Re: [RFC PATCH v1 3/3] drm/msm: Improve the a6xx page fault handler

From: Rob Clark
Date: Mon Nov 09 2020 - 18:15:34 EST

On Mon, Nov 9, 2020 at 2:23 PM Jordan Crouse <jcrouse@xxxxxxxxxxxxxx> wrote:
>
> Use the new adreno-smmu-priv fault info function to get more SMMU
> debug registers and print the current TTBR0 to debug per-instance
> pagetables and figure out which GPU block generated the request.
>
> Signed-off-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
> ---
>
> drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 4 +-
> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 76 +++++++++++++++++++++++++--
> drivers/gpu/drm/msm/msm_iommu.c | 11 +++-
> drivers/gpu/drm/msm/msm_mmu.h | 4 +-
> 4 files changed, 87 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> index d6804a802355..ed4cb81af874 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> @@ -933,7 +933,7 @@ bool a5xx_idle(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
> return true;
> }
>
> -static int a5xx_fault_handler(void *arg, unsigned long iova, int flags)
> +static int a5xx_fault_handler(void *arg, unsigned long iova, int flags, void *data)
> {
> struct msm_gpu *gpu = arg;
> pr_warn_ratelimited("*** gpu fault: iova=%08lx, flags=%d (%u,%u,%u,%u)\n",
> @@ -943,7 +943,7 @@ static int a5xx_fault_handler(void *arg, unsigned long iova, int flags)
> gpu_read(gpu, REG_A5XX_CP_SCRATCH_REG(6)),
> gpu_read(gpu, REG_A5XX_CP_SCRATCH_REG(7)));
>
> - return -EFAULT;
> + return 0;
> }
>
> static void a5xx_cp_err_irq(struct msm_gpu *gpu)
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 948f3656c20c..ac6e8cd5cf1a 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -905,18 +905,88 @@ static void a6xx_recover(struct msm_gpu *gpu)
> msm_gpu_hw_init(gpu);
> }
>
> -static int a6xx_fault_handler(void *arg, unsigned long iova, int flags)
> +static const char *a6xx_uche_fault_block(struct msm_gpu *gpu, u32 mid)
> +{
> + static const char *uche_clients[7] = {
> + "VFD", "SP", "VSC", "VPC", "HLSQ", "PC", "LRZ",
> + };
> + u32 val;
> +
> + if (mid < 1 || mid > 3)
> + return "UNKNOWN";
> +
> + /*
> + * The source of the data depends on the mid ID read from FSYNR1.
> + * and the client ID read from the UCHE block
> + */
> + val = gpu_read(gpu, REG_A6XX_UCHE_CLIENT_PF);
> +
> + /* mid = 3 is most precise and refers to only one block per client */
> + if (mid == 3)
> + return uche_clients[val & 7];
> +
> + /* For mid=2 the source is TP or VFD except when the client id is 0 */
> + if (mid == 2)
> + return ((val & 7) == 0) ? "TP" : "TP|VFD";
> +
> + /* For mid=1 just return "UCHE" as a catchall for everything else */
> + return "UCHE";
> +}
> +
> +static const char *a6xx_fault_block(struct msm_gpu *gpu, u32 id)
> +{
> + if (id == 0)
> + return "CP";
> + else if (id == 4)
> + return "CCU";
> + else if (id == 6)
> + return "CDP Prefetch";
> +
> + return a6xx_uche_fault_block(gpu, id);
> +}
> +
> +#define ARM_SMMU_FSR_TF BIT(1)
> +#define ARM_SMMU_FSR_PF BIT(3)
> +#define ARM_SMMU_FSR_EF BIT(4)
> +
> +static int a6xx_fault_handler(void *arg, unsigned long iova, int flags, void *data)
> {
> struct msm_gpu *gpu = arg;
> + struct adreno_smmu_fault_info *info = data;
> + const char *type = "UNKNOWN";
>
> - pr_warn_ratelimited("*** gpu fault: iova=%08lx, flags=%d (%u,%u,%u,%u)\n",
> + /*
> + * Print a default message if we couldn't get the data from the
> + * adreno-smmu-priv
> + */
> + if (!info) {
> + pr_warn_ratelimited("*** gpu fault: iova=%.16lx flags=%d (%u,%u,%u,%u)\n",
> iova, flags,
> gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(4)),
> gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(5)),
> gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(6)),
> gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(7)));
>
> - return -EFAULT;
> + return 0;
> + }
> +
> + if (info->fsr & ARM_SMMU_FSR_TF)
> + type = "TRANSLATION";
> + else if (info->fsr & ARM_SMMU_FSR_PF)
> + type = "PERMISSION";
> + else if (info->fsr & ARM_SMMU_FSR_EF)
> + type = "EXTERNAL";
> +
> + pr_warn_ratelimited("*** gpu fault: ttbr0=%.16llx iova=%.16lx dir=%s type=%s source=%s (%u,%u,%u,%u)\n",
> + info->ttbr0, iova,
> + flags & IOMMU_FAULT_WRITE ? "WRITE" : "READ", type,
> + a6xx_fault_block(gpu, info->fsynr1 & 0xff),
> + gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(4)),
> + gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(5)),
> + gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(6)),
> + gpu_read(gpu, REG_A6XX_CP_SCRATCH_REG(7)));
> +
> + return 0;
> }
>
> static void a6xx_cp_hw_err_irq(struct msm_gpu *gpu)
> diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
> index 22ac7c692a81..dc04575fc323 100644
> --- a/drivers/gpu/drm/msm/msm_iommu.c
> +++ b/drivers/gpu/drm/msm/msm_iommu.c
> @@ -212,8 +212,17 @@ static int msm_fault_handler(struct iommu_domain *domain, struct device *dev,
> unsigned long iova, int flags, void *arg)
> {
> struct msm_iommu *iommu = arg;
> + struct adreno_smmu_priv *adreno_smmu = dev_get_drvdata(iommu->base.dev);
> + struct adreno_smmu_fault_info info, *ptr = NULL;
> +
> + if (adreno_smmu->cookie) {

I suppose, to better deal with whichever order drm vs iommu stuff is merged:

if (adreno_smmu->get_fault_info) {
...
}

I don't think there is a reason to have ->get_fault_info set but ->cookie unset

BR,
-R

> + adreno_smmu->get_fault_info(adreno_smmu->cookie, &info);
> + ptr = &info;
> + }
> +
> if (iommu->base.handler)
> - return iommu->base.handler(iommu->base.arg, iova, flags);
> + return iommu->base.handler(iommu->base.arg, iova, flags, ptr);
> +
> pr_warn_ratelimited("*** fault: iova=%16lx, flags=%d\n", iova, flags);
> return 0;
> }
> diff --git a/drivers/gpu/drm/msm/msm_mmu.h b/drivers/gpu/drm/msm/msm_mmu.h
> index 61ade89d9e48..a88f44c3268d 100644
> --- a/drivers/gpu/drm/msm/msm_mmu.h
> +++ b/drivers/gpu/drm/msm/msm_mmu.h
> @@ -26,7 +26,7 @@ enum msm_mmu_type {
> struct msm_mmu {
> const struct msm_mmu_funcs *funcs;
> struct device *dev;
> - int (*handler)(void *arg, unsigned long iova, int flags);
> + int (*handler)(void *arg, unsigned long iova, int flags, void *data);
> void *arg;
> enum msm_mmu_type type;
> };
> @@ -43,7 +43,7 @@ struct msm_mmu *msm_iommu_new(struct device *dev, struct iommu_domain *domain);
> struct msm_mmu *msm_gpummu_new(struct device *dev, struct msm_gpu *gpu);
>
> static inline void msm_mmu_set_fault_handler(struct msm_mmu *mmu, void *arg,
> - int (*handler)(void *arg, unsigned long iova, int flags))
> + int (*handler)(void *arg, unsigned long iova, int flags, void *data))
> {
> mmu->arg = arg;
> mmu->handler = handler;
> --
> 2.25.1
>