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From: Jason Gunthorpe <jgg@nvidia.com>
To: Baolu Lu <baolu.lu@linux.intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	Jacob Pan <jacob.jun.pan@linux.intel.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
	Joerg Roedel <joro@8bytes.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	Christoph Hellwig <hch@infradead.org>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"will@kernel.org" <will@kernel.org>,
	"Liu, Yi L" <yi.l.liu@intel.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	Eric Auger <eric.auger@redhat.com>
Subject: Re: [PATCH v4 1/6] iommu: Add a per domain PASID for DMA API
Date: Tue, 31 May 2022 13:03:09 -0300	[thread overview]
Message-ID: <20220531160309.GG1343366@nvidia.com> (raw)
In-Reply-To: <628aa885-dd12-8bcd-bfc6-446345bf69ed@linux.intel.com>

On Tue, May 31, 2022 at 08:45:28PM +0800, Baolu Lu wrote:

> My understanding is that device driver owns its PASID policy.

I'm not sure this is actually useful, the core code should provide the
allocator as I can't think of any device that actually needs a special
allocator.

> If ENQCMD is supported on the device, the PASIDs should be allocated
> through ioasid_alloc(). Otherwise, the whole PASID pool is managed
> by the device driver.

This is OK only if we know in-advance that the device needs a global
PASID. ENQCMD is one reason, maybe there are others down the road.

Better to make this core code policy.

Jason

WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe via iommu <iommu@lists.linux-foundation.org>
To: Baolu Lu <baolu.lu@linux.intel.com>
Cc: "vkoul@kernel.org" <vkoul@kernel.org>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"will@kernel.org" <will@kernel.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
	David Woodhouse <dwmw2@infradead.org>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>
Subject: Re: [PATCH v4 1/6] iommu: Add a per domain PASID for DMA API
Date: Tue, 31 May 2022 13:03:09 -0300	[thread overview]
Message-ID: <20220531160309.GG1343366@nvidia.com> (raw)
In-Reply-To: <628aa885-dd12-8bcd-bfc6-446345bf69ed@linux.intel.com>

On Tue, May 31, 2022 at 08:45:28PM +0800, Baolu Lu wrote:

> My understanding is that device driver owns its PASID policy.

I'm not sure this is actually useful, the core code should provide the
allocator as I can't think of any device that actually needs a special
allocator.

> If ENQCMD is supported on the device, the PASIDs should be allocated
> through ioasid_alloc(). Otherwise, the whole PASID pool is managed
> by the device driver.

This is OK only if we know in-advance that the device needs a global
PASID. ENQCMD is one reason, maybe there are others down the road.

Better to make this core code policy.

Jason
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2022-05-31 16:03 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-18 18:21 [PATCH v4 0/6] Enable PASID for DMA API users Jacob Pan
2022-05-18 18:21 ` Jacob Pan
2022-05-18 18:21 ` [PATCH v4 1/6] iommu: Add a per domain PASID for DMA API Jacob Pan
2022-05-18 18:21   ` Jacob Pan
2022-05-19  6:50   ` Baolu Lu
2022-05-19  6:50     ` Baolu Lu
2022-05-24 13:50   ` Jason Gunthorpe
2022-05-24 13:50     ` Jason Gunthorpe via iommu
2022-05-24 15:17     ` Jacob Pan
2022-05-24 15:17       ` Jacob Pan
2022-05-30 12:22       ` Jason Gunthorpe
2022-05-30 12:22         ` Jason Gunthorpe via iommu
2022-05-31 10:12         ` Tian, Kevin
2022-05-31 10:12           ` Tian, Kevin
2022-05-31 12:45           ` Baolu Lu
2022-05-31 12:45             ` Baolu Lu
2022-05-31 16:03             ` Jason Gunthorpe [this message]
2022-05-31 16:03               ` Jason Gunthorpe via iommu
2022-05-31 17:29             ` Jacob Pan
2022-05-31 17:29               ` Jacob Pan
2022-05-31 19:05               ` Jason Gunthorpe
2022-05-31 19:05                 ` Jason Gunthorpe via iommu
2022-05-31 20:44                 ` Jacob Pan
2022-05-31 20:44                   ` Jacob Pan
2022-06-01  1:50                   ` Tian, Kevin
2022-06-01  1:50                     ` Tian, Kevin
2022-06-01  1:43               ` Tian, Kevin
2022-06-01  1:43                 ` Tian, Kevin
2022-06-01  9:37                 ` Baolu Lu
2022-06-01  9:37                   ` Baolu Lu
2022-06-01 10:05                   ` Tian, Kevin
2022-06-01 10:05                     ` Tian, Kevin
2022-05-18 18:21 ` [PATCH v4 2/6] iommu: Add a helper to do PASID lookup from domain Jacob Pan
2022-05-18 18:21   ` Jacob Pan
2022-05-19  6:41   ` Baolu Lu
2022-05-19  6:41     ` Baolu Lu
2022-05-19 20:10     ` Jacob Pan
2022-05-19 20:10       ` Jacob Pan
2022-05-19  6:48   ` Christoph Hellwig
2022-05-19  6:48     ` Christoph Hellwig
2022-05-20 15:18     ` Jacob Pan
2022-05-20 15:18       ` Jacob Pan
2022-05-23  7:55   ` Tian, Kevin
2022-05-23  7:55     ` Tian, Kevin
2022-05-23  9:14   ` Tian, Kevin
2022-05-23  9:14     ` Tian, Kevin
2022-05-23 18:01     ` Jacob Pan
2022-05-23 18:01       ` Jacob Pan
2022-05-18 18:21 ` [PATCH v4 3/6] iommu/vt-d: Implement domain ops for attach_dev_pasid Jacob Pan
2022-05-18 18:21   ` Jacob Pan
2022-05-24 13:51   ` Jason Gunthorpe
2022-05-24 13:51     ` Jason Gunthorpe via iommu
2022-05-24 16:12     ` Jacob Pan
2022-05-24 16:12       ` Jacob Pan
2022-05-24 18:02       ` Jason Gunthorpe
2022-05-24 18:02         ` Jason Gunthorpe via iommu
2022-05-24 20:45         ` Jacob Pan
2022-05-24 20:45           ` Jacob Pan
2022-05-24 21:10           ` Jason Gunthorpe
2022-05-24 21:10             ` Jason Gunthorpe via iommu
2022-05-18 18:21 ` [PATCH v4 4/6] iommu: Add PASID support for DMA mapping API users Jacob Pan
2022-05-18 18:21   ` Jacob Pan
2022-05-23  8:25   ` Tian, Kevin
2022-05-23  8:25     ` Tian, Kevin
2022-05-23 15:23     ` Jacob Pan
2022-05-23 15:23       ` Jacob Pan
2022-05-18 18:21 ` [PATCH v4 5/6] dmaengine: idxd: Use DMA API for in-kernel DMA with PASID Jacob Pan
2022-05-18 18:21   ` Jacob Pan
2022-05-18 18:21 ` [PATCH v4 6/6] iommu/vt-d: Delete unused SVM flag Jacob Pan
2022-05-18 18:21   ` Jacob Pan

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