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

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Date:   Sat, 27 Jun 2020 12:56:09 -0700
From:   Rob Clark <robdclark@...il.com>
To:     Jordan Crouse <jcrouse@...eaurora.org>
Cc:     linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        "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>,
        freedreno <freedreno@...ts.freedesktop.org>,
        Akhil P Oommen <akhilpo@...eaurora.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Emil Velikov <emil.velikov@...labora.com>,
        Eric Anholt <eric@...olt.net>,
        Jonathan Marek <jonathan@...ek.ca>,
        Sean Paul <sean@...rly.run>,
        Sharat Masetty <smasetty@...eaurora.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 6/6] drm/msm/a6xx: Add support for per-instance pagetables

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..

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
>