linux-kernel - Re: [Freedreno] [PATCH v9 6/7] drm/msm: Set the global virtual address range from the IOMMU domain

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Date:   Sat, 27 Jun 2020 10:10:14 -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>,
        David Airlie <airlied@...ux.ie>, Sean Paul <sean@...rly.run>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Takashi Iwai <tiwai@...e.de>,
        "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>,
        Shawn Guo <shawn.guo@...aro.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Brian Masney <masneyb@...tation.org>
Subject: Re: [Freedreno] [PATCH v9 6/7] drm/msm: Set the global virtual
 address range from the IOMMU domain

On Fri, Jun 26, 2020 at 1:01 PM Jordan Crouse <jcrouse@...eaurora.org> wrote:
>
> Use the aperture settings from the IOMMU domain to set up the virtual
> address range for the GPU. This allows us to transparently deal with
> IOMMU side features (like split pagetables).
>
> Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
> ---
>
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 13 +++++++++++--
>  drivers/gpu/drm/msm/msm_iommu.c         |  7 +++++++
>  2 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index 5db06b590943..3e717c1ebb7f 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -192,9 +192,18 @@ adreno_iommu_create_address_space(struct msm_gpu *gpu,
>         struct iommu_domain *iommu = iommu_domain_alloc(&platform_bus_type);
>         struct msm_mmu *mmu = msm_iommu_new(&pdev->dev, iommu);
>         struct msm_gem_address_space *aspace;
> +       u64 start, size;
>
> -       aspace = msm_gem_address_space_create(mmu, "gpu", SZ_16M,
> -               0xffffffff - SZ_16M);
> +       /*
> +        * Use the aperture start or SZ_16M, whichever is greater. This will
> +        * ensure that we align with the allocated pagetable range while still
> +        * allowing room in the lower 32 bits for GMEM and whatnot
> +        */
> +       start = max_t(u64, SZ_16M, iommu->geometry.aperture_start);
> +       size = iommu->geometry.aperture_end - start + 1;
> +
> +       aspace = msm_gem_address_space_create(mmu, "gpu",
> +               start & GENMASK(48, 0), size);

hmm, I kinda think this isn't going to play well for the 32b gpus
(pre-a5xx).. possibly we should add address space size to 'struct
adreno_info'?

Or I guess it is always going to be the same for all devices within a
generation?  So it could just be passed in to adreno_gpu_init()

Hopefully that makes things smoother if we someday had more than 48bits..

BR,
-R

>
>         if (IS_ERR(aspace) && !IS_ERR(mmu))
>                 mmu->funcs->destroy(mmu);
> diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
> index 3a381a9674c9..1b6635504069 100644
> --- a/drivers/gpu/drm/msm/msm_iommu.c
> +++ b/drivers/gpu/drm/msm/msm_iommu.c
> @@ -36,6 +36,10 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
>         struct msm_iommu *iommu = to_msm_iommu(mmu);
>         size_t ret;
>
> +       /* The arm-smmu driver expects the addresses to be sign extended */
> +       if (iova & BIT_ULL(48))
> +               iova |= GENMASK_ULL(63, 49);
> +
>         ret = iommu_map_sg(iommu->domain, iova, sgt->sgl, sgt->nents, prot);
>         WARN_ON(!ret);
>
> @@ -46,6 +50,9 @@ static int msm_iommu_unmap(struct msm_mmu *mmu, uint64_t iova, size_t len)
>  {
>         struct msm_iommu *iommu = to_msm_iommu(mmu);
>
> +       if (iova & BIT_ULL(48))
> +               iova |= GENMASK_ULL(63, 49);
> +
>         iommu_unmap(iommu->domain, iova, len);
>
>         return 0;
> --
> 2.17.1
>
> _______________________________________________
> Freedreno mailing list
> Freedreno@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/freedreno

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