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

[Jordan Crouse <jcrouse@codeaurora.org>]

On Thu, Feb 11, 2021 at 06:50:28PM +0530, Akhil P Oommen wrote:
> 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@codeaurora.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.

I thought about it and I think I want to force an accept list here instead of
letting new targets get by with an implicit pass.

Jordan

> -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,
> >
> 

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