Re: [PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support - Jean-Philippe Brucker

From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Ashok Raj <ashok.raj@intel.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Christoph Hellwig <hch@infradead.org>,
	Vinod Koul <vkoul@kernel.org>,
	Jacob jun Pan <jacob.jun.pan@intel.com>,
	Jason Gunthorpe <jgg@nvidia.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support
Date: Wed, 25 May 2022 12:06:43 +0100	[thread overview]
Message-ID: <Yo4Nw9QyllT1RZbd@myrica> (raw)
In-Reply-To: <567dffd4-8f15-ffb2-da69-4f47017c35fd@arm.com>

On Wed, May 25, 2022 at 11:07:49AM +0100, Robin Murphy wrote:
> > Did you mean @handler and @handler_token staffs below?
> > 
> > struct iommu_domain {
> >          unsigned type;
> >          const struct iommu_domain_ops *ops;
> >          unsigned long pgsize_bitmap;    /* Bitmap of page sizes in use */
> >          iommu_fault_handler_t handler;
> >          void *handler_token;
> >          struct iommu_domain_geometry geometry;
> >          struct iommu_dma_cookie *iova_cookie;
> > };
> > 
> > Is it only for DMA domains? From the point view of IOMMU faults, it
> > seems to be generic.
> 
> Yes, it's the old common iommu_set_fault_handler() stuff (which arguably is
> more of a "notifier" than a "handler"), but I assume that that's irrelevant
> if SVA is using IOPF instead?

Yes IOMMU drivers call either the newer iommu_report_device_fault() or the
old report_iommu_fault(), and only the former can support IOPF/SVA. I've
tried to merge them before but never completed it. I think the main issue
was with finding the endpoint that caused the fault from the fault
handler. Some IOMMU drivers just pass the IOMMU device to
report_iommu_fault(). I'll probably pick that up at some point.

Thanks,
Jean
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