Re: [PATCH 1/2] drm/panfrost: Make sure MMU context lifetime is not bound to panfrost_priv

On 04/02/2020 2:35 pm, Boris Brezillon wrote:

Jobs can be in-flight when the file descriptor is closed (either because the process did not terminate properly, or because it didn't wait for all GPU jobs to be finished), and apparently panfrost_job_close() does not cancel already running jobs. Let's refcount the MMU context object so it's lifetime is no longer bound to the FD lifetime and running jobs can finish properly without generating spurious page faults.

Yup, this remedies what I've been seeing for ages, where - given a sufficiently slow GPU - merely exiting kmscube generates a pile of translation faults. With this patch applied that no longer happens (yay!), however after a few tries I did now manage to hit this:

[ 539.190908] WARNING: CPU: 0 PID: 0 at drivers/gpu/drm/panfrost/panfrost_mmu.c:200 panfrost_mmu_as_put+0x38/0x40

after which something apparently deadlocked because some weird SCMI mailbox errors and continual RCU stalls in __switch_to() followed. Those exact symptoms are probably particular to the Juno FPGA setup, but it does seem to point to the GPU getting into an unhappy state.

Robin.

Reported-by: Icecream95 ixn@keemail.me Fixes: 7282f7645d06 ("drm/panfrost: Implement per FD address spaces") Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@collabora.com

---

drivers/gpu/drm/panfrost/panfrost_device.h | 8 +- drivers/gpu/drm/panfrost/panfrost_drv.c | 50 ++----- drivers/gpu/drm/panfrost/panfrost_gem.c | 20 ++- drivers/gpu/drm/panfrost/panfrost_job.c | 4 +- drivers/gpu/drm/panfrost/panfrost_mmu.c | 158 ++++++++++++++------- drivers/gpu/drm/panfrost/panfrost_mmu.h | 5 +- 6 files changed, 135 insertions(+), 110 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h index 06713811b92c..3f19288e8375 100644 --- a/drivers/gpu/drm/panfrost/panfrost_device.h +++ b/drivers/gpu/drm/panfrost/panfrost_device.h @@ -94,8 +94,12 @@ struct panfrost_device { }; struct panfrost_mmu {

• struct panfrost_device *pfdev;
• struct kref refcount; struct io_pgtable_cfg pgtbl_cfg; struct io_pgtable_ops *pgtbl_ops;
• struct drm_mm mm;
• spinlock_t mm_lock; int as; atomic_t as_count; struct list_head list;

@@ -106,9 +110,7 @@ struct panfrost_file_priv { struct drm_sched_entity sched_entity[NUM_JOB_SLOTS];

• struct panfrost_mmu mmu;
• struct drm_mm mm;
• spinlock_t mm_lock;

• struct panfrost_mmu *mmu; };

static inline struct panfrost_device *to_panfrost_device(struct drm_device *ddev) diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c index 273d67e251c2..41e574742a3c 100644 --- a/drivers/gpu/drm/panfrost/panfrost_drv.c +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c @@ -418,7 +418,7 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data, * anyway, so let's not bother. */ if (!list_is_singular(&bo->mappings.list) ||

•     WARN_ON_ONCE(first->mmu != &priv->mmu)) {
  

•     WARN_ON_ONCE(first->mmu != priv->mmu)) {
  ret = -EINVAL;
  goto out_unlock_mappings;
  

  }

@@ -450,32 +450,6 @@ int panfrost_unstable_ioctl_check(void) return 0; } -#define PFN_4G (SZ_4G >> PAGE_SHIFT) -#define PFN_4G_MASK (PFN_4G - 1) -#define PFN_16M (SZ_16M >> PAGE_SHIFT)

-static void panfrost_drm_mm_color_adjust(const struct drm_mm_node *node,

• 			 unsigned long color,
  

• 			 u64 *start, u64 *end)
  

-{

• /* Executable buffers can't start or end on a 4GB boundary */
• if (!(color & PANFROST_BO_NOEXEC)) {

• u64 next_seg;
  

• if ((*start & PFN_4G_MASK) == 0)
  

• 	(*start)++;
  

• if ((*end & PFN_4G_MASK) == 0)
  

• 	(*end)--;
  

• next_seg = ALIGN(*start, PFN_4G);
  

• if (next_seg - *start <= PFN_16M)
  

• 	*start = next_seg + 1;
  

• *end = min(*end, ALIGN(*start, PFN_4G) - 1);
  

• }

-}

• static int panfrost_open(struct drm_device *dev, struct drm_file *file) {

@@ -490,15 +464,11 @@ panfrost_open(struct drm_device *dev, struct drm_file *file) panfrost_priv->pfdev = pfdev; file->driver_priv = panfrost_priv;

• spin_lock_init(&panfrost_priv->mm_lock);
• /* 4G enough for now. can be 48-bit */
• drm_mm_init(&panfrost_priv->mm, SZ_32M >> PAGE_SHIFT, (SZ_4G - SZ_32M) >> PAGE_SHIFT);
• panfrost_priv->mm.color_adjust = panfrost_drm_mm_color_adjust;
• ret = panfrost_mmu_pgtable_alloc(panfrost_priv);
• if (ret)

• goto err_pgtable;
  

• panfrost_priv->mmu = panfrost_mmu_ctx_create(pfdev);
• if (IS_ERR(panfrost_priv->mmu)) {

• ret = PTR_ERR(panfrost_priv->mmu);
  

• goto err_free;
  

• }

ret = panfrost_job_open(panfrost_priv); if (ret) @@ -507,9 +477,8 @@ panfrost_open(struct drm_device *dev, struct drm_file *file) return 0; err_job:

• panfrost_mmu_pgtable_free(panfrost_priv);

-err_pgtable:

• drm_mm_takedown(&panfrost_priv->mm);

• panfrost_mmu_ctx_put(panfrost_priv->mmu);

+err_free: kfree(panfrost_priv); return ret; } @@ -522,8 +491,7 @@ panfrost_postclose(struct drm_device *dev, struct drm_file *file) panfrost_perfcnt_close(file); panfrost_job_close(panfrost_priv);

• panfrost_mmu_pgtable_free(panfrost_priv);
• drm_mm_takedown(&panfrost_priv->mm);

• panfrost_mmu_ctx_put(panfrost_priv->mmu); kfree(panfrost_priv); }

diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c index 17b654e1eb94..406e595f99e4 100644 --- a/drivers/gpu/drm/panfrost/panfrost_gem.c +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c @@ -60,7 +60,7 @@ panfrost_gem_mapping_get(struct panfrost_gem_object *bo, mutex_lock(&bo->mappings.lock); list_for_each_entry(iter, &bo->mappings.list, node) {

• if (iter->mmu == &priv->mmu) {
  

• if (iter->mmu == priv->mmu) {
  kref_get(&iter->refcount);
  mapping = iter;
  break;
  

@@ -74,16 +74,13 @@ panfrost_gem_mapping_get(struct panfrost_gem_object *bo, static void panfrost_gem_teardown_mapping(struct panfrost_gem_mapping *mapping) {

• struct panfrost_file_priv *priv;
• if (mapping->active) panfrost_mmu_unmap(mapping);

• priv = container_of(mapping->mmu, struct panfrost_file_priv, mmu);
• spin_lock(&priv->mm_lock);

• spin_lock(&mapping->mmu->mm_lock); if (drm_mm_node_allocated(&mapping->mmnode)) drm_mm_remove_node(&mapping->mmnode);

• spin_unlock(&priv->mm_lock);

• spin_unlock(&mapping->mmu->mm_lock); }

static void panfrost_gem_mapping_release(struct kref *kref) @@ -94,6 +91,7 @@ static void panfrost_gem_mapping_release(struct kref *kref) panfrost_gem_teardown_mapping(mapping); drm_gem_object_put_unlocked(&mapping->obj->base.base);

• panfrost_mmu_ctx_put(mapping->mmu); kfree(mapping); }

@@ -145,11 +143,11 @@ int panfrost_gem_open(struct drm_gem_object *obj, struct drm_file *file_priv) else align = size >= SZ_2M ? SZ_2M >> PAGE_SHIFT : 0;

• mapping->mmu = &priv->mmu;
• spin_lock(&priv->mm_lock);
• ret = drm_mm_insert_node_generic(&priv->mm, &mapping->mmnode,

• mapping->mmu = panfrost_mmu_ctx_get(priv->mmu);
• spin_lock(&mapping->mmu->mm_lock);
• ret = drm_mm_insert_node_generic(&mapping->mmu->mm, &mapping->mmnode, size >> PAGE_SHIFT, align, color, 0);

• spin_unlock(&priv->mm_lock);

• spin_unlock(&mapping->mmu->mm_lock); if (ret) goto err;

@@ -178,7 +176,7 @@ void panfrost_gem_close(struct drm_gem_object *obj, struct drm_file *file_priv) mutex_lock(&bo->mappings.lock); list_for_each_entry(iter, &bo->mappings.list, node) {

• if (iter->mmu == &priv->mmu) {
  

• if (iter->mmu == priv->mmu) {
  mapping = iter;
  list_del(&iter->node);
  break;
  

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c index 4d383831c1fc..b0716e49eeca 100644 --- a/drivers/gpu/drm/panfrost/panfrost_job.c +++ b/drivers/gpu/drm/panfrost/panfrost_job.c @@ -154,7 +154,7 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js) return; }

• cfg = panfrost_mmu_as_get(pfdev, &job->file_priv->mmu);

• cfg = panfrost_mmu_as_get(pfdev, job->file_priv->mmu); panfrost_devfreq_record_busy(pfdev);

job_write(pfdev, JS_HEAD_NEXT_LO(js), jc_head & 0xFFFFFFFF); @@ -481,7 +481,7 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data) if (job) { pfdev->jobs[j] = NULL;

• 		panfrost_mmu_as_put(pfdev, &job->file_priv->mmu);
  

• 		panfrost_mmu_as_put(pfdev, job->file_priv->mmu);
  	panfrost_devfreq_record_idle(pfdev);
  

dma_fence_signal_locked(job->done_fence); diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index 763cfca886a7..f70d5a75cbd5 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -1,5 +1,8 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright 2019 Linaro, Ltd, Rob Herring robh@kernel.org */

+#include <drm/panfrost_drm.h>

• #include <linux/atomic.h> #include <linux/bitfield.h> #include <linux/delay.h>

@@ -332,7 +335,7 @@ static void mmu_tlb_inv_context_s1(void *cookie) static void mmu_tlb_sync_context(void *cookie) {

• //struct panfrost_device *pfdev = cookie;

• //struct panfrost_mmu *mmu = cookie; // TODO: Wait 1000 GPU cycles for HW_ISSUE_6367/T60X }

@@ -354,56 +357,10 @@ static const struct iommu_flush_ops mmu_tlb_ops = { .tlb_flush_leaf = mmu_tlb_flush_leaf, }; -int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv *priv) -{

• struct panfrost_mmu *mmu = &priv->mmu;
• struct panfrost_device *pfdev = priv->pfdev;
• INIT_LIST_HEAD(&mmu->list);
• mmu->as = -1;
• mmu->pgtbl_cfg = (struct io_pgtable_cfg) {

• .pgsize_bitmap	= SZ_4K | SZ_2M,
  

• .ias		= FIELD_GET(0xff, pfdev->features.mmu_features),
  

• .oas		= FIELD_GET(0xff00, pfdev->features.mmu_features),
  

• .tlb		= &mmu_tlb_ops,
  

• .iommu_dev	= pfdev->dev,
  

• };
• mmu->pgtbl_ops = alloc_io_pgtable_ops(ARM_MALI_LPAE, &mmu->pgtbl_cfg,

• 			      priv);
  

• if (!mmu->pgtbl_ops)

• return -EINVAL;
  

• return 0;

-}

-void panfrost_mmu_pgtable_free(struct panfrost_file_priv *priv) -{

• struct panfrost_device *pfdev = priv->pfdev;
• struct panfrost_mmu *mmu = &priv->mmu;
• spin_lock(&pfdev->as_lock);
• if (mmu->as >= 0) {

• pm_runtime_get_noresume(pfdev->dev);
  

• if (pm_runtime_active(pfdev->dev))
  

• 	panfrost_mmu_disable(pfdev, mmu->as);
  

• pm_runtime_put_autosuspend(pfdev->dev);
  

• clear_bit(mmu->as, &pfdev->as_alloc_mask);
  

• clear_bit(mmu->as, &pfdev->as_in_use_mask);
  

• list_del(&mmu->list);
  

• }
• spin_unlock(&pfdev->as_lock);
• free_io_pgtable_ops(mmu->pgtbl_ops);

-}

• static struct panfrost_gem_mapping * addr_to_mapping(struct panfrost_device *pfdev, int as, u64 addr) { struct panfrost_gem_mapping *mapping = NULL;
• struct panfrost_file_priv *priv; struct drm_mm_node *node; u64 offset = addr >> PAGE_SHIFT; struct panfrost_mmu *mmu;

@@ -416,11 +373,10 @@ addr_to_mapping(struct panfrost_device *pfdev, int as, u64 addr) goto out; found_mmu:

• priv = container_of(mmu, struct panfrost_file_priv, mmu);

• spin_lock(&priv->mm_lock);

• spin_lock(&mmu->mm_lock);

• drm_mm_for_each_node(node, &priv->mm) {

• drm_mm_for_each_node(node, &mmu->mm) { if (offset >= node->start && offset < (node->start + node->size)) { mapping = drm_mm_node_to_panfrost_mapping(node);

@@ -430,7 +386,7 @@ addr_to_mapping(struct panfrost_device *pfdev, int as, u64 addr) } }

• spin_unlock(&priv->mm_lock);

• spin_unlock(&mmu->mm_lock); out: spin_unlock(&pfdev->as_lock); return mapping;

@@ -537,6 +493,106 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, return ret; } +static void panfrost_mmu_release_ctx(struct kref *kref) +{

• struct panfrost_mmu *mmu = container_of(kref, struct panfrost_mmu,

• 				refcount);
  

• struct panfrost_device *pfdev = mmu->pfdev;
• spin_lock(&pfdev->as_lock);
• if (mmu->as >= 0) {

• pm_runtime_get_noresume(pfdev->dev);
  

• if (pm_runtime_active(pfdev->dev))
  

• 	panfrost_mmu_disable(pfdev, mmu->as);
  

• pm_runtime_put_autosuspend(pfdev->dev);
  

• clear_bit(mmu->as, &pfdev->as_alloc_mask);
  

• clear_bit(mmu->as, &pfdev->as_in_use_mask);
  

• list_del(&mmu->list);
  

• }
• spin_unlock(&pfdev->as_lock);
• free_io_pgtable_ops(mmu->pgtbl_ops);
• drm_mm_takedown(&mmu->mm);
• kfree(mmu);

+}

+void panfrost_mmu_ctx_put(struct panfrost_mmu *mmu) +{

• kref_put(&mmu->refcount, panfrost_mmu_release_ctx);

+}

+struct panfrost_mmu *panfrost_mmu_ctx_get(struct panfrost_mmu *mmu) +{

• kref_get(&mmu->refcount);
• return mmu;

+}

+#define PFN_4G (SZ_4G >> PAGE_SHIFT) +#define PFN_4G_MASK (PFN_4G - 1) +#define PFN_16M (SZ_16M >> PAGE_SHIFT)

+static void panfrost_drm_mm_color_adjust(const struct drm_mm_node *node,

• 			 unsigned long color,
  

• 			 u64 *start, u64 *end)
  

+{

• /* Executable buffers can't start or end on a 4GB boundary */
• if (!(color & PANFROST_BO_NOEXEC)) {

• u64 next_seg;
  

• if ((*start & PFN_4G_MASK) == 0)
  

• 	(*start)++;
  

• if ((*end & PFN_4G_MASK) == 0)
  

• 	(*end)--;
  

• next_seg = ALIGN(*start, PFN_4G);
  

• if (next_seg - *start <= PFN_16M)
  

• 	*start = next_seg + 1;
  

• *end = min(*end, ALIGN(*start, PFN_4G) - 1);
  

• }

+}

+struct panfrost_mmu *panfrost_mmu_ctx_create(struct panfrost_device *pfdev) +{

• struct panfrost_mmu *mmu;
• mmu = kzalloc(sizeof(*mmu), GFP_KERNEL);
• if (!mmu)

• return ERR_PTR(-ENOMEM);
  

• mmu->pfdev = pfdev;
• spin_lock_init(&mmu->mm_lock);
• /* 4G enough for now. can be 48-bit */
• drm_mm_init(&mmu->mm, SZ_32M >> PAGE_SHIFT, (SZ_4G - SZ_32M) >> PAGE_SHIFT);
• mmu->mm.color_adjust = panfrost_drm_mm_color_adjust;
• INIT_LIST_HEAD(&mmu->list);
• mmu->as = -1;
• mmu->pgtbl_cfg = (struct io_pgtable_cfg) {

• .pgsize_bitmap	= SZ_4K | SZ_2M,
  

• .ias		= FIELD_GET(0xff, pfdev->features.mmu_features),
  

• .oas		= FIELD_GET(0xff00, pfdev->features.mmu_features),
  

• .tlb		= &mmu_tlb_ops,
  

• .iommu_dev	= pfdev->dev,
  

• };
• mmu->pgtbl_ops = alloc_io_pgtable_ops(ARM_MALI_LPAE, &mmu->pgtbl_cfg,

• 			      mmu);
  

• if (!mmu->pgtbl_ops) {

• kfree(mmu);
  

• return ERR_PTR(-EINVAL);
  

• }
• kref_init(&mmu->refcount);
• return mmu;

+}

• static const char *access_type_name(struct panfrost_device *pfdev, u32 fault_status) {

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.h b/drivers/gpu/drm/panfrost/panfrost_mmu.h index 44fc2edf63ce..cc2a0d307feb 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.h +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.h @@ -18,7 +18,8 @@ void panfrost_mmu_reset(struct panfrost_device *pfdev); u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu); void panfrost_mmu_as_put(struct panfrost_device *pfdev, struct panfrost_mmu *mmu); -int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv *priv); -void panfrost_mmu_pgtable_free(struct panfrost_file_priv *priv); +struct panfrost_mmu *panfrost_mmu_ctx_get(struct panfrost_mmu *mmu); +void panfrost_mmu_ctx_put(struct panfrost_mmu *mmu); +struct panfrost_mmu *panfrost_mmu_ctx_create(struct panfrost_device *pfdev); #endif