linux-kernel - Re: [PATCH v7 03/10] iommu/sva: Add iommu_sva

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Date:   Wed, 25 May 2022 12:06:43 +0100
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Baolu Lu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Vinod Koul <vkoul@...nel.org>, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org,
        Jacob jun Pan <jacob.jun.pan@...el.com>
Subject: Re: [PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support

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