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Subject[PATCH v5 8/9] drm/vmwgfx: Implement an infrastructure for read-coherent resources
Date
From: Thomas Hellstrom <thellstrom@vmware.com>

Similar to write-coherent resources, make sure that from the user-space
point of view, GPU rendered contents is automatically available for
reading by the CPU.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>
---
drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 7 +-
drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c | 73 ++++++++++++-
drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 103 +++++++++++++++++-
drivers/gpu/drm/vmwgfx/vmwgfx_resource_priv.h | 2 +
drivers/gpu/drm/vmwgfx/vmwgfx_validation.c | 3 +-
5 files changed, 177 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 9b347923196f..dae3a39bf402 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -689,7 +689,8 @@ extern void vmw_resource_unreference(struct vmw_resource **p_res);
extern struct vmw_resource *vmw_resource_reference(struct vmw_resource *res);
extern struct vmw_resource *
vmw_resource_reference_unless_doomed(struct vmw_resource *res);
-extern int vmw_resource_validate(struct vmw_resource *res, bool intr);
+extern int vmw_resource_validate(struct vmw_resource *res, bool intr,
+ bool dirtying);
extern int vmw_resource_reserve(struct vmw_resource *res, bool interruptible,
bool no_backup);
extern bool vmw_resource_needs_backup(const struct vmw_resource *res);
@@ -733,6 +734,8 @@ void vmw_resource_mob_attach(struct vmw_resource *res);
void vmw_resource_mob_detach(struct vmw_resource *res);
void vmw_resource_dirty_update(struct vmw_resource *res, pgoff_t start,
pgoff_t end);
+int vmw_resources_clean(struct vmw_buffer_object *vbo, pgoff_t start,
+ pgoff_t end, pgoff_t *num_prefault);

/**
* vmw_resource_mob_attached - Whether a resource currently has a mob attached
@@ -1427,6 +1430,8 @@ int vmw_bo_dirty_add(struct vmw_buffer_object *vbo);
void vmw_bo_dirty_transfer_to_res(struct vmw_resource *res);
void vmw_bo_dirty_clear_res(struct vmw_resource *res);
void vmw_bo_dirty_release(struct vmw_buffer_object *vbo);
+void vmw_bo_dirty_unmap(struct vmw_buffer_object *vbo,
+ pgoff_t start, pgoff_t end);
vm_fault_t vmw_bo_vm_fault(struct vm_fault *vmf);
vm_fault_t vmw_bo_vm_mkwrite(struct vm_fault *vmf);

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
index 8d154f90bdc0..730c51e397dd 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
@@ -153,7 +153,6 @@ static void vmw_bo_dirty_scan_mkwrite(struct vmw_buffer_object *vbo)
}
}

-
/**
* vmw_bo_dirty_scan - Scan for dirty pages and add them to the dirty
* tracking structure
@@ -171,6 +170,51 @@ void vmw_bo_dirty_scan(struct vmw_buffer_object *vbo)
vmw_bo_dirty_scan_mkwrite(vbo);
}

+/**
+ * vmw_bo_dirty_pre_unmap - write-protect and pick up dirty pages before
+ * an unmap_mapping_range operation.
+ * @vbo: The buffer object,
+ * @start: First page of the range within the buffer object.
+ * @end: Last page of the range within the buffer object + 1.
+ *
+ * If we're using the _PAGETABLE scan method, we may leak dirty pages
+ * when calling unmap_mapping_range(). This function makes sure we pick
+ * up all dirty pages.
+ */
+static void vmw_bo_dirty_pre_unmap(struct vmw_buffer_object *vbo,
+ pgoff_t start, pgoff_t end)
+{
+ struct vmw_bo_dirty *dirty = vbo->dirty;
+ unsigned long offset = drm_vma_node_start(&vbo->base.vma_node);
+ struct address_space *mapping = vbo->base.bdev->dev_mapping;
+
+ if (dirty->method != VMW_BO_DIRTY_PAGETABLE || start >= end)
+ return;
+
+ apply_as_wrprotect(mapping, start + offset, end - start);
+ apply_as_clean(mapping, start + offset, end - start, offset,
+ &dirty->bitmap[0], &dirty->start, &dirty->end);
+}
+
+/**
+ * vmw_bo_dirty_unmap - Clear all ptes pointing to a range within a bo
+ * @vbo: The buffer object,
+ * @start: First page of the range within the buffer object.
+ * @end: Last page of the range within the buffer object + 1.
+ *
+ * This is similar to ttm_bo_unmap_virtual_locked() except it takes a subrange.
+ */
+void vmw_bo_dirty_unmap(struct vmw_buffer_object *vbo,
+ pgoff_t start, pgoff_t end)
+{
+ unsigned long offset = drm_vma_node_start(&vbo->base.vma_node);
+ struct address_space *mapping = vbo->base.bdev->dev_mapping;
+
+ vmw_bo_dirty_pre_unmap(vbo, start, end);
+ unmap_shared_mapping_range(mapping, (offset + start) << PAGE_SHIFT,
+ (loff_t) (end - start) << PAGE_SHIFT);
+}
+
/**
* vmw_bo_dirty_add - Add a dirty-tracking user to a buffer object
* @vbo: The buffer object
@@ -389,21 +433,40 @@ vm_fault_t vmw_bo_vm_fault(struct vm_fault *vmf)
if (ret)
return ret;

+ num_prefault = (vma->vm_flags & VM_RAND_READ) ? 1 :
+ TTM_BO_VM_NUM_PREFAULT;
+
+ if (vbo->dirty) {
+ pgoff_t allowed_prefault;
+ unsigned long page_offset;
+
+ page_offset = vmf->pgoff - drm_vma_node_start(&bo->vma_node);
+ if (page_offset >= bo->num_pages ||
+ vmw_resources_clean(vbo, page_offset,
+ page_offset + PAGE_SIZE,
+ &allowed_prefault)) {
+ ret = VM_FAULT_SIGBUS;
+ goto out_unlock;
+ }
+
+ num_prefault = min(num_prefault, allowed_prefault);
+ }
+
/*
- * This will cause mkwrite() to be called for each pte on
- * write-enable vmas.
+ * If we don't track dirty using the MKWRITE method, make sure
+ * sure the page protection is write-enabled so we don't get
+ * a lot of unnecessary write faults.
*/
if (vbo->dirty && vbo->dirty->method == VMW_BO_DIRTY_MKWRITE)
prot = vma->vm_page_prot;
else
prot = vm_get_page_prot(vma->vm_flags);

- num_prefault = (vma->vm_flags & VM_RAND_READ) ? 0 :
- TTM_BO_VM_NUM_PREFAULT;
ret = ttm_bo_vm_fault_reserved(vmf, prot, num_prefault);
if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
return ret;

+out_unlock:
reservation_object_unlock(bo->resv);
return ret;
}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index b84dd5953886..d70ee0df5c13 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -395,7 +395,8 @@ static int vmw_resource_buf_alloc(struct vmw_resource *res,
* should be retried once resources have been freed up.
*/
static int vmw_resource_do_validate(struct vmw_resource *res,
- struct ttm_validate_buffer *val_buf)
+ struct ttm_validate_buffer *val_buf,
+ bool dirtying)
{
int ret = 0;
const struct vmw_res_func *func = res->func;
@@ -437,6 +438,15 @@ static int vmw_resource_do_validate(struct vmw_resource *res,
* the resource.
*/
if (res->dirty) {
+ if (dirtying && !res->res_dirty) {
+ pgoff_t start = res->backup_offset >> PAGE_SHIFT;
+ pgoff_t end = __KERNEL_DIV_ROUND_UP
+ (res->backup_offset + res->backup_size,
+ PAGE_SIZE);
+
+ vmw_bo_dirty_unmap(res->backup, start, end);
+ }
+
vmw_bo_dirty_transfer_to_res(res);
return func->dirty_sync(res);
}
@@ -681,6 +691,7 @@ static int vmw_resource_do_evict(struct ww_acquire_ctx *ticket,
* to the device.
* @res: The resource to make visible to the device.
* @intr: Perform waits interruptible if possible.
+ * @dirtying: Pending GPU operation will dirty the resource
*
* On succesful return, any backup DMA buffer pointed to by @res->backup will
* be reserved and validated.
@@ -690,7 +701,8 @@ static int vmw_resource_do_evict(struct ww_acquire_ctx *ticket,
* Return: Zero on success, -ERESTARTSYS if interrupted, negative error code
* on failure.
*/
-int vmw_resource_validate(struct vmw_resource *res, bool intr)
+int vmw_resource_validate(struct vmw_resource *res, bool intr,
+ bool dirtying)
{
int ret;
struct vmw_resource *evict_res;
@@ -707,7 +719,7 @@ int vmw_resource_validate(struct vmw_resource *res, bool intr)
if (res->backup)
val_buf.bo = &res->backup->base;
do {
- ret = vmw_resource_do_validate(res, &val_buf);
+ ret = vmw_resource_do_validate(res, &val_buf, dirtying);
if (likely(ret != -EBUSY))
break;

@@ -1007,7 +1019,7 @@ int vmw_resource_pin(struct vmw_resource *res, bool interruptible)
/* Do we really need to pin the MOB as well? */
vmw_bo_pin_reserved(vbo, true);
}
- ret = vmw_resource_validate(res, interruptible);
+ ret = vmw_resource_validate(res, interruptible, true);
if (vbo)
ttm_bo_unreserve(&vbo->base);
if (ret)
@@ -1082,3 +1094,86 @@ void vmw_resource_dirty_update(struct vmw_resource *res, pgoff_t start,
res->func->dirty_range_add(res, start << PAGE_SHIFT,
end << PAGE_SHIFT);
}
+
+/**
+ * vmw_resources_clean - Clean resources intersecting a mob range
+ * @vbo: The mob buffer object
+ * @start: The mob page offset starting the range
+ * @end: The mob page offset ending the range
+ * @num_prefault: Returns how many pages including the first have been
+ * cleaned and are ok to prefault
+ */
+int vmw_resources_clean(struct vmw_buffer_object *vbo, pgoff_t start,
+ pgoff_t end, pgoff_t *num_prefault)
+{
+ struct rb_node *cur = vbo->res_tree.rb_node;
+ struct vmw_resource *found = NULL;
+ unsigned long res_start = start << PAGE_SHIFT;
+ unsigned long res_end = end << PAGE_SHIFT;
+ unsigned long last_cleaned = 0;
+
+ /*
+ * Find the resource with lowest backup_offset that intersects the
+ * range.
+ */
+ while (cur) {
+ struct vmw_resource *cur_res =
+ container_of(cur, struct vmw_resource, mob_node);
+
+ if (cur_res->backup_offset >= res_end) {
+ cur = cur->rb_left;
+ } else if (cur_res->backup_offset + cur_res->backup_size <=
+ res_start) {
+ cur = cur->rb_right;
+ } else {
+ found = cur_res;
+ cur = cur->rb_left;
+ /* Continue to look for resources with lower offsets */
+ }
+ }
+
+ /*
+ * In order of increasing backup_offset, clean dirty resorces
+ * intersecting the range.
+ */
+ while (found) {
+ if (found->res_dirty) {
+ int ret;
+
+ if (!found->func->clean)
+ return -EINVAL;
+
+ ret = found->func->clean(found);
+ if (ret)
+ return ret;
+
+ found->res_dirty = false;
+ }
+ last_cleaned = found->backup_offset + found->backup_size;
+ cur = rb_next(&found->mob_node);
+ if (!cur)
+ break;
+
+ found = container_of(cur, struct vmw_resource, mob_node);
+ if (found->backup_offset >= res_end)
+ break;
+ }
+
+ /*
+ * Set number of pages allowed prefaulting and fence the buffer object
+ */
+ *num_prefault = 1;
+ if (last_cleaned > res_start) {
+ struct ttm_buffer_object *bo = &vbo->base;
+
+ *num_prefault = __KERNEL_DIV_ROUND_UP(last_cleaned - res_start,
+ PAGE_SIZE);
+ vmw_bo_fence_single(bo, NULL);
+ if (bo->moving)
+ dma_fence_put(bo->moving);
+ bo->moving = dma_fence_get
+ (reservation_object_get_excl(bo->resv));
+ }
+
+ return 0;
+}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource_priv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_resource_priv.h
index c85144286cfe..3b7438b2d289 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource_priv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource_priv.h
@@ -77,6 +77,7 @@ struct vmw_user_resource_conv {
* @dirty_sync: Upload the dirty mob contents to the resource.
* @dirty_add_range: Add a sequential dirty range to the resource
* dirty tracker.
+ * @clean: Clean the resource.
*/
struct vmw_res_func {
enum vmw_res_type res_type;
@@ -101,6 +102,7 @@ struct vmw_res_func {
int (*dirty_sync)(struct vmw_resource *res);
void (*dirty_range_add)(struct vmw_resource *res, size_t start,
size_t end);
+ int (*clean)(struct vmw_resource *res);
};

/**
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
index 71349a7bae90..9aaf807ed73c 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
@@ -641,7 +641,8 @@ int vmw_validation_res_validate(struct vmw_validation_context *ctx, bool intr)
struct vmw_resource *res = val->res;
struct vmw_buffer_object *backup = res->backup;

- ret = vmw_resource_validate(res, intr);
+ ret = vmw_resource_validate(res, intr, val->dirty_set &&
+ val->dirty);
if (ret) {
if (ret != -ERESTARTSYS)
DRM_ERROR("Failed to validate resource.\n");
--
2.20.1
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