linux-kernel - Re: [Freedreno] [PATCH v2 6/6] drm/msm/a6xx: Add support for per-instance pagetables

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Message-ID: <20200629145650.GC25740@jcrouse1-lnx.qualcomm.com>
Date:   Mon, 29 Jun 2020 08:56:50 -0600
From:   Jordan Crouse <jcrouse@...eaurora.org>
To:     Rob Clark <robdclark@...il.com>
Cc:     Sean Paul <sean@...rly.run>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        David Airlie <airlied@...ux.ie>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Sharat Masetty <smasetty@...eaurora.org>,
        Akhil P Oommen <akhilpo@...eaurora.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Eric Anholt <eric@...olt.net>,
        "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg
        Roedel <joro@...tes.org>, " <iommu@...ts.linux-foundation.org>,
        John Stultz <john.stultz@...aro.org>,
        Daniel Vetter <daniel@...ll.ch>,
        freedreno <freedreno@...ts.freedesktop.org>,
        Emil Velikov <emil.velikov@...labora.com>
Subject: Re: [Freedreno] [PATCH v2 6/6] drm/msm/a6xx: Add support for
 per-instance pagetables

On Sat, Jun 27, 2020 at 01:11:14PM -0700, Rob Clark wrote:
> On Sat, Jun 27, 2020 at 12:56 PM Rob Clark <robdclark@...il.com> wrote:
> >
> > On Fri, Jun 26, 2020 at 1:04 PM Jordan Crouse <jcrouse@...eaurora.org> wrote:
> > >
> > > Add support for using per-instance pagetables if all the dependencies are
> > > available.
> > >
> > > Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
> > > ---
> > >
> > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 43 +++++++++++++++++++++++++++
> > >  drivers/gpu/drm/msm/msm_ringbuffer.h  |  1 +
> > >  2 files changed, 44 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > index aa53f47b7e8b..95ed2ceac121 100644
> > > --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > @@ -79,6 +79,34 @@ static void get_stats_counter(struct msm_ringbuffer *ring, u32 counter,
> > >         OUT_RING(ring, upper_32_bits(iova));
> > >  }
> > >
> > > +static void a6xx_set_pagetable(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
> > > +               struct msm_file_private *ctx)
> > > +{
> > > +       phys_addr_t ttbr;
> > > +       u32 asid;
> > > +
> > > +       if (msm_iommu_pagetable_params(ctx->aspace->mmu, &ttbr, &asid))
> > > +               return;
> > > +
> > > +       /* Execute the table update */
> > > +       OUT_PKT7(ring, CP_SMMU_TABLE_UPDATE, 4);
> > > +       OUT_RING(ring, lower_32_bits(ttbr));
> > > +       OUT_RING(ring, (((u64) asid) << 48) | upper_32_bits(ttbr));
> > > +       /* CONTEXTIDR is currently unused */
> > > +       OUT_RING(ring, 0);
> > > +       /* CONTEXTBANK is currently unused */
> > > +       OUT_RING(ring, 0);
> > > +
> > > +       /*
> > > +        * Write the new TTBR0 to the memstore. This is good for debugging.
> > > +        */
> > > +       OUT_PKT7(ring, CP_MEM_WRITE, 4);
> > > +       OUT_RING(ring, lower_32_bits(rbmemptr(ring, ttbr0)));
> > > +       OUT_RING(ring, upper_32_bits(rbmemptr(ring, ttbr0)));
> > > +       OUT_RING(ring, lower_32_bits(ttbr));
> > > +       OUT_RING(ring, (((u64) asid) << 48) | upper_32_bits(ttbr));
> > > +}
> > > +
> > >  static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit,
> > >         struct msm_file_private *ctx)
> > >  {
> > > @@ -89,6 +117,8 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit,
> > >         struct msm_ringbuffer *ring = submit->ring;
> > >         unsigned int i;
> > >
> > > +       a6xx_set_pagetable(gpu, ring, ctx);
> > > +
> > >         get_stats_counter(ring, REG_A6XX_RBBM_PERFCTR_CP_0_LO,
> > >                 rbmemptr_stats(ring, index, cpcycles_start));
> > >
> > > @@ -872,6 +902,18 @@ static unsigned long a6xx_gpu_busy(struct msm_gpu *gpu)
> > >         return (unsigned long)busy_time;
> > >  }
> > >
> > > +struct msm_gem_address_space *a6xx_address_space_instance(struct msm_gpu *gpu)
> > > +{
> > > +       struct msm_mmu *mmu;
> > > +
> > > +       mmu = msm_iommu_pagetable_create(gpu->aspace->mmu);
> > > +       if (IS_ERR(mmu))
> > > +               return msm_gem_address_space_get(gpu->aspace);
> > > +
> > > +       return msm_gem_address_space_create(mmu,
> > > +               "gpu", 0x100000000ULL, 0x1ffffffffULL);
> > > +}
> > > +
> > >  static const struct adreno_gpu_funcs funcs = {
> > >         .base = {
> > >                 .get_param = adreno_get_param,
> > > @@ -895,6 +937,7 @@ static const struct adreno_gpu_funcs funcs = {
> > >                 .gpu_state_put = a6xx_gpu_state_put,
> > >  #endif
> > >                 .create_address_space = adreno_iommu_create_address_space,
> > > +               .address_space_instance = a6xx_address_space_instance,
> >
> > Hmm, maybe instead of .address_space_instance, something like
> > .create_context_address_space?
> >
> > Since like .create_address_space, it is creating an address space..
> > the difference is that it is a per context/process aspace..
> >

This is a good suggestion. I'm always open to changing function names.

> 
> 
> or maybe just .create_pgtable and return the 'struct msm_mmu' (which
> is itself starting to become less of a great name)..
> 
> The only other thing a6xx_address_space_instance() adds is knowing
> where the split is between the kernel and user pgtables, and I suppose
> that isn't a thing that would really be changing between gens?

In theory the split is determined by the hardware but its been the same for all
a5xx/a6xx targets.

Jordan

> BR,
> -R
> 
> > BR,
> > -R
> >
> > >         },
> > >         .get_timestamp = a6xx_get_timestamp,
> > >  };
> > > diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
> > > index 7764373d0ed2..0987d6bf848c 100644
> > > --- a/drivers/gpu/drm/msm/msm_ringbuffer.h
> > > +++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
> > > @@ -31,6 +31,7 @@ struct msm_rbmemptrs {
> > >         volatile uint32_t fence;
> > >
> > >         volatile struct msm_gpu_submit_stats stats[MSM_GPU_SUBMIT_STATS_COUNT];
> > > +       volatile u64 ttbr0;
> > >  };
> > >
> > >  struct msm_ringbuffer {
> > > --
> > > 2.17.1
> > >
> _______________________________________________
> Freedreno mailing list
> Freedreno@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/freedreno

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