linux-kernel - Re: [Intel-gfx] [PATCH 0/8] Convert the intel iommu driver to the dma-iommu api

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Date:   Tue, 8 Sep 2020 23:43:19 +0100
From:   Tom Murphy <murphyt7@....ie>
To:     Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
Cc:     Logan Gunthorpe <logang@...tatee.com>, kvm@...r.kernel.org,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-tegra@...r.kernel.org, Julien Grall <julien.grall@....com>,
        Will Deacon <will@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        linux-samsung-soc@...r.kernel.org, Marc Zyngier <maz@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        linux-rockchip@...ts.infradead.org, Andy Gross <agross@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org,
        Matthias Brugger <matthias.bgg@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        virtualization@...ts.linux-foundation.org,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Cornelia Huck <cohuck@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        iommu@...ts.linux-foundation.org, Kukjin Kim <kgene@...nel.org>,
        Robin Murphy <robin.murphy@....com>
Subject: Re: [Intel-gfx] [PATCH 0/8] Convert the intel iommu driver to the
 dma-iommu api

On Tue, 8 Sep 2020 at 16:56, Tvrtko Ursulin
<tvrtko.ursulin@...ux.intel.com> wrote:
>
>
> On 08/09/2020 16:44, Logan Gunthorpe wrote:
> > On 2020-09-08 9:28 a.m., Tvrtko Ursulin wrote:
> >>>
> >>> diff --git a/drivers/gpu/drm/i915/i915_scatterlist.h
> >>> b/drivers/gpu/drm/i915/i915
> >>> index b7b59328cb76..9367ac801f0c 100644
> >>> --- a/drivers/gpu/drm/i915/i915_scatterlist.h
> >>> +++ b/drivers/gpu/drm/i915/i915_scatterlist.h
> >>> @@ -27,13 +27,19 @@ static __always_inline struct sgt_iter {
> >>>    } __sgt_iter(struct scatterlist *sgl, bool dma) {
> >>>           struct sgt_iter s = { .sgp = sgl };
> >>>
> >>> +       if (sgl && !sg_dma_len(s.sgp))
> >>
> >> I'd extend the condition to be, just to be safe:
> >>      if (dma && sgl && !sg_dma_len(s.sgp))
> >>
> >
> > Right, good catch, that's definitely necessary.
> >
> >>> +               s.sgp = NULL;
> >>> +
> >>>           if (s.sgp) {
> >>>                   s.max = s.curr = s.sgp->offset;
> >>> -               s.max += s.sgp->length;
> >>> -               if (dma)
> >>> +
> >>> +               if (dma) {
> >>> +                       s.max += sg_dma_len(s.sgp);
> >>>                           s.dma = sg_dma_address(s.sgp);
> >>> -               else
> >>> +               } else {
> >>> +                       s.max += s.sgp->length;
> >>>                           s.pfn = page_to_pfn(sg_page(s.sgp));
> >>> +               }
> >>
> >> Otherwise has this been tested or alternatively how to test it? (How to
> >> repro the issue.)
> >
> > It has not been tested. To test it, you need Tom's patch set without the
> > last "DO NOT MERGE" patch:
> >
> > https://lkml.kernel.org/lkml/20200907070035.GA25114@infradead.org/T/
>
> Tom, do you have a branch somewhere I could pull from? (Just being lazy
> about downloading a bunch of messages from the archives.)

I don't unfortunately. I'm working locally with poor internet.

>
> What GPU is in your Lenovo x1 carbon 5th generation and what
> graphical/desktop setup I need to repro?


Is this enough info?:

$ lspci -vnn | grep VGA -A 12
00:02.0 VGA compatible controller [0300]: Intel Corporation HD
Graphics 620 [8086:5916] (rev 02) (prog-if 00 [VGA controller])
    Subsystem: Lenovo ThinkPad X1 Carbon 5th Gen [17aa:224f]
    Flags: bus master, fast devsel, latency 0, IRQ 148
    Memory at eb000000 (64-bit, non-prefetchable) [size=16M]
    Memory at 60000000 (64-bit, prefetchable) [size=256M]
    I/O ports at e000 [size=64]
    [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
    Capabilities: [40] Vendor Specific Information: Len=0c <?>
    Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
    Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
    Capabilities: [d0] Power Management version 2
    Capabilities: [100] Process Address Space ID (PASID)
    Capabilities: [200] Address Translation Service (ATS)


>
> Regards,
>
> Tvrtko