linux-kernel - Re: [PATCH 0/2] iommu/amd: Fix IOMMUv2 devices when SME is active

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Date:   Mon, 7 Sep 2020 12:44:32 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     "Deucher, Alexander" <Alexander.Deucher@....com>
Cc:     "jroedel@...e.de" <jroedel@...e.de>,
        "Kuehling, Felix" <Felix.Kuehling@....com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "Huang, Ray" <Ray.Huang@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] iommu/amd: Fix IOMMUv2 devices when SME is active

On Sun, Sep 06, 2020 at 04:08:58PM +0000, Deucher, Alexander wrote:
> From f479b9da353c2547c26ebac8930a5dcd9a134eb7 Mon Sep 17 00:00:00 2001
> From: Alex Deucher <alexander.deucher@....com>
> Date: Sun, 6 Sep 2020 12:05:12 -0400
> Subject: [PATCH] drm/amdgpu: Fail to load on RAVEN if SME is active
> 
> Due to hardware bugs, scatter/gather display on raven requires
> a 1:1 IOMMU mapping, however, SME (System Memory Encryption)
> requires an indirect IOMMU mapping because the encryption bit
> is beyond the DMA mask of the chip.  As such, the two are
> incompatible.
> 
> Signed-off-by: Alex Deucher <alexander.deucher@....com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 12e16445df7c..d87d37c25329 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -1102,6 +1102,16 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
>  		return -ENODEV;
>  	}
>  
> +	/* Due to hardware bugs, S/G Display on raven requires a 1:1 IOMMU mapping,
> +	 * however, SME requires an indirect IOMMU mapping because the encryption
> +	 * bit is beyond the DMA mask of the chip.
> +	 */
> +	if (mem_encrypt_active() && ((flags & AMD_ASIC_MASK) == CHIP_RAVEN)) {
> +		dev_info(&pdev->dev,
> +			 "SME is not compatible with RAVEN\n");
> +		return -ENOTSUPP;
> +	}
> +
>  #ifdef CONFIG_DRM_AMDGPU_SI
>  	if (!amdgpu_si_support) {
>  		switch (flags & AMD_ASIC_MASK) {
> -- 
> 2.25.4
>

Looks good to me, thanks.

Acked-by: Joerg Roedel <jroedel@...e.de>