That
being said given that this insane hack only exists for braindamage in
Intel hardware I'd rather keep it as isolated as possible.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Jon Derrick <jonathan.derrick@intel.com>
Cc: linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org,
	Bjorn Helgaas <helgaas@kernel.org>,
	Keith Busch <kbusch@kernel.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [RFC 4/5] PCI: vmd: Stop overriding dma_map_ops
Date: Thu, 9 Jan 2020 15:36:13 +0100	[thread overview]
Message-ID: <20200109143613.GC22656@lst.de> (raw)
In-Reply-To: <1577823863-3303-5-git-send-email-jonathan.derrick@intel.com>

On Tue, Dec 31, 2019 at 01:24:22PM -0700, Jon Derrick wrote:
> Devices on the VMD domain use the VMD endpoint's requester-id and have
> been relying on the VMD endpoint's dma operations. The downside of this
> was that VMD domain devices would use the VMD endpoint's attributes when
> doing DMA and IOMMU mapping. We can be smarter about this by only using
> the VMD endpoint when mapping and providing the correct child device's
> attributes during dma operations.
> 
> This patch adds a new dma alias mechanism by adding a hint to a pci_dev
> to point to a singular DMA requester's pci_dev. This integrates into the
> existing dma alias infrastructure to reduce the impact of the changes
> required to support this mode.

If we want to lift this check into common code I think it should go
into struct device, as that is what DMA operates on normally.  That
being said given that this insane hack only exists for braindamage in
Intel hardware I'd rather keep it as isolated as possible.
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iommu@lists.linux-foundation.org
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  parent reply	other threads:[~2020-01-09 14:36 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-31 20:24 [RFC 0/5] Clean up VMD DMA Map Ops Jon Derrick
2019-12-31 20:24 ` Jon Derrick
2019-12-31 20:24 ` [RFC 1/5] iommu: Remove device link to group on failure Jon Derrick
2019-12-31 20:24   ` Jon Derrick
2020-01-01  3:59   ` Lu Baolu
2020-01-01  3:59     ` Lu Baolu
2019-12-31 20:24 ` [RFC 2/5] iommu/vt-d: Unlink device if failed to add to group Jon Derrick
2019-12-31 20:24   ` Jon Derrick
2020-01-01  4:05   ` Lu Baolu
2020-01-01  4:05     ` Lu Baolu
2020-01-12  1:36   ` Lu Baolu
2020-01-12  1:36     ` Lu Baolu
2020-01-13 12:20     ` Joerg Roedel
2020-01-13 12:20       ` Joerg Roedel
2020-01-14  1:58       ` Lu Baolu
2020-01-14  1:58         ` Lu Baolu
2019-12-31 20:24 ` [RFC 3/5] x86/PCI: Expose VMD's device in pci_sysdata Jon Derrick
2019-12-31 20:24   ` Jon Derrick
2020-01-09 14:33   ` Christoph Hellwig
2020-01-09 14:33     ` Christoph Hellwig
2020-01-09 15:06     ` Derrick, Jonathan
2020-01-09 15:06       ` Derrick, Jonathan
2020-01-09 16:45     ` Derrick, Jonathan
2020-01-09 16:45       ` Derrick, Jonathan
2019-12-31 20:24 ` [RFC 4/5] PCI: vmd: Stop overriding dma_map_ops Jon Derrick
2019-12-31 20:24   ` Jon Derrick
2020-01-03 15:00   ` kbuild test robot
2020-01-04  9:39   ` kbuild test robot
2020-01-09 14:36   ` Christoph Hellwig [this message]
2020-01-09 14:36     ` Christoph Hellwig
2020-01-09 15:08     ` Derrick, Jonathan
2020-01-09 15:08       ` Derrick, Jonathan
2019-12-31 20:24 ` [RFC 5/5] x86/PCI: Remove unused X86_DEV_DMA_OPS Jon Derrick
2019-12-31 20:24   ` Jon Derrick
2020-01-09 14:37   ` Christoph Hellwig
2020-01-09 14:37     ` Christoph Hellwig
2020-01-09 15:06     ` Derrick, Jonathan
2020-01-09 15:06       ` Derrick, Jonathan
2020-01-07 13:41 ` [RFC 0/5] Clean up VMD DMA Map Ops Joerg Roedel
2020-01-07 13:41   ` Joerg Roedel

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