From: "Luck, Tony" <tony.luck@intel.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>,
Jason Gunthorpe <jgg@nvidia.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>,
David Woodhouse <dwmw2@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"zhangfei.gao@linaro.org" <zhangfei.gao@linaro.org>,
Jean-Philippe Brucker <jean-philippe@linaro.com>
Subject: RE: [PATCH v4 1/2] iommu/sva: Tighten SVA bind API with explicit flags
Date: Thu, 13 May 2021 16:44:14 +0000 [thread overview]
Message-ID: <dd52760ab65a40328b4c1a26ddd0e1d0@intel.com> (raw)
In-Reply-To: <20210513081050.5cf6a6ed@jacob-builder>
> For shared workqueue, it can only generate DMA request with PASID. The
> submission is done by ENQCMDS (S for supervisor) instruction.
>
> If we were not to share page tables with init_mm, we need a system PASID
> that doing the same direct mapping in IOMMU page tables.
Note that for the currently envisioned kernel use cases for accelerators it
would be OK for this system PASID to just provide either:
1) A 1:1 mapping for physical addresses. Kernel users of the accelerators
would provide physical addresses in descriptors.
2) The same mapping that the kernel uses for its "1:1" map of all physical
memory. Users would use kernel virtual addresses in that "1:1" range
(e.g. those obtained from page_to_virt(struct page *p);)
If people want to use an accelerator on memory allocated by vmalloc()
things will get more complicated. But maybe we can delay solving that
problem until someone comes up with a real use case that needs to
do this?
-Tony
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next prev parent reply other threads:[~2021-05-13 16:44 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 13:25 [PATCH v4 0/2] Simplify and restrict IOMMU SVA APIs Jacob Pan
2021-05-10 13:25 ` [PATCH v4 1/2] iommu/sva: Tighten SVA bind API with explicit flags Jacob Pan
2021-05-10 23:37 ` Jason Gunthorpe
2021-05-11 3:31 ` Jacob Pan
2021-05-11 11:48 ` Jason Gunthorpe
2021-05-11 16:14 ` Jacob Pan
2021-05-11 16:35 ` Jason Gunthorpe
2021-05-11 18:05 ` Jacob Pan
2021-05-11 19:47 ` Jason Gunthorpe
2021-05-12 6:37 ` Christoph Hellwig
2021-05-13 13:00 ` Jacob Pan
2021-05-13 13:38 ` Jason Gunthorpe
2021-05-13 15:10 ` Jacob Pan
2021-05-13 16:44 ` Luck, Tony [this message]
2021-05-13 17:33 ` Jason Gunthorpe
2021-05-13 18:53 ` Luck, Tony
2021-05-13 19:00 ` Jason Gunthorpe
2021-05-13 19:14 ` Luck, Tony
2021-05-13 19:20 ` Jason Gunthorpe
2021-05-13 19:46 ` Jacob Pan
2021-05-13 19:57 ` Luck, Tony
2021-05-13 20:22 ` Jacob Pan
2021-05-13 22:31 ` Jason Gunthorpe
2021-05-13 23:40 ` Jacob Pan
2021-05-17 14:37 ` Jason Gunthorpe
2021-05-19 15:46 ` Jacob Pan
2021-05-12 10:18 ` Jean-Philippe Brucker
2021-05-10 13:25 ` [PATCH v4 2/2] iommu/sva: Remove mm parameter from SVA bind API Jacob Pan
2021-05-12 10:24 ` Jean-Philippe Brucker
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