Re: [PATCH v5 5/5] drm/msm: devcoredump iommu fault support

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On Thu, Jun 10, 2021 at 02:44:13PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
> 
> Wire up support to stall the SMMU on iova fault, and collect a devcore-
> dump snapshot for easier debugging of faults.
> 
> Currently this is a6xx-only, but mostly only because so far it is the
> only one using adreno-smmu-priv.

Acked-by: Jordan Crouse <jordan@xxxxxxxxxxxxxxxxx>
 
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c       | 19 +++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c       | 38 +++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c | 42 ++++++++++++++----
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c     | 15 +++++++
>  drivers/gpu/drm/msm/msm_gem.h               |  1 +
>  drivers/gpu/drm/msm/msm_gem_submit.c        |  1 +
>  drivers/gpu/drm/msm/msm_gpu.c               | 48 +++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_gpu.h               | 17 ++++++++
>  drivers/gpu/drm/msm/msm_gpummu.c            |  5 +++
>  drivers/gpu/drm/msm/msm_iommu.c             | 11 +++++
>  drivers/gpu/drm/msm/msm_mmu.h               |  1 +
>  11 files changed, 186 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> index eb030b00bff4..7a271de9a212 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> @@ -1200,6 +1200,15 @@ static void a5xx_fault_detect_irq(struct msm_gpu *gpu)
>  	struct drm_device *dev = gpu->dev;
>  	struct msm_ringbuffer *ring = gpu->funcs->active_ring(gpu);
>  
> +	/*
> +	 * If stalled on SMMU fault, we could trip the GPU's hang detection,
> +	 * but the fault handler will trigger the devcore dump, and we want
> +	 * to otherwise resume normally rather than killing the submit, so
> +	 * just bail.
> +	 */
> +	if (gpu_read(gpu, REG_A5XX_RBBM_STATUS3) & BIT(24))
> +		return;
> +
>  	DRM_DEV_ERROR(dev->dev, "gpu fault ring %d fence %x status %8.8X rb %4.4x/%4.4x ib1 %16.16llX/%4.4x ib2 %16.16llX/%4.4x\n",
>  		ring ? ring->id : -1, ring ? ring->seqno : 0,
>  		gpu_read(gpu, REG_A5XX_RBBM_STATUS),
> @@ -1523,6 +1532,7 @@ static struct msm_gpu_state *a5xx_gpu_state_get(struct msm_gpu *gpu)
>  {
>  	struct a5xx_gpu_state *a5xx_state = kzalloc(sizeof(*a5xx_state),
>  			GFP_KERNEL);
> +	bool stalled = !!(gpu_read(gpu, REG_A5XX_RBBM_STATUS3) & BIT(24));
>  
>  	if (!a5xx_state)
>  		return ERR_PTR(-ENOMEM);
> @@ -1535,8 +1545,13 @@ static struct msm_gpu_state *a5xx_gpu_state_get(struct msm_gpu *gpu)
>  
>  	a5xx_state->base.rbbm_status = gpu_read(gpu, REG_A5XX_RBBM_STATUS);
>  
> -	/* Get the HLSQ regs with the help of the crashdumper */
> -	a5xx_gpu_state_get_hlsq_regs(gpu, a5xx_state);
> +	/*
> +	 * Get the HLSQ regs with the help of the crashdumper, but only if
> +	 * we are not stalled in an iommu fault (in which case the crashdumper
> +	 * would not have access to memory)
> +	 */
> +	if (!stalled)
> +		a5xx_gpu_state_get_hlsq_regs(gpu, a5xx_state);
>  
>  	a5xx_set_hwcg(gpu, true);
>  
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index fc19db10bff1..c3699408bd1f 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -1081,6 +1081,16 @@ static int a6xx_fault_handler(void *arg, unsigned long iova, int flags, void *da
>  	struct msm_gpu *gpu = arg;
>  	struct adreno_smmu_fault_info *info = data;
>  	const char *type = "UNKNOWN";
> +	const char *block;
> +	bool do_devcoredump = info && !READ_ONCE(gpu->crashstate);
> +
> +	/*
> +	 * If we aren't going to be resuming later from fault_worker, then do
> +	 * it now.
> +	 */
> +	if (!do_devcoredump) {
> +		gpu->aspace->mmu->funcs->resume_translation(gpu->aspace->mmu);
> +	}
>  
>  	/*
>  	 * Print a default message if we couldn't get the data from the
> @@ -1104,15 +1114,30 @@ static int a6xx_fault_handler(void *arg, unsigned long iova, int flags, void *da
>  	else if (info->fsr & ARM_SMMU_FSR_EF)
>  		type = "EXTERNAL";
>  
> +	block = a6xx_fault_block(gpu, info->fsynr1 & 0xff);
> +
>  	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),
> +			flags & IOMMU_FAULT_WRITE ? "WRITE" : "READ",
> +			type, block,
>  			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)));
>  
> +	if (do_devcoredump) {
> +		/* Turn off the hangcheck timer to keep it from bothering us */
> +		del_timer(&gpu->hangcheck_timer);
> +
> +		gpu->fault_info.ttbr0 = info->ttbr0;
> +		gpu->fault_info.iova  = iova;
> +		gpu->fault_info.flags = flags;
> +		gpu->fault_info.type  = type;
> +		gpu->fault_info.block = block;
> +
> +		kthread_queue_work(gpu->worker, &gpu->fault_work);
> +	}
> +
>  	return 0;
>  }
>  
> @@ -1164,6 +1189,15 @@ static void a6xx_fault_detect_irq(struct msm_gpu *gpu)
>  	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
>  	struct msm_ringbuffer *ring = gpu->funcs->active_ring(gpu);
>  
> +	/*
> +	 * If stalled on SMMU fault, we could trip the GPU's hang detection,
> +	 * but the fault handler will trigger the devcore dump, and we want
> +	 * to otherwise resume normally rather than killing the submit, so
> +	 * just bail.
> +	 */
> +	if (gpu_read(gpu, REG_A6XX_RBBM_STATUS3) & A6XX_RBBM_STATUS3_SMMU_STALLED_ON_FAULT)
> +		return;
> +
>  	/*
>  	 * Force the GPU to stay on until after we finish
>  	 * collecting information
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
> index 21c49c5b4519..ad4ea0ed5d99 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
> @@ -832,6 +832,20 @@ static void a6xx_get_registers(struct msm_gpu *gpu,
>  		a6xx_get_ahb_gpu_registers(gpu,
>  				a6xx_state, &a6xx_vbif_reglist,
>  				&a6xx_state->registers[index++]);
> +	if (!dumper) {
> +		/*
> +		 * We can't use the crashdumper when the SMMU is stalled,
> +		 * because the GPU has no memory access until we resume
> +		 * translation (but we don't want to do that until after
> +		 * we have captured as much useful GPU state as possible).
> +		 * So instead collect registers via the CPU:
> +		 */
> +		for (i = 0; i < ARRAY_SIZE(a6xx_reglist); i++)
> +			a6xx_get_ahb_gpu_registers(gpu,
> +				a6xx_state, &a6xx_reglist[i],
> +				&a6xx_state->registers[index++]);
> +		return;
> +	}
>  
>  	for (i = 0; i < ARRAY_SIZE(a6xx_reglist); i++)
>  		a6xx_get_crashdumper_registers(gpu,
> @@ -905,11 +919,13 @@ static void a6xx_get_indexed_registers(struct msm_gpu *gpu,
>  
>  struct msm_gpu_state *a6xx_gpu_state_get(struct msm_gpu *gpu)
>  {
> -	struct a6xx_crashdumper dumper = { 0 };
> +	struct a6xx_crashdumper _dumper = { 0 }, *dumper = NULL;
>  	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
>  	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
>  	struct a6xx_gpu_state *a6xx_state = kzalloc(sizeof(*a6xx_state),
>  		GFP_KERNEL);
> +	bool stalled = !!(gpu_read(gpu, REG_A6XX_RBBM_STATUS3) &
> +			A6XX_RBBM_STATUS3_SMMU_STALLED_ON_FAULT);
>  
>  	if (!a6xx_state)
>  		return ERR_PTR(-ENOMEM);
> @@ -928,14 +944,24 @@ struct msm_gpu_state *a6xx_gpu_state_get(struct msm_gpu *gpu)
>  	/* Get the banks of indexed registers */
>  	a6xx_get_indexed_registers(gpu, a6xx_state);
>  
> -	/* Try to initialize the crashdumper */
> -	if (!a6xx_crashdumper_init(gpu, &dumper)) {
> -		a6xx_get_registers(gpu, a6xx_state, &dumper);
> -		a6xx_get_shaders(gpu, a6xx_state, &dumper);
> -		a6xx_get_clusters(gpu, a6xx_state, &dumper);
> -		a6xx_get_dbgahb_clusters(gpu, a6xx_state, &dumper);
> +	/*
> +	 * Try to initialize the crashdumper, if we are not dumping state
> +	 * with the SMMU stalled.  The crashdumper needs memory access to
> +	 * write out GPU state, so we need to skip this when the SMMU is
> +	 * stalled in response to an iova fault
> +	 */
> +	if (!stalled && !a6xx_crashdumper_init(gpu, &_dumper)) {
> +		dumper = &_dumper;
> +	}
> +
> +	a6xx_get_registers(gpu, a6xx_state, dumper);
> +
> +	if (dumper) {
> +		a6xx_get_shaders(gpu, a6xx_state, dumper);
> +		a6xx_get_clusters(gpu, a6xx_state, dumper);
> +		a6xx_get_dbgahb_clusters(gpu, a6xx_state, dumper);
>  
> -		msm_gem_kernel_put(dumper.bo, gpu->aspace, true);
> +		msm_gem_kernel_put(dumper->bo, gpu->aspace, true);
>  	}
>  
>  	if (snapshot_debugbus)
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index c1b02f790804..2bfe014995c7 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -684,6 +684,21 @@ void adreno_show(struct msm_gpu *gpu, struct msm_gpu_state *state,
>  			adreno_gpu->info->revn, adreno_gpu->rev.core,
>  			adreno_gpu->rev.major, adreno_gpu->rev.minor,
>  			adreno_gpu->rev.patchid);
> +	/*
> +	 * If this is state collected due to iova fault, so fault related info
> +	 *
> +	 * TTBR0 would not be zero, so this is a good way to distinguish
> +	 */
> +	if (state->fault_info.ttbr0) {
> +		const struct msm_gpu_fault_info *info = &state->fault_info;
> +
> +		drm_puts(p, "fault-info:\n");
> +		drm_printf(p, "  - ttbr0=%.16llx\n", info->ttbr0);
> +		drm_printf(p, "  - iova=%.16lx\n", info->iova);
> +		drm_printf(p, "  - dir=%s\n", info->flags & IOMMU_FAULT_WRITE ? "WRITE" : "READ");
> +		drm_printf(p, "  - type=%s\n", info->type);
> +		drm_printf(p, "  - source=%s\n", info->block);
> +	}
>  
>  	drm_printf(p, "rbbm-status: 0x%08x\n", state->rbbm_status);
>  
> diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
> index 03e2cc2a2ce1..405f8411e395 100644
> --- a/drivers/gpu/drm/msm/msm_gem.h
> +++ b/drivers/gpu/drm/msm/msm_gem.h
> @@ -328,6 +328,7 @@ struct msm_gem_submit {
>  	struct dma_fence *fence;
>  	struct msm_gpu_submitqueue *queue;
>  	struct pid *pid;    /* submitting process */
> +	bool fault_dumped;  /* Limit devcoredump dumping to one per submit */
>  	bool valid;         /* true if no cmdstream patching needed */
>  	bool in_rb;         /* "sudo" mode, copy cmds into RB */
>  	struct msm_ringbuffer *ring;
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index 5480852bdeda..44f84bfd0c0e 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -50,6 +50,7 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,
>  	submit->cmd = (void *)&submit->bos[nr_bos];
>  	submit->queue = queue;
>  	submit->ring = gpu->rb[queue->prio];
> +	submit->fault_dumped = false;
>  
>  	/* initially, until copy_from_user() and bo lookup succeeds: */
>  	submit->nr_bos = 0;
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index fa7691cb4614..414ba2dd34e5 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -400,6 +400,7 @@ static void msm_gpu_crashstate_capture(struct msm_gpu *gpu,
>  	/* Fill in the additional crash state information */
>  	state->comm = kstrdup(comm, GFP_KERNEL);
>  	state->cmd = kstrdup(cmd, GFP_KERNEL);
> +	state->fault_info = gpu->fault_info;
>  
>  	if (submit) {
>  		int i, nr = 0;
> @@ -572,6 +573,52 @@ static void recover_worker(struct kthread_work *work)
>  	msm_gpu_retire(gpu);
>  }
>  
> +static void fault_worker(struct kthread_work *work)
> +{
> +	struct msm_gpu *gpu = container_of(work, struct msm_gpu, fault_work);
> +	struct drm_device *dev = gpu->dev;
> +	struct msm_gem_submit *submit;
> +	struct msm_ringbuffer *cur_ring = gpu->funcs->active_ring(gpu);
> +	char *comm = NULL, *cmd = NULL;
> +
> +	mutex_lock(&dev->struct_mutex);
> +
> +	submit = find_submit(cur_ring, cur_ring->memptrs->fence + 1);
> +	if (submit && submit->fault_dumped)
> +		goto resume_smmu;
> +
> +	if (submit) {
> +		struct task_struct *task;
> +
> +		task = get_pid_task(submit->pid, PIDTYPE_PID);
> +		if (task) {
> +			comm = kstrdup(task->comm, GFP_KERNEL);
> +			cmd = kstrdup_quotable_cmdline(task, GFP_KERNEL);
> +			put_task_struct(task);
> +		}
> +
> +		/*
> +		 * When we get GPU iova faults, we can get 1000s of them,
> +		 * but we really only want to log the first one.
> +		 */
> +		submit->fault_dumped = true;
> +	}
> +
> +	/* Record the crash state */
> +	pm_runtime_get_sync(&gpu->pdev->dev);
> +	msm_gpu_crashstate_capture(gpu, submit, comm, cmd);
> +	pm_runtime_put_sync(&gpu->pdev->dev);
> +
> +	kfree(cmd);
> +	kfree(comm);
> +
> +resume_smmu:
> +	memset(&gpu->fault_info, 0, sizeof(gpu->fault_info));
> +	gpu->aspace->mmu->funcs->resume_translation(gpu->aspace->mmu);
> +
> +	mutex_unlock(&dev->struct_mutex);
> +}
> +
>  static void hangcheck_timer_reset(struct msm_gpu *gpu)
>  {
>  	mod_timer(&gpu->hangcheck_timer,
> @@ -948,6 +995,7 @@ int msm_gpu_init(struct drm_device *drm, struct platform_device *pdev,
>  	INIT_LIST_HEAD(&gpu->active_list);
>  	kthread_init_work(&gpu->retire_work, retire_worker);
>  	kthread_init_work(&gpu->recover_work, recover_worker);
> +	kthread_init_work(&gpu->fault_work, fault_worker);
>  
>  	timer_setup(&gpu->hangcheck_timer, hangcheck_handler, 0);
>  
> diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> index 7a082a12d98f..8eefb3aeca10 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.h
> +++ b/drivers/gpu/drm/msm/msm_gpu.h
> @@ -71,6 +71,15 @@ struct msm_gpu_funcs {
>  	uint32_t (*get_rptr)(struct msm_gpu *gpu, struct msm_ringbuffer *ring);
>  };
>  
> +/* Additional state for iommu faults: */
> +struct msm_gpu_fault_info {
> +	u64 ttbr0;
> +	unsigned long iova;
> +	int flags;
> +	const char *type;
> +	const char *block;
> +};
> +
>  struct msm_gpu {
>  	const char *name;
>  	struct drm_device *dev;
> @@ -135,6 +144,12 @@ struct msm_gpu {
>  #define DRM_MSM_HANGCHECK_JIFFIES msecs_to_jiffies(DRM_MSM_HANGCHECK_PERIOD)
>  	struct timer_list hangcheck_timer;
>  
> +	/* Fault info for most recent iova fault: */
> +	struct msm_gpu_fault_info fault_info;
> +
> +	/* work for handling GPU ioval faults: */
> +	struct kthread_work fault_work;
> +
>  	/* work for handling GPU recovery: */
>  	struct kthread_work recover_work;
>  
> @@ -243,6 +258,8 @@ struct msm_gpu_state {
>  	char *comm;
>  	char *cmd;
>  
> +	struct msm_gpu_fault_info fault_info;
> +
>  	int nr_bos;
>  	struct msm_gpu_state_bo *bos;
>  };
> diff --git a/drivers/gpu/drm/msm/msm_gpummu.c b/drivers/gpu/drm/msm/msm_gpummu.c
> index 379496186c7f..f7d1945e0c9f 100644
> --- a/drivers/gpu/drm/msm/msm_gpummu.c
> +++ b/drivers/gpu/drm/msm/msm_gpummu.c
> @@ -68,6 +68,10 @@ static int msm_gpummu_unmap(struct msm_mmu *mmu, uint64_t iova, size_t len)
>  	return 0;
>  }
>  
> +static void msm_gpummu_resume_translation(struct msm_mmu *mmu)
> +{
> +}
> +
>  static void msm_gpummu_destroy(struct msm_mmu *mmu)
>  {
>  	struct msm_gpummu *gpummu = to_msm_gpummu(mmu);
> @@ -83,6 +87,7 @@ static const struct msm_mmu_funcs funcs = {
>  		.map = msm_gpummu_map,
>  		.unmap = msm_gpummu_unmap,
>  		.destroy = msm_gpummu_destroy,
> +		.resume_translation = msm_gpummu_resume_translation,
>  };
>  
>  struct msm_mmu *msm_gpummu_new(struct device *dev, struct msm_gpu *gpu)
> diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
> index 6975b95c3c29..eed2a762e9dd 100644
> --- a/drivers/gpu/drm/msm/msm_iommu.c
> +++ b/drivers/gpu/drm/msm/msm_iommu.c
> @@ -184,6 +184,9 @@ struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent)
>  	 * the arm-smmu driver as a trigger to set up TTBR0
>  	 */
>  	if (atomic_inc_return(&iommu->pagetables) == 1) {
> +		/* Enable stall on iommu fault: */
> +		adreno_smmu->set_stall(adreno_smmu->cookie, true);
> +
>  		ret = adreno_smmu->set_ttbr0_cfg(adreno_smmu->cookie, &ttbr0_cfg);
>  		if (ret) {
>  			free_io_pgtable_ops(pagetable->pgtbl_ops);
> @@ -226,6 +229,13 @@ static int msm_fault_handler(struct iommu_domain *domain, struct device *dev,
>  	return 0;
>  }
>  
> +static void msm_iommu_resume_translation(struct msm_mmu *mmu)
> +{
> +	struct adreno_smmu_priv *adreno_smmu = dev_get_drvdata(mmu->dev);
> +
> +	adreno_smmu->resume_translation(adreno_smmu->cookie, true);
> +}
> +
>  static void msm_iommu_detach(struct msm_mmu *mmu)
>  {
>  	struct msm_iommu *iommu = to_msm_iommu(mmu);
> @@ -273,6 +283,7 @@ static const struct msm_mmu_funcs funcs = {
>  		.map = msm_iommu_map,
>  		.unmap = msm_iommu_unmap,
>  		.destroy = msm_iommu_destroy,
> +		.resume_translation = msm_iommu_resume_translation,
>  };
>  
>  struct msm_mmu *msm_iommu_new(struct device *dev, struct iommu_domain *domain)
> diff --git a/drivers/gpu/drm/msm/msm_mmu.h b/drivers/gpu/drm/msm/msm_mmu.h
> index a88f44c3268d..de158e1bf765 100644
> --- a/drivers/gpu/drm/msm/msm_mmu.h
> +++ b/drivers/gpu/drm/msm/msm_mmu.h
> @@ -15,6 +15,7 @@ struct msm_mmu_funcs {
>  			size_t len, int prot);
>  	int (*unmap)(struct msm_mmu *mmu, uint64_t iova, size_t len);
>  	void (*destroy)(struct msm_mmu *mmu);
> +	void (*resume_translation)(struct msm_mmu *mmu);
>  };
>  
>  enum msm_mmu_type {
> -- 
> 2.31.1
> 



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