drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}()

Acquire the buffer object's reservation lock in drm_gem_pin() and
remove locking the drivers' GEM callbacks where necessary. Same for
unpin().

DRM drivers and memory managers modified by this patch will now have
correct dma-buf locking semantics: the caller is responsible for
holding the reservation lock when calling the pin or unpin callback.

DRM drivers and memory managers that are not modified will now be
protected against concurent invocation of their pin and unpin callbacks.

PRIME does not implement struct dma_buf_ops.pin, which requires
the caller to hold the reservation lock. It does implement struct
dma_buf_ops.attach, which requires to callee to acquire the
reservation lock. The PRIME code uses drm_gem_pin(), so locks
are now taken as specified. Same for unpin and detach.

The patch harmonizes GEM pin and unpin to have non-interruptible
reservation locking across all drivers, as is already the case for
vmap and vunmap. This affects gem-shmem, gem-vram, loongson, qxl and
radeon.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Zack Rusin <zack.rusin@broadcom.com>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> # virtio-gpu
Link: https://patchwork.freedesktop.org/patch/msgid/20240227113853.8464-10-tzimmermann@suse.de

10 files changed, 33 insertions, 95 deletions

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 44a948b80ee1..e0f80c6a7096 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1161,7 +1161,7 @@ void drm_gem_print_info(struct drm_printer *p, unsigned int indent,
 		obj->funcs->print_info(p, indent, obj);
 }
 
-int drm_gem_pin(struct drm_gem_object *obj)
+int drm_gem_pin_locked(struct drm_gem_object *obj)
 {
 	if (obj->funcs->pin)
 		return obj->funcs->pin(obj);
@@ -1169,12 +1169,30 @@ int drm_gem_pin(struct drm_gem_object *obj)
 	return 0;
 }
 
-void drm_gem_unpin(struct drm_gem_object *obj)
+void drm_gem_unpin_locked(struct drm_gem_object *obj)
 {
 	if (obj->funcs->unpin)
 		obj->funcs->unpin(obj);
 }
 
+int drm_gem_pin(struct drm_gem_object *obj)
+{
+	int ret;
+
+	dma_resv_lock(obj->resv, NULL);
+	ret = drm_gem_pin_locked(obj);
+	dma_resv_unlock(obj->resv);
+
+	return ret;
+}
+
+void drm_gem_unpin(struct drm_gem_object *obj)
+{
+	dma_resv_lock(obj->resv, NULL);
+	drm_gem_unpin_locked(obj);
+	dma_resv_unlock(obj->resv);
+}
+
 int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map)
 {
 	int ret;
diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 15029d89badf..5a16b3e0a413 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -774,11 +774,6 @@ EXPORT_SYMBOL(drm_gem_vram_simple_display_pipe_cleanup_fb);
 static int drm_gem_vram_object_pin(struct drm_gem_object *gem)
 {
 	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
-	int ret;
-
-	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
-	if (ret)
-		return ret;
 
 	/*
 	 * Fbdev console emulation is the use case of these PRIME
@@ -789,10 +784,7 @@ static int drm_gem_vram_object_pin(struct drm_gem_object *gem)
 	 * the buffer to be pinned to VRAM, implement a callback that
 	 * sets the flags accordingly.
 	 */
-	ret = drm_gem_vram_pin_locked(gbo, 0);
-	ttm_bo_unreserve(&gbo->bo);
-
-	return ret;
+	return drm_gem_vram_pin_locked(gbo, 0);
 }
 
 /**
@@ -803,13 +795,8 @@ static int drm_gem_vram_object_pin(struct drm_gem_object *gem)
 static void drm_gem_vram_object_unpin(struct drm_gem_object *gem)
 {
 	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
-	int ret;
 
-	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
-	if (ret)
-		return;
 	drm_gem_vram_unpin_locked(gbo);
-	ttm_bo_unreserve(&gbo->bo);
 }
 
 /**
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index d69744c9ac15..2215baef9a3e 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -173,6 +173,8 @@ void drm_gem_release(struct drm_device *dev, struct drm_file *file_private);
 void drm_gem_print_info(struct drm_printer *p, unsigned int indent,
 			const struct drm_gem_object *obj);
 
+int drm_gem_pin_locked(struct drm_gem_object *obj);
+void drm_gem_unpin_locked(struct drm_gem_object *obj);
 int drm_gem_pin(struct drm_gem_object *obj);
 void drm_gem_unpin(struct drm_gem_object *obj);
 int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map);
diff --git a/drivers/gpu/drm/loongson/lsdc_gem.c b/drivers/gpu/drm/loongson/lsdc_gem.c
index 04293df2f0de..a720d8f53209 100644
--- a/drivers/gpu/drm/loongson/lsdc_gem.c
+++ b/drivers/gpu/drm/loongson/lsdc_gem.c
@@ -19,33 +19,24 @@ static int lsdc_gem_prime_pin(struct drm_gem_object *obj)
 	struct lsdc_bo *lbo = gem_to_lsdc_bo(obj);
 	int ret;
 
-	ret = lsdc_bo_reserve(lbo);
-	if (unlikely(ret))
-		return ret;
+	dma_resv_assert_held(obj->resv);
 
 	ret = lsdc_bo_pin(lbo, LSDC_GEM_DOMAIN_GTT, NULL);
 	if (likely(ret == 0))
 		lbo->sharing_count++;
 
-	lsdc_bo_unreserve(lbo);
-
 	return ret;
 }
 
 static void lsdc_gem_prime_unpin(struct drm_gem_object *obj)
 {
 	struct lsdc_bo *lbo = gem_to_lsdc_bo(obj);
-	int ret;
 
-	ret = lsdc_bo_reserve(lbo);
-	if (unlikely(ret))
-		return;
+	dma_resv_assert_held(obj->resv);
 
 	lsdc_bo_unpin(lbo);
 	if (lbo->sharing_count)
 		lbo->sharing_count--;
-
-	lsdc_bo_unreserve(lbo);
 }
 
 static struct sg_table *lsdc_gem_prime_get_sg_table(struct drm_gem_object *obj)
diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c b/drivers/gpu/drm/msm/msm_gem_prime.c
index 0d22df53ab98..ee267490c935 100644
--- a/drivers/gpu/drm/msm/msm_gem_prime.c
+++ b/drivers/gpu/drm/msm/msm_gem_prime.c
@@ -53,11 +53,9 @@ int msm_gem_prime_pin(struct drm_gem_object *obj)
 	if (obj->import_attach)
 		return 0;
 
-	msm_gem_lock(obj);
 	pages = msm_gem_pin_pages_locked(obj);
 	if (IS_ERR(pages))
 		ret = PTR_ERR(pages);
-	msm_gem_unlock(obj);
 
 	return ret;
 }
@@ -67,7 +65,5 @@ void msm_gem_prime_unpin(struct drm_gem_object *obj)
 	if (obj->import_attach)
 		return;
 
-	msm_gem_lock(obj);
 	msm_gem_unpin_pages_locked(obj);
-	msm_gem_unlock(obj);
 }
diff --git a/drivers/gpu/drm/nouveau/nouveau_prime.c b/drivers/gpu/drm/nouveau/nouveau_prime.c
index 774f9bd03110..b58ab595faf8 100644
--- a/drivers/gpu/drm/nouveau/nouveau_prime.c
+++ b/drivers/gpu/drm/nouveau/nouveau_prime.c
@@ -86,17 +86,12 @@ unlock:
 int nouveau_gem_prime_pin(struct drm_gem_object *obj)
 {
 	struct nouveau_bo *nvbo = nouveau_gem_object(obj);
-	struct ttm_buffer_object *bo = &nvbo->bo;
 	int ret;
 
-	ret = ttm_bo_reserve(bo, false, false, NULL);
-	if (ret)
-		return -EINVAL;
 	/* pin buffer into GTT */
 	ret = nouveau_bo_pin_locked(nvbo, NOUVEAU_GEM_DOMAIN_GART, false);
 	if (ret)
 		ret = -EINVAL;
-	ttm_bo_unreserve(bo);
 
 	return ret;
 }
@@ -104,14 +99,8 @@ int nouveau_gem_prime_pin(struct drm_gem_object *obj)
 void nouveau_gem_prime_unpin(struct drm_gem_object *obj)
 {
 	struct nouveau_bo *nvbo = nouveau_gem_object(obj);
-	struct ttm_buffer_object *bo = &nvbo->bo;
-	int ret;
 
-	ret = ttm_bo_reserve(bo, false, false, NULL);
-	if (ret)
-		return;
 	nouveau_bo_unpin_locked(nvbo);
-	ttm_bo_unreserve(bo);
 }
 
 struct dma_buf *nouveau_gem_prime_export(struct drm_gem_object *gobj,
diff --git a/drivers/gpu/drm/qxl/qxl_prime.c b/drivers/gpu/drm/qxl/qxl_prime.c
index f2646603e12e..19bf551a7b31 100644
--- a/drivers/gpu/drm/qxl/qxl_prime.c
+++ b/drivers/gpu/drm/qxl/qxl_prime.c
@@ -31,27 +31,15 @@
 int qxl_gem_prime_pin(struct drm_gem_object *obj)
 {
 	struct qxl_bo *bo = gem_to_qxl_bo(obj);
-	int r;
 
-	r = qxl_bo_reserve(bo);
-	if (r)
-		return r;
-	r = qxl_bo_pin_locked(bo);
-	qxl_bo_unreserve(bo);
-
-	return r;
+	return qxl_bo_pin_locked(bo);
 }
 
 void qxl_gem_prime_unpin(struct drm_gem_object *obj)
 {
 	struct qxl_bo *bo = gem_to_qxl_bo(obj);
-	int r;
 
-	r = qxl_bo_reserve(bo);
-	if (r)
-		return;
 	qxl_bo_unpin_locked(bo);
-	qxl_bo_unreserve(bo);
 }
 
 struct sg_table *qxl_gem_prime_get_sg_table(struct drm_gem_object *obj)
diff --git a/drivers/gpu/drm/radeon/radeon_prime.c b/drivers/gpu/drm/radeon/radeon_prime.c
index b3cfc99f4d7e..a77881f035e7 100644
--- a/drivers/gpu/drm/radeon/radeon_prime.c
+++ b/drivers/gpu/drm/radeon/radeon_prime.c
@@ -73,32 +73,21 @@ int radeon_gem_prime_pin(struct drm_gem_object *obj)
 	struct radeon_bo *bo = gem_to_radeon_bo(obj);
 	int ret = 0;
 
-	ret = radeon_bo_reserve(bo, false);
-	if (unlikely(ret != 0))
-		return ret;
-
 	/* pin buffer into GTT */
 	ret = radeon_bo_pin(bo, RADEON_GEM_DOMAIN_GTT, NULL);
 	if (likely(ret == 0))
 		bo->prime_shared_count++;
 
-	radeon_bo_unreserve(bo);
 	return ret;
 }
 
 void radeon_gem_prime_unpin(struct drm_gem_object *obj)
 {
 	struct radeon_bo *bo = gem_to_radeon_bo(obj);
-	int ret = 0;
-
-	ret = radeon_bo_reserve(bo, false);
-	if (unlikely(ret != 0))
-		return;
 
 	radeon_bo_unpin(bo);
 	if (bo->prime_shared_count)
 		bo->prime_shared_count--;
-	radeon_bo_unreserve(bo);
 }
 
 
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
index 12787bb9c111..186150f41fbc 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
@@ -48,33 +48,20 @@ static void vmw_gem_object_close(struct drm_gem_object *obj,
 {
 }
 
-static int vmw_gem_pin_private(struct drm_gem_object *obj, bool do_pin)
+static int vmw_gem_object_pin(struct drm_gem_object *obj)
 {
-	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(obj);
 	struct vmw_bo *vbo = to_vmw_bo(obj);
-	int ret;
-
-	ret = ttm_bo_reserve(bo, false, false, NULL);
-	if (unlikely(ret != 0))
-		goto err;
-
-	vmw_bo_pin_reserved(vbo, do_pin);
-
-	ttm_bo_unreserve(bo);
-
-err:
-	return ret;
-}
 
+	vmw_bo_pin_reserved(vbo, true);
 
-static int vmw_gem_object_pin(struct drm_gem_object *obj)
-{
-	return vmw_gem_pin_private(obj, true);
+	return 0;
 }
 
 static void vmw_gem_object_unpin(struct drm_gem_object *obj)
 {
-	vmw_gem_pin_private(obj, false);
+	struct vmw_bo *vbo = to_vmw_bo(obj);
+
+	vmw_bo_pin_reserved(vbo, false);
 }
 
 static struct sg_table *vmw_gem_object_get_sg_table(struct drm_gem_object *obj)
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index eb12aa9a8c55..efbc9f27312b 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -175,15 +175,8 @@ static inline void drm_gem_shmem_object_print_info(struct drm_printer *p, unsign
 static inline int drm_gem_shmem_object_pin(struct drm_gem_object *obj)
 {
 	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-	int ret;
 
-	ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
-	if (ret)
-		return ret;
-	ret = drm_gem_shmem_pin_locked(shmem);
-	dma_resv_unlock(shmem->base.resv);
-
-	return ret;
+	return drm_gem_shmem_pin_locked(shmem);
 }
 
 /**
@@ -197,9 +190,7 @@ static inline void drm_gem_shmem_object_unpin(struct drm_gem_object *obj)
 {
 	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 
-	dma_resv_lock(shmem->base.resv, NULL);
 	drm_gem_shmem_unpin_locked(shmem);
-	dma_resv_unlock(shmem->base.resv);
 }
 
 /**