From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Robin Murphy <robin.murphy@arm.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>,
Joerg Roedel <joro@8bytes.org>,
Christoph Hellwig <hch@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Jean-Philippe Brucker <jean-philippe@linaro.com>,
"Luck, Tony" <tony.luck@intel.com>,
"Jiang, Dave" <dave.jiang@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"Zanussi, Tom" <tom.zanussi@intel.com>,
"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
"Williams, Dan J" <dan.j.williams@intel.com>
Subject: Re: [PATCH v2 5/8] iommu: Add PASID support for DMA mapping API users
Date: Wed, 16 Mar 2022 11:07:48 -0300 [thread overview]
Message-ID: <20220316140748.GF11336@nvidia.com> (raw)
In-Reply-To: <BN9PR11MB527697CA21B1D28BBD0BE0DC8C119@BN9PR11MB5276.namprd11.prod.outlook.com>
On Wed, Mar 16, 2022 at 08:41:27AM +0000, Tian, Kevin wrote:
> 1) When the kernel wants a more scalable way of using IDXD e.g. having
> multiple CPUs simultaneously submitting works in a lockless way to a
> shared work queue via a new instruction (ENQCMD) which carries
> PASID.
IMHO the misdesign is the CPU can't submit work with ENQCMD from
kernel space that will do DMA on the RID.
> 2) When the host wants to share a workqueue between multiple VMs.
> In that case the virtual IDXD device exposed to each VM will only support
> the shared workqueue mode. Only in this case the DMA API in the
> guest must be attached by a PASID as ENQCMD is the only way to submit
> works.
It is the same issue - if ENQCMD had 'excute on the RID' then the
virtualization layer could translate that to 'execute on this PASID
setup by the hypervisor' and the kernel would not see additional
differences between SIOV and physical devices. IMHO mandatory kernel
PASID support in the guest just to support the kernel doing DMA to a
device is not nice.
Jason
next prev parent reply other threads:[~2022-03-16 14:07 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-15 5:07 [PATCH v2 0/8] Enable PASID for DMA API users Jacob Pan
2022-03-15 5:07 ` [PATCH v2 1/8] iommu: Assign per device max PASID Jacob Pan
2022-03-15 5:07 ` [PATCH v2 2/8] iommu: Add attach/detach_dev_pasid domain ops Jacob Pan
2022-03-15 10:24 ` Tian, Kevin
2022-03-15 11:26 ` Jean-Philippe Brucker
2022-03-15 11:49 ` Tian, Kevin
2022-03-15 16:11 ` Jacob Pan
2022-03-18 12:01 ` Lu Baolu
2022-03-18 13:50 ` Jason Gunthorpe
2022-03-18 11:52 ` Lu Baolu
2022-03-18 13:48 ` Jason Gunthorpe
2022-03-15 5:07 ` [PATCH v2 3/8] iommu/vt-d: Implement device_pasid domain attach ops Jacob Pan
2022-03-15 10:33 ` Tian, Kevin
2022-03-15 22:23 ` Jacob Pan
2022-03-15 14:33 ` Jason Gunthorpe
2022-03-15 22:36 ` Jacob Pan
2022-03-15 23:04 ` Jason Gunthorpe
2022-03-16 20:50 ` Jacob Pan
2022-03-16 22:15 ` Jason Gunthorpe
2022-03-16 22:23 ` Luck, Tony
2022-03-17 0:04 ` Jason Gunthorpe
2022-03-18 5:47 ` Tian, Kevin
2022-03-18 13:47 ` Jason Gunthorpe
2022-03-17 0:49 ` Jacob Pan
2022-03-17 13:23 ` Jason Gunthorpe
2022-03-17 18:23 ` Jacob Pan
2022-03-16 7:41 ` Tian, Kevin
2022-03-16 21:01 ` Jacob Pan
2022-03-18 5:33 ` Tian, Kevin
2022-03-28 21:41 ` Jacob Pan
2022-03-16 7:39 ` Tian, Kevin
2022-03-16 20:51 ` Jacob Pan
2022-03-15 5:07 ` [PATCH v2 4/8] iommu/vt-d: Use device_pasid attach op for RID2PASID Jacob Pan
2022-03-16 7:54 ` Tian, Kevin
2022-03-17 20:45 ` Jacob Pan
2022-03-15 5:07 ` [PATCH v2 5/8] iommu: Add PASID support for DMA mapping API users Jacob Pan
2022-03-15 11:16 ` Robin Murphy
2022-03-15 14:22 ` Jason Gunthorpe
2022-03-15 16:31 ` Jacob Pan
2022-03-15 17:05 ` Jason Gunthorpe
2022-03-15 21:24 ` Jacob Pan
2022-03-16 10:32 ` Tian, Kevin
2022-03-16 8:41 ` Tian, Kevin
2022-03-16 14:07 ` Jason Gunthorpe [this message]
2022-03-15 14:35 ` Jason Gunthorpe
2022-03-15 16:38 ` Jacob Pan
2022-03-15 23:05 ` Jason Gunthorpe
2022-03-18 12:43 ` Lu Baolu
2022-03-28 21:44 ` Jacob Pan
2022-03-15 5:07 ` [PATCH v2 6/8] dmaengine: idxd: Use DMA API for in-kernel DMA with PASID Jacob Pan
2022-03-18 6:10 ` Tian, Kevin
2022-03-29 17:39 ` Jacob Pan
2022-03-15 5:07 ` [PATCH v2 7/8] iommu/vt-d: Delete supervisor/kernel SVA Jacob Pan
2022-03-18 6:16 ` Tian, Kevin
2022-03-29 17:42 ` Jacob Pan
2022-03-15 5:07 ` [PATCH v2 8/8] iommu: Remove unused driver data in sva_bind_device Jacob Pan
2022-03-15 11:37 ` Jean-Philippe Brucker
2022-03-15 5:07 ` [PATCH v2 9/9] dmaengine: idxd: separate user and kernel pasid enabling Jacob Pan
2022-03-18 6:28 ` Tian, Kevin
2022-03-15 8:16 ` [PATCH v2 0/8] Enable PASID for DMA API users Tian, Kevin
2022-03-15 15:49 ` Jacob Pan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220316140748.GF11336@nvidia.com \
--to=jgg@nvidia.com \
--cc=ashok.raj@intel.com \
--cc=baolu.lu@linux.intel.com \
--cc=dan.j.williams@intel.com \
--cc=dave.jiang@intel.com \
--cc=hch@infradead.org \
--cc=iommu@lists.linux-foundation.org \
--cc=jacob.jun.pan@intel.com \
--cc=jacob.jun.pan@linux.intel.com \
--cc=jean-philippe@linaro.com \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=robin.murphy@arm.com \
--cc=sanjay.k.kumar@intel.com \
--cc=tom.zanussi@intel.com \
--cc=tony.luck@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox