linux-kernel - Re: [PATCH 13/19] drm/msm: Set the global virtual address range from the IOMMU domain

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Message-ID: <20200901052317.GU3715@yoga>
Date:   Tue, 1 Sep 2020 00:23:17 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Rob Clark <robdclark@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, iommu@...ts.linux-foundation.org,
        linux-arm-msm@...r.kernel.org,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Will Deacon <will@...nel.org>, freedreno@...ts.freedesktop.org,
        Sibi Sankar <sibis@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel@...ts.infradead.org,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Rob Clark <robdclark@...omium.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Marek <jonathan@...ek.ca>,
        Brian Masney <masneyb@...tation.org>,
        Shawn Guo <shawn.guo@...aro.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 13/19] drm/msm: Set the global virtual address range from
 the IOMMU domain

On Thu 13 Aug 21:41 CDT 2020, Rob Clark wrote:

> From: Jordan Crouse <jcrouse@...eaurora.org>
> 
> 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).
> 

Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

> Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
> Signed-off-by: Rob Clark <robdclark@...omium.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 533a34b4cce2..34e6242c1767 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);
>  
>  	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;
> -- 
> 2.26.2
>