linux-kernel - Re: [PATCH v2] drm/msm: a6xx: Make sure the SQE microcode is safe

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Date:   Thu, 11 Feb 2021 18:50:28 +0530
From:   Akhil P Oommen <akhilpo@...eaurora.org>
To:     Jordan Crouse <jcrouse@...eaurora.org>,
        linux-arm-msm@...r.kernel.org
Cc:     Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...ux.ie>,
        Eric Anholt <eric@...olt.net>,
        Jonathan Marek <jonathan@...ek.ca>,
        Rob Clark <robdclark@...il.com>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Sean Paul <sean@...rly.run>,
        Sharat Masetty <smasetty@...eaurora.org>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/msm: a6xx: Make sure the SQE microcode is safe

On 2/10/2021 6:22 AM, Jordan Crouse wrote:
> Most a6xx targets have security issues that were fixed with new versions
> of the microcode(s). Make sure that we are booting with a safe version of
> the microcode for the target and print a message and error if not.
> 
> v2: Add more informative error messages and fix typos
> 
> Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
> ---
> 
>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 77 ++++++++++++++++++++++-----
>   1 file changed, 64 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index ba8e9d3cf0fe..064b7face504 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -522,28 +522,73 @@ static int a6xx_cp_init(struct msm_gpu *gpu)
>   	return a6xx_idle(gpu, ring) ? 0 : -EINVAL;
>   }
>   
> -static void a6xx_ucode_check_version(struct a6xx_gpu *a6xx_gpu,
> +/*
> + * Check that the microcode version is new enough to include several key
> + * security fixes. Return true if the ucode is safe.
> + */
> +static bool a6xx_ucode_check_version(struct a6xx_gpu *a6xx_gpu,
>   		struct drm_gem_object *obj)
>   {
> +	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
> +	struct msm_gpu *gpu = &adreno_gpu->base;
>   	u32 *buf = msm_gem_get_vaddr(obj);
> +	bool ret = false;
>   
>   	if (IS_ERR(buf))
> -		return;
> +		return false;
>   
>   	/*
> -	 * If the lowest nibble is 0xa that is an indication that this microcode
> -	 * has been patched. The actual version is in dword [3] but we only care
> -	 * about the patchlevel which is the lowest nibble of dword [3]
> -	 *
> -	 * Otherwise check that the firmware is greater than or equal to 1.90
> -	 * which was the first version that had this fix built in
> +	 * Targets up to a640 (a618, a630 and a640) need to check for a
> +	 * microcode version that is patched to support the whereami opcode or
> +	 * one that is new enough to include it by default.
>   	 */
> -	if (((buf[0] & 0xf) == 0xa) && (buf[2] & 0xf) >= 1)
> -		a6xx_gpu->has_whereami = true;
> -	else if ((buf[0] & 0xfff) > 0x190)
> -		a6xx_gpu->has_whereami = true;
> +	if (adreno_is_a618(adreno_gpu) || adreno_is_a630(adreno_gpu) ||
> +		adreno_is_a640(adreno_gpu)) {
> +		/*
> +		 * If the lowest nibble is 0xa that is an indication that this
> +		 * microcode has been patched. The actual version is in dword
> +		 * [3] but we only care about the patchlevel which is the lowest
> +		 * nibble of dword [3]
> +		 *
> +		 * Otherwise check that the firmware is greater than or equal
> +		 * to 1.90 which was the first version that had this fix built
> +		 * in
> +		 */
> +		if ((((buf[0] & 0xf) == 0xa) && (buf[2] & 0xf) >= 1) ||
> +			(buf[0] & 0xfff) >= 0x190) {
> +			a6xx_gpu->has_whereami = true;
> +			ret = true;
> +			goto out;
> +		}
>   
> +		DRM_DEV_ERROR(&gpu->pdev->dev,
> +			"a630 SQE ucode is too old. Have version %x need at least %x\n",
> +			buf[0] & 0xfff, 0x190);
> +	}  else {
> +		/*
> +		 * a650 tier targets don't need whereami but still need to be
> +		 * equal to or newer than 1.95 for other security fixes
> +		 */
> +		if (adreno_is_a650(adreno_gpu)) {
> +			if ((buf[0] & 0xfff) >= 0x195) {
> +				ret = true;
> +				goto out;
> +			}
> +
> +			DRM_DEV_ERROR(&gpu->pdev->dev,
> +				"a650 SQE ucode is too old. Have version %x need at least %x\n",
> +				buf[0] & 0xfff, 0x195);
> +		}
> +
> +		/*
> +		 * When a660 is added those targets should return true here
> +		 * since those have all the critical security fixes built in
> +		 * from the start
> +		 */
Or we can just initialize 'ret' as true.

-Akhil
> +	}
> +out:
>   	msm_gem_put_vaddr(obj);
> +	return ret;
>   }
>   
>   static int a6xx_ucode_init(struct msm_gpu *gpu)
> @@ -566,7 +611,13 @@ static int a6xx_ucode_init(struct msm_gpu *gpu)
>   		}
>   
>   		msm_gem_object_set_name(a6xx_gpu->sqe_bo, "sqefw");
> -		a6xx_ucode_check_version(a6xx_gpu, a6xx_gpu->sqe_bo);
> +		if (!a6xx_ucode_check_version(a6xx_gpu, a6xx_gpu->sqe_bo)) {
> +			msm_gem_unpin_iova(a6xx_gpu->sqe_bo, gpu->aspace);
> +			drm_gem_object_put(a6xx_gpu->sqe_bo);
> +
> +			a6xx_gpu->sqe_bo = NULL;
> +			return -EPERM;
> +		}
>   	}
>   
>   	gpu_write64(gpu, REG_A6XX_CP_SQE_INSTR_BASE_LO,
>