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From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
	iommu@lists.linux-foundation.org,
	LKML <linux-kernel@vger.kernel.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Jonathan Cameron <jic23@kernel.org>
Subject: Re: [PATCH 4/4] iommu: Introduce guest PASID bind function
Date: Fri, 20 Sep 2019 18:38:43 +0200	[thread overview]
Message-ID: <20190920163843.GD1533866@lophozonia> (raw)
In-Reply-To: <1568849194-47874-5-git-send-email-jacob.jun.pan@linux.intel.com>

On Wed, Sep 18, 2019 at 04:26:34PM -0700, Jacob Pan wrote:
> Guest shared virtual address (SVA) may require host to shadow guest
> PASID tables. Guest PASID can also be allocated from the host via
> enlightened interfaces. In this case, guest needs to bind the guest
> mm, i.e. cr3 in guest physical address to the actual PASID table in
> the host IOMMU. Nesting will be turned on such that guest virtual
> address can go through a two level translation:
> - 1st level translates GVA to GPA
> - 2nd level translates GPA to HPA
> This patch introduces APIs to bind guest PASID data to the assigned
> device entry in the physical IOMMU. See the diagram below for usage
> explaination.

explanation

Otherwise Looks fine to me. I was wondering if we would be able to reuse
the API for Arm SMMUv2, which allows nesting translation, but without
PASID - there is a single address space per device, with two stages of
translation. I think it would work, although it would look better with
something like "PGD" instead of "PASID" in the API names (e.g.
iommu_sva_bind_gpgd) since that case wouldn't use PASID at all. But I
don't want to quibble over names, so

Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
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      reply	other threads:[~2019-09-20 16:38 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-18 23:26 [PATCH 0/4] User API for nested shared virtual address (SVA) Jacob Pan
2019-09-18 23:26 ` [PATCH 1/4] iommu: Introduce cache_invalidate API Jacob Pan
2019-09-20 16:32   ` Jean-Philippe Brucker
2019-09-18 23:26 ` [PATCH 2/4] iommu: Add I/O ASID allocator Jacob Pan
2019-09-19  6:30   ` kbuild test robot
2019-09-20 16:33   ` Jean-Philippe Brucker
2019-09-18 23:26 ` [PATCH 3/4] iommu/ioasid: Add custom allocators Jacob Pan
2019-09-20 16:35   ` Jean-Philippe Brucker
2019-09-21 17:42     ` Jacob Pan
2019-09-18 23:26 ` [PATCH 4/4] iommu: Introduce guest PASID bind function Jacob Pan
2019-09-20 16:38   ` Jean-Philippe Brucker [this message]

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