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Thomas Zimmermann

2024-Feb-27 10:14 UTC

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

Dma-buf locking semantics require the caller of pin and unpin to hold
the buffer's reservation lock. Fix DRM to adhere to the specs. This
enables to fix the locking in DRM's console emulation. Similar changes
for vmap and mmap have been posted at [1][2]

Most DRM drivers and memory managers acquire the buffer object's
reservation lock within their GEM pin and unpin callbacks. This
violates dma-buf locking semantics. We get away with it because PRIME
does not provide pin/unpin, but attach/detach, for which the locking
semantics is correct.

Patches 1 to 8 rework DRM GEM code in various implementations to
acquire the reservation lock when entering the pin and unpin callbacks.
This prepares them for the next patch. Drivers that are not affected
by these patches either don't acquire the reservation lock (amdgpu)
or don't need preparation (loongson).

Patch 9 moves reservation locking from the GEM pin/unpin callbacks
into drm_gem_pin() and drm_gem_unpin(). As PRIME uses these functions
internally it still gets the reservation lock.

With the updated GEM callbacks, the rest of the patchset fixes the
fbdev emulation's buffer locking. Fbdev emulation needs to keep its
GEM buffer object inplace while updating its content. This required
a implicit pinning and apparently amdgpu didn't do this at all.

Patch 10 introduces drm_client_buffer_vmap_local() and _vunmap_local().
The former function map a GEM buffer into the kernel's address space
with regular vmap operations, but keeps holding the reservation lock.
The _vunmap_local() helper undoes the vmap and releases the lock. The
updated GEM callbacks make this possible. Between the two calls, the
fbdev emulation can update the buffer content without have the buffer
moved or evicted. Update fbdev-generic to use vmap_local helpers,
which fix amdgpu. The idea of adding a "local vmap" has previously
been
attempted at [3] in a different form.

Patch 11 adds implicit pinning to the DRM client's regular vmap
helper so that long-term vmap'ed buffers won't be evicted. This only
affects fbdev-dma, but GEM DMA helpers don't require pinning. So
there are no practical changes.

Patches 12 and 13 remove implicit pinning from the vmap and vunmap
operations in gem-vram and qxl. These pin operations are not supposed
to be part of vmap code, but were required to keep the buffers in place
for fbdev emulation. With the conversion o ffbdev-generic to to
vmap_local helpers, that code can finally be removed.

Tested with amdgpu, nouveau, radeon, simpledrm and vc4.

[1] https://patchwork.freedesktop.org/series/106371/
[2] https://patchwork.freedesktop.org/series/116001/
[3] https://patchwork.freedesktop.org/series/84732/

Thomas Zimmermann (13):
  drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks
  drm/gem-vram: Acquire reservation lock in GEM pin/unpin callbacks
  drm/msm: Provide msm_gem_get_pages_locked()
  drm/msm: Acquire reservation lock in GEM pin/unpin callback
  drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked()
  drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks
  drm/qxl: Provide qxl_bo_{pin,unpin}_locked()
  drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks
  drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}()
  drm/fbdev-generic: Fix locking with drm_client_buffer_vmap_local()
  drm/client: Pin vmap'ed GEM buffers
  drm/gem-vram: Do not pin buffer objects for vmap
  drm/qxl: Do not pin buffer objects for vmap

 drivers/gpu/drm/drm_client.c            |  92 ++++++++++++++++++---
 drivers/gpu/drm/drm_fbdev_generic.c     |   4 +-
 drivers/gpu/drm/drm_gem.c               |  34 +++++++-
 drivers/gpu/drm/drm_gem_shmem_helper.c  |   6 +-
 drivers/gpu/drm/drm_gem_vram_helper.c   | 101 ++++++++++--------------
 drivers/gpu/drm/drm_internal.h          |   2 +
 drivers/gpu/drm/loongson/lsdc_gem.c     |  13 +--
 drivers/gpu/drm/msm/msm_gem.c           |  20 ++---
 drivers/gpu/drm/msm/msm_gem.h           |   4 +-
 drivers/gpu/drm/msm/msm_gem_prime.c     |  20 +++--
 drivers/gpu/drm/nouveau/nouveau_bo.c    |  43 +++++++---
 drivers/gpu/drm/nouveau/nouveau_bo.h    |   2 +
 drivers/gpu/drm/nouveau/nouveau_prime.c |   8 +-
 drivers/gpu/drm/qxl/qxl_object.c        |  26 +++---
 drivers/gpu/drm/qxl/qxl_object.h        |   2 +
 drivers/gpu/drm/qxl/qxl_prime.c         |   4 +-
 drivers/gpu/drm/radeon/radeon_prime.c   |  11 ---
 drivers/gpu/drm/vmwgfx/vmwgfx_gem.c     |  25 ++----
 include/drm/drm_client.h                |  10 +++
 include/drm/drm_gem.h                   |   3 +
 include/drm/drm_gem_shmem_helper.h      |   7 +-
 21 files changed, 265 insertions(+), 172 deletions(-)


base-commit: 7291e2e67dff0ff573900266382c9c9248a7dea5
prerequisite-patch-id: bdfa0e6341b30cc9d7647172760b3473007c1216
prerequisite-patch-id: bc27ac702099f481890ae2c7c4a9c531f4a62d64
prerequisite-patch-id: f5d4bf16dc45334254527c2e31ee21ba4582761c
prerequisite-patch-id: 734c87e610747779aa41be12eb9e4c984bdfa743
prerequisite-patch-id: 0aa359f6144c4015c140c8a6750be19099c676fb
prerequisite-patch-id: c67e5d886a47b7d0266d81100837557fda34cb24
prerequisite-patch-id: cbc453ee02fae02af22fbfdce56ab732c7a88c36
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 01/13] drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks

Export drm_gem_shmem_pin_locked() and acquire the reservation lock
directly in GEM pin callback. Same for unpin. Prepares for further
changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
gem-shmem accordingly by pushing locking out of the implementation.
A follow-up patch will fix locking for all GEM code at once.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c |  6 ++++--
 include/drm/drm_gem_shmem_helper.h     | 16 ++++++++++++++--
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c
b/drivers/gpu/drm/drm_gem_shmem_helper.c
index e435f986cd135..0ac3dddb917f3 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -228,7 +228,7 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object
*shmem)
 }
 EXPORT_SYMBOL(drm_gem_shmem_put_pages);
 
-static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
+int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
 {
 	int ret;
 
@@ -238,13 +238,15 @@ static int drm_gem_shmem_pin_locked(struct
drm_gem_shmem_object *shmem)
 
 	return ret;
 }
+EXPORT_SYMBOL(drm_gem_shmem_pin_locked);
 
-static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
+void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
 {
 	dma_resv_assert_held(shmem->base.resv);
 
 	drm_gem_shmem_put_pages(shmem);
 }
+EXPORT_SYMBOL(drm_gem_shmem_unpin_locked);
 
 /**
  * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
diff --git a/include/drm/drm_gem_shmem_helper.h
b/include/drm/drm_gem_shmem_helper.h
index bf0c31aa8fbe4..eb12aa9a8c556 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -108,6 +108,9 @@ void drm_gem_shmem_vunmap(struct drm_gem_shmem_object
*shmem,
 			  struct iosys_map *map);
 int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct
vm_area_struct *vma);
 
+int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem);
+void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem);
+
 int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv);
 
 static inline bool drm_gem_shmem_is_purgeable(struct drm_gem_shmem_object
*shmem)
@@ -172,8 +175,15 @@ 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 drm_gem_shmem_pin(shmem);
+	return ret;
 }
 
 /**
@@ -187,7 +197,9 @@ 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);
 
-	drm_gem_shmem_unpin(shmem);
+	dma_resv_lock(shmem->base.resv, NULL);
+	drm_gem_shmem_unpin_locked(shmem);
+	dma_resv_unlock(shmem->base.resv);
 }
 
 /**
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 02/13] drm/gem-vram: Acquire reservation lock in GEM pin/unpin callbacks

Acquire the reservation lock directly in GEM pin callback. Same for
unpin. Prepares for further changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
gem-vram accordingly by pushing locking out of the implementation.
A follow-up patch will fix locking for all GEM code at once.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/drm_gem_vram_helper.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c
b/drivers/gpu/drm/drm_gem_vram_helper.c
index 75f2eaf0d5b61..15029d89badf8 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -283,6 +283,8 @@ static int drm_gem_vram_pin_locked(struct
drm_gem_vram_object *gbo,
 	struct ttm_operation_ctx ctx = { false, false };
 	int ret;
 
+	dma_resv_assert_held(gbo->bo.base.resv);
+
 	if (gbo->bo.pin_count)
 		goto out;
 
@@ -338,6 +340,8 @@ EXPORT_SYMBOL(drm_gem_vram_pin);
 
 static void drm_gem_vram_unpin_locked(struct drm_gem_vram_object *gbo)
 {
+	dma_resv_assert_held(gbo->bo.base.resv);
+
 	ttm_bo_unpin(&gbo->bo);
 }
 
@@ -770,8 +774,14 @@ 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;
 
-	/* Fbdev console emulation is the use case of these PRIME
+	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
+	if (ret)
+		return ret;
+
+	/*
+	 * Fbdev console emulation is the use case of these PRIME
 	 * helpers. This may involve updating a hardware buffer from
 	 * a shadow FB. We pin the buffer to it's current location
 	 * (either video RAM or system memory) to prevent it from
@@ -779,7 +789,10 @@ 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.
 	 */
-	return drm_gem_vram_pin(gbo, 0);
+	ret = drm_gem_vram_pin_locked(gbo, 0);
+	ttm_bo_unreserve(&gbo->bo);
+
+	return ret;
 }
 
 /**
@@ -790,8 +803,13 @@ 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;
 
-	drm_gem_vram_unpin(gbo);
+	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
+	if (ret)
+		return;
+	drm_gem_vram_unpin_locked(gbo);
+	ttm_bo_unreserve(&gbo->bo);
 }
 
 /**
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 03/13] drm/msm: Provide msm_gem_get_pages_locked()

Rename msm_gem_pin_pages_locked() to msm_gem_get_pages_locked(). The
function doesn't pin any pages, but only acquires them. Renaming the
function makes the old name available.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/msm/msm_gem.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 175ee4ab8a6f7..bb729353d3a8d 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -219,7 +219,7 @@ static void put_pages(struct drm_gem_object *obj)
 	}
 }
 
-static struct page **msm_gem_pin_pages_locked(struct drm_gem_object *obj,
+static struct page **msm_gem_get_pages_locked(struct drm_gem_object *obj,
 					      unsigned madv)
 {
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
@@ -262,7 +262,7 @@ struct page **msm_gem_pin_pages(struct drm_gem_object *obj)
 	struct page **p;
 
 	msm_gem_lock(obj);
-	p = msm_gem_pin_pages_locked(obj, MSM_MADV_WILLNEED);
+	p = msm_gem_get_pages_locked(obj, MSM_MADV_WILLNEED);
 	if (!IS_ERR(p))
 		pin_obj_locked(obj);
 	msm_gem_unlock(obj);
@@ -489,7 +489,7 @@ int msm_gem_pin_vma_locked(struct drm_gem_object *obj,
struct msm_gem_vma *vma)
 
 	msm_gem_assert_locked(obj);
 
-	pages = msm_gem_pin_pages_locked(obj, MSM_MADV_WILLNEED);
+	pages = msm_gem_get_pages_locked(obj, MSM_MADV_WILLNEED);
 	if (IS_ERR(pages))
 		return PTR_ERR(pages);
 
@@ -703,7 +703,7 @@ static void *get_vaddr(struct drm_gem_object *obj, unsigned
madv)
 	if (obj->import_attach)
 		return ERR_PTR(-ENODEV);
 
-	pages = msm_gem_pin_pages_locked(obj, madv);
+	pages = msm_gem_get_pages_locked(obj, madv);
 	if (IS_ERR(pages))
 		return ERR_CAST(pages);
 
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 04/13] drm/msm: Acquire reservation lock in GEM pin/unpin callback

Export msm_gem_pin_pages_locked() and acquire the reservation lock
directly in GEM pin callback. Same for unpin. Prepares for further
changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
msm accordingly by pushing locking out of the implementation. A
follow-up patch will fix locking for all GEM code at once.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/msm/msm_gem.c       | 12 ++++++------
 drivers/gpu/drm/msm/msm_gem.h       |  4 ++--
 drivers/gpu/drm/msm/msm_gem_prime.c | 24 +++++++++++++++++++-----
 3 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index bb729353d3a8d..a5c6498a43f06 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -257,24 +257,24 @@ static void pin_obj_locked(struct drm_gem_object *obj)
 	mutex_unlock(&priv->lru.lock);
 }
 
-struct page **msm_gem_pin_pages(struct drm_gem_object *obj)
+struct page **msm_gem_pin_pages_locked(struct drm_gem_object *obj)
 {
 	struct page **p;
 
-	msm_gem_lock(obj);
+	msm_gem_assert_locked(obj);
+
 	p = msm_gem_get_pages_locked(obj, MSM_MADV_WILLNEED);
 	if (!IS_ERR(p))
 		pin_obj_locked(obj);
-	msm_gem_unlock(obj);
 
 	return p;
 }
 
-void msm_gem_unpin_pages(struct drm_gem_object *obj)
+void msm_gem_unpin_pages_locked(struct drm_gem_object *obj)
 {
-	msm_gem_lock(obj);
+	msm_gem_assert_locked(obj);
+
 	msm_gem_unpin_locked(obj);
-	msm_gem_unlock(obj);
 }
 
 static pgprot_t msm_gem_pgprot(struct msm_gem_object *msm_obj, pgprot_t prot)
diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index 8d414b072c29d..85f0257e83dab 100644
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -140,8 +140,8 @@ int msm_gem_get_and_pin_iova(struct drm_gem_object *obj,
 void msm_gem_unpin_iova(struct drm_gem_object *obj,
 		struct msm_gem_address_space *aspace);
 void msm_gem_pin_obj_locked(struct drm_gem_object *obj);
-struct page **msm_gem_pin_pages(struct drm_gem_object *obj);
-void msm_gem_unpin_pages(struct drm_gem_object *obj);
+struct page **msm_gem_pin_pages_locked(struct drm_gem_object *obj);
+void msm_gem_unpin_pages_locked(struct drm_gem_object *obj);
 int msm_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 		struct drm_mode_create_dumb *args);
 int msm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c
b/drivers/gpu/drm/msm/msm_gem_prime.c
index 0915f3b68752e..0d22df53ab98a 100644
--- a/drivers/gpu/drm/msm/msm_gem_prime.c
+++ b/drivers/gpu/drm/msm/msm_gem_prime.c
@@ -47,13 +47,27 @@ struct drm_gem_object *msm_gem_prime_import_sg_table(struct
drm_device *dev,
 
 int msm_gem_prime_pin(struct drm_gem_object *obj)
 {
-	if (!obj->import_attach)
-		msm_gem_pin_pages(obj);
-	return 0;
+	struct page **pages;
+	int ret = 0;
+
+	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;
 }
 
 void msm_gem_prime_unpin(struct drm_gem_object *obj)
 {
-	if (!obj->import_attach)
-		msm_gem_unpin_pages(obj);
+	if (obj->import_attach)
+		return;
+
+	msm_gem_lock(obj);
+	msm_gem_unpin_pages_locked(obj);
+	msm_gem_unlock(obj);
 }
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 05/13] drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked()

Implement pinning without locking in nouveau_bo_pin_locked(). Keep
nouveau_bo_pin() for acquiring the buffer object's reservation lock.
The new helper will be useful for implementing the GEM pin callback
with correct semantics. Same for unpin.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/nouveau/nouveau_bo.c | 43 +++++++++++++++++++---------
 drivers/gpu/drm/nouveau/nouveau_bo.h |  2 ++
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
b/drivers/gpu/drm/nouveau/nouveau_bo.c
index 56dcd25db1ce2..4a7c002a325a4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -467,17 +467,14 @@ nouveau_bo_placement_set(struct nouveau_bo *nvbo, uint32_t
domain,
 	set_placement_range(nvbo, domain);
 }
 
-int
-nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t domain, bool contig)
+int nouveau_bo_pin_locked(struct nouveau_bo *nvbo, uint32_t domain, bool
contig)
 {
 	struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
 	struct ttm_buffer_object *bo = &nvbo->bo;
 	bool force = false, evict = false;
-	int ret;
+	int ret = 0;
 
-	ret = ttm_bo_reserve(bo, false, false, NULL);
-	if (ret)
-		return ret;
+	dma_resv_assert_held(bo->base.resv);
 
 	if (drm->client.device.info.family >= NV_DEVICE_INFO_V0_TESLA &&
 	    domain == NOUVEAU_GEM_DOMAIN_VRAM && contig) {
@@ -540,20 +537,15 @@ nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t domain,
bool contig)
 out:
 	if (force && ret)
 		nvbo->contig = false;
-	ttm_bo_unreserve(bo);
 	return ret;
 }
 
-int
-nouveau_bo_unpin(struct nouveau_bo *nvbo)
+void nouveau_bo_unpin_locked(struct nouveau_bo *nvbo)
 {
 	struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
 	struct ttm_buffer_object *bo = &nvbo->bo;
-	int ret;
 
-	ret = ttm_bo_reserve(bo, false, false, NULL);
-	if (ret)
-		return ret;
+	dma_resv_assert_held(bo->base.resv);
 
 	ttm_bo_unpin(&nvbo->bo);
 	if (!nvbo->bo.pin_count) {
@@ -568,8 +560,33 @@ nouveau_bo_unpin(struct nouveau_bo *nvbo)
 			break;
 		}
 	}
+}
+
+int nouveau_bo_pin(struct nouveau_bo *nvbo, uint32_t domain, bool contig)
+{
+	struct ttm_buffer_object *bo = &nvbo->bo;
+	int ret;
 
+	ret = ttm_bo_reserve(bo, false, false, NULL);
+	if (ret)
+		return ret;
+	ret = nouveau_bo_pin_locked(nvbo, domain, contig);
+	ttm_bo_unreserve(bo);
+
+	return ret;
+}
+
+int nouveau_bo_unpin(struct nouveau_bo *nvbo)
+{
+	struct ttm_buffer_object *bo = &nvbo->bo;
+	int ret;
+
+	ret = ttm_bo_reserve(bo, false, false, NULL);
+	if (ret)
+		return ret;
+	nouveau_bo_unpin_locked(nvbo);
 	ttm_bo_unreserve(bo);
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.h
b/drivers/gpu/drm/nouveau/nouveau_bo.h
index e9dfab6a81560..4e891752c2551 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.h
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.h
@@ -85,6 +85,8 @@ int  nouveau_bo_new(struct nouveau_cli *, u64 size, int align,
u32 domain,
 		    u32 tile_mode, u32 tile_flags, struct sg_table *sg,
 		    struct dma_resv *robj,
 		    struct nouveau_bo **);
+int  nouveau_bo_pin_locked(struct nouveau_bo *nvbo, uint32_t domain, bool
contig);
+void nouveau_bo_unpin_locked(struct nouveau_bo *nvbo);
 int  nouveau_bo_pin(struct nouveau_bo *, u32 flags, bool contig);
 int  nouveau_bo_unpin(struct nouveau_bo *);
 int  nouveau_bo_map(struct nouveau_bo *);
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 06/13] drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks

Acquire the reservation lock directly in GEM pin callback. Same for
unpin. Prepares for further changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
nouveau accordingly by pushing locking out of the implementation. A
follow-up patch will fix locking for all GEM code at once.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/nouveau/nouveau_prime.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_prime.c
b/drivers/gpu/drm/nouveau/nouveau_prime.c
index 1b2ff0c40fc1c..774f9bd031102 100644
--- a/drivers/gpu/drm/nouveau/nouveau_prime.c
+++ b/drivers/gpu/drm/nouveau/nouveau_prime.c
@@ -86,21 +86,32 @@ struct drm_gem_object
*nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 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;
 
-	/* pin buffer into GTT */
-	ret = nouveau_bo_pin(nvbo, NOUVEAU_GEM_DOMAIN_GART, false);
+	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 0;
+	return ret;
 }
 
 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;
 
-	nouveau_bo_unpin(nvbo);
+	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,
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 07/13] drm/qxl: Provide qxl_bo_{pin,unpin}_locked()

Rename __qxl_bo_pin() to qxl_bo_pin_locked() and update all callers.
The function will be helpful for implementing the GEM pin callback
with correct semantics. Same for __qxl_bo_unpin().

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/qxl/qxl_object.c | 25 +++++++++++++------------
 drivers/gpu/drm/qxl/qxl_object.h |  2 ++
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_object.c b/drivers/gpu/drm/qxl/qxl_object.c
index 1e46b0a6e4787..39218e979a807 100644
--- a/drivers/gpu/drm/qxl/qxl_object.c
+++ b/drivers/gpu/drm/qxl/qxl_object.c
@@ -29,9 +29,6 @@
 #include "qxl_drv.h"
 #include "qxl_object.h"
 
-static int __qxl_bo_pin(struct qxl_bo *bo);
-static void __qxl_bo_unpin(struct qxl_bo *bo);
-
 static void qxl_ttm_bo_destroy(struct ttm_buffer_object *tbo)
 {
 	struct qxl_bo *bo;
@@ -167,13 +164,13 @@ int qxl_bo_vmap_locked(struct qxl_bo *bo, struct iosys_map
*map)
 		goto out;
 	}
 
-	r = __qxl_bo_pin(bo);
+	r = qxl_bo_pin_locked(bo);
 	if (r)
 		return r;
 
 	r = ttm_bo_vmap(&bo->tbo, &bo->map);
 	if (r) {
-		__qxl_bo_unpin(bo);
+		qxl_bo_unpin_locked(bo);
 		return r;
 	}
 	bo->map_count = 1;
@@ -246,7 +243,7 @@ void qxl_bo_vunmap_locked(struct qxl_bo *bo)
 		return;
 	bo->kptr = NULL;
 	ttm_bo_vunmap(&bo->tbo, &bo->map);
-	__qxl_bo_unpin(bo);
+	qxl_bo_unpin_locked(bo);
 }
 
 int qxl_bo_vunmap(struct qxl_bo *bo)
@@ -290,12 +287,14 @@ struct qxl_bo *qxl_bo_ref(struct qxl_bo *bo)
 	return bo;
 }
 
-static int __qxl_bo_pin(struct qxl_bo *bo)
+int qxl_bo_pin_locked(struct qxl_bo *bo)
 {
 	struct ttm_operation_ctx ctx = { false, false };
 	struct drm_device *ddev = bo->tbo.base.dev;
 	int r;
 
+	dma_resv_assert_held(bo->tbo.base.resv);
+
 	if (bo->tbo.pin_count) {
 		ttm_bo_pin(&bo->tbo);
 		return 0;
@@ -309,14 +308,16 @@ static int __qxl_bo_pin(struct qxl_bo *bo)
 	return r;
 }
 
-static void __qxl_bo_unpin(struct qxl_bo *bo)
+void qxl_bo_unpin_locked(struct qxl_bo *bo)
 {
+	dma_resv_assert_held(bo->tbo.base.resv);
+
 	ttm_bo_unpin(&bo->tbo);
 }
 
 /*
  * Reserve the BO before pinning the object.  If the BO was reserved
- * beforehand, use the internal version directly __qxl_bo_pin.
+ * beforehand, use the internal version directly qxl_bo_pin_locked.
  *
  */
 int qxl_bo_pin(struct qxl_bo *bo)
@@ -327,14 +328,14 @@ int qxl_bo_pin(struct qxl_bo *bo)
 	if (r)
 		return r;
 
-	r = __qxl_bo_pin(bo);
+	r = qxl_bo_pin_locked(bo);
 	qxl_bo_unreserve(bo);
 	return r;
 }
 
 /*
  * Reserve the BO before pinning the object.  If the BO was reserved
- * beforehand, use the internal version directly __qxl_bo_unpin.
+ * beforehand, use the internal version directly qxl_bo_unpin_locked.
  *
  */
 int qxl_bo_unpin(struct qxl_bo *bo)
@@ -345,7 +346,7 @@ int qxl_bo_unpin(struct qxl_bo *bo)
 	if (r)
 		return r;
 
-	__qxl_bo_unpin(bo);
+	qxl_bo_unpin_locked(bo);
 	qxl_bo_unreserve(bo);
 	return 0;
 }
diff --git a/drivers/gpu/drm/qxl/qxl_object.h b/drivers/gpu/drm/qxl/qxl_object.h
index 53392cb90eecf..1cf5bc7591016 100644
--- a/drivers/gpu/drm/qxl/qxl_object.h
+++ b/drivers/gpu/drm/qxl/qxl_object.h
@@ -67,6 +67,8 @@ void *qxl_bo_kmap_atomic_page(struct qxl_device *qdev, struct
qxl_bo *bo, int pa
 void qxl_bo_kunmap_atomic_page(struct qxl_device *qdev, struct qxl_bo *bo, void
*map);
 extern struct qxl_bo *qxl_bo_ref(struct qxl_bo *bo);
 extern void qxl_bo_unref(struct qxl_bo **bo);
+extern int qxl_bo_pin_locked(struct qxl_bo *bo);
+extern void qxl_bo_unpin_locked(struct qxl_bo *bo);
 extern int qxl_bo_pin(struct qxl_bo *bo);
 extern int qxl_bo_unpin(struct qxl_bo *bo);
 extern void qxl_ttm_placement_from_domain(struct qxl_bo *qbo, u32 domain);
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 08/13] drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks

Acquire the reservation lock directly in GEM pin callback. Same for
unpin. Prepares for further changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
qxl accordingly by pushing locking out of the implementation. A
follow-up patch will fix locking for all GEM code at once.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/qxl/qxl_prime.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_prime.c b/drivers/gpu/drm/qxl/qxl_prime.c
index 9169c26357d36..f2646603e12eb 100644
--- a/drivers/gpu/drm/qxl/qxl_prime.c
+++ b/drivers/gpu/drm/qxl/qxl_prime.c
@@ -31,15 +31,27 @@
 int qxl_gem_prime_pin(struct drm_gem_object *obj)
 {
 	struct qxl_bo *bo = gem_to_qxl_bo(obj);
+	int r;
 
-	return qxl_bo_pin(bo);
+	r = qxl_bo_reserve(bo);
+	if (r)
+		return r;
+	r = qxl_bo_pin_locked(bo);
+	qxl_bo_unreserve(bo);
+
+	return r;
 }
 
 void qxl_gem_prime_unpin(struct drm_gem_object *obj)
 {
 	struct qxl_bo *bo = gem_to_qxl_bo(obj);
+	int r;
 
-	qxl_bo_unpin(bo);
+	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)
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 09/13] 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 at suse.de>
---
 drivers/gpu/drm/drm_gem.c               | 22 ++++++++++++++++++++--
 drivers/gpu/drm/drm_gem_vram_helper.c   | 15 +--------------
 drivers/gpu/drm/drm_internal.h          |  2 ++
 drivers/gpu/drm/loongson/lsdc_gem.c     | 13 ++-----------
 drivers/gpu/drm/msm/msm_gem_prime.c     |  4 ----
 drivers/gpu/drm/nouveau/nouveau_prime.c | 11 -----------
 drivers/gpu/drm/qxl/qxl_prime.c         | 14 +-------------
 drivers/gpu/drm/radeon/radeon_prime.c   | 11 -----------
 drivers/gpu/drm/vmwgfx/vmwgfx_gem.c     | 25 ++++++-------------------
 include/drm/drm_gem_shmem_helper.h      | 11 +----------
 10 files changed, 33 insertions(+), 95 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 44a948b80ee14..e0f80c6a7096f 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 15029d89badf8..5a16b3e0a4134 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 8e4faf0a28e6c..40b2d3a274d6c 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -170,6 +170,8 @@ 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 04293df2f0de0..a720d8f532093 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 0d22df53ab98a..ee267490c9359 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 774f9bd031102..b58ab595faf82 100644
--- a/drivers/gpu/drm/nouveau/nouveau_prime.c
+++ b/drivers/gpu/drm/nouveau/nouveau_prime.c
@@ -86,17 +86,12 @@ struct drm_gem_object
*nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 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 f2646603e12eb..19bf551a7b311 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 b3cfc99f4d7ed..a77881f035e7a 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 12787bb9c111d..186150f41fbcc 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 eb12aa9a8c556..efbc9f27312b5 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);
 }
 
 /**
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 10/13] drm/fbdev-generic: Fix locking with drm_client_buffer_vmap_local()

Temporarily lock the fbdev buffer object during updates to prevent
memory managers from evicting/moving the buffer. Moving a buffer
object while update its content results in undefined behaviour.

Fbdev-generic updates its buffer object from a shadow buffer. Gem-shmem
and gem-dma helpers do not move buffer objects, so they are safe to be
used with fbdev-generic. Gem-vram and qxl are based on TTM, but pin
buffer objects are part of the vmap operation. So both are also safe
to be used with fbdev-generic.

Amdgpu and nouveau do not pin or lock the buffer object during an
update. Their TTM-based memory management could move the buffer object
while the update is ongoing.

The new vmap_local and vunmap_local helpers hold the buffer object's
reservation lock during the buffer update. This prevents moving the
buffer object on all memory managers.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/drm_client.c        | 68 +++++++++++++++++++++++++----
 drivers/gpu/drm/drm_fbdev_generic.c |  4 +-
 drivers/gpu/drm/drm_gem.c           | 12 +++++
 include/drm/drm_client.h            | 10 +++++
 include/drm/drm_gem.h               |  3 ++
 5 files changed, 87 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 9403b3f576f7b..2cc81831236b5 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -304,6 +304,66 @@ drm_client_buffer_create(struct drm_client_dev *client, u32
width, u32 height,
 	return ERR_PTR(ret);
 }
 
+/**
+ * drm_client_buffer_vmap_local - Map DRM client buffer into address space
+ * @buffer: DRM client buffer
+ * @map_copy: Returns the mapped memory's address
+ *
+ * This function maps a client buffer into kernel address space. If the
+ * buffer is already mapped, it returns the existing mapping's address.
+ *
+ * Client buffer mappings are not ref'counted. Each call to
+ * drm_client_buffer_vmap_local() should be closely followed by a call to
+ * drm_client_buffer_vunmap_local(). See drm_client_buffer_vmap() for
+ * long-term mappings.
+ *
+ * The returned address is a copy of the internal value. In contrast to
+ * other vmap interfaces, you don't need it for the client's vunmap
+ * function. So you can modify it at will during blit and draw operations.
+ *
+ * Returns:
+ *	0 on success, or a negative errno code otherwise.
+ */
+int drm_client_buffer_vmap_local(struct drm_client_buffer *buffer,
+				 struct iosys_map *map_copy)
+{
+	struct drm_gem_object *gem = buffer->gem;
+	struct iosys_map *map = &buffer->map;
+	int ret;
+
+	drm_gem_lock(gem);
+
+	ret = drm_gem_vmap(gem, map);
+	if (ret)
+		goto err_drm_gem_vmap_unlocked;
+	*map_copy = *map;
+
+	return 0;
+
+err_drm_gem_vmap_unlocked:
+	drm_gem_unlock(gem);
+	return 0;
+}
+EXPORT_SYMBOL(drm_client_buffer_vmap_local);
+
+/**
+ * drm_client_buffer_vunmap_local - Unmap DRM client buffer
+ * @buffer: DRM client buffer
+ *
+ * This function removes a client buffer's memory mapping established
+ * with drm_client_buffer_vunmap_local(). Calling this function is only
+ * required by clients that manage their buffer mappings by themselves.
+ */
+void drm_client_buffer_vunmap_local(struct drm_client_buffer *buffer)
+{
+	struct drm_gem_object *gem = buffer->gem;
+	struct iosys_map *map = &buffer->map;
+
+	drm_gem_vunmap(gem, map);
+	drm_gem_unlock(gem);
+}
+EXPORT_SYMBOL(drm_client_buffer_vunmap_local);
+
 /**
  * drm_client_buffer_vmap - Map DRM client buffer into address space
  * @buffer: DRM client buffer
@@ -331,14 +391,6 @@ drm_client_buffer_vmap(struct drm_client_buffer *buffer,
 	struct iosys_map *map = &buffer->map;
 	int ret;
 
-	/*
-	 * FIXME: The dependency on GEM here isn't required, we could
-	 * convert the driver handle to a dma-buf instead and use the
-	 * backend-agnostic dma-buf vmap support instead. This would
-	 * require that the handle2fd prime ioctl is reworked to pull the
-	 * fd_install step out of the driver backend hooks, to make that
-	 * final step optional for internal users.
-	 */
 	ret = drm_gem_vmap_unlocked(buffer->gem, map);
 	if (ret)
 		return ret;
diff --git a/drivers/gpu/drm/drm_fbdev_generic.c
b/drivers/gpu/drm/drm_fbdev_generic.c
index d647d89764cb9..be357f926faec 100644
--- a/drivers/gpu/drm/drm_fbdev_generic.c
+++ b/drivers/gpu/drm/drm_fbdev_generic.c
@@ -197,14 +197,14 @@ static int drm_fbdev_generic_damage_blit(struct
drm_fb_helper *fb_helper,
 	 */
 	mutex_lock(&fb_helper->lock);
 
-	ret = drm_client_buffer_vmap(buffer, &map);
+	ret = drm_client_buffer_vmap_local(buffer, &map);
 	if (ret)
 		goto out;
 
 	dst = map;
 	drm_fbdev_generic_damage_blit_real(fb_helper, clip, &dst);
 
-	drm_client_buffer_vunmap(buffer);
+	drm_client_buffer_vunmap_local(buffer);
 
 out:
 	mutex_unlock(&fb_helper->lock);
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index e0f80c6a7096f..d4bbc5d109c8b 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1227,6 +1227,18 @@ void drm_gem_vunmap(struct drm_gem_object *obj, struct
iosys_map *map)
 }
 EXPORT_SYMBOL(drm_gem_vunmap);
 
+void drm_gem_lock(struct drm_gem_object *obj)
+{
+	dma_resv_lock(obj->resv, NULL);
+}
+EXPORT_SYMBOL(drm_gem_lock);
+
+void drm_gem_unlock(struct drm_gem_object *obj)
+{
+	dma_resv_unlock(obj->resv);
+}
+EXPORT_SYMBOL(drm_gem_unlock);
+
 int drm_gem_vmap_unlocked(struct drm_gem_object *obj, struct iosys_map *map)
 {
 	int ret;
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index d47458ecdac46..bc0e66f9c4251 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -141,6 +141,13 @@ struct drm_client_buffer {
 
 	/**
 	 * @gem: GEM object backing this buffer
+	 *
+	 * FIXME: The dependency on GEM here isn't required, we could
+	 * convert the driver handle to a dma-buf instead and use the
+	 * backend-agnostic dma-buf vmap support instead. This would
+	 * require that the handle2fd prime ioctl is reworked to pull the
+	 * fd_install step out of the driver backend hooks, to make that
+	 * final step optional for internal users.
 	 */
 	struct drm_gem_object *gem;
 
@@ -159,6 +166,9 @@ struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32
height, u32 format);
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
 int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct
drm_rect *rect);
+int drm_client_buffer_vmap_local(struct drm_client_buffer *buffer,
+				 struct iosys_map *map_copy);
+void drm_client_buffer_vunmap_local(struct drm_client_buffer *buffer);
 int drm_client_buffer_vmap(struct drm_client_buffer *buffer,
 			   struct iosys_map *map);
 void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 2ebec3984cd44..bae4865b2101a 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -527,6 +527,9 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj);
 void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
 		bool dirty, bool accessed);
 
+void drm_gem_lock(struct drm_gem_object *obj);
+void drm_gem_unlock(struct drm_gem_object *obj);
+
 int drm_gem_vmap_unlocked(struct drm_gem_object *obj, struct iosys_map *map);
 void drm_gem_vunmap_unlocked(struct drm_gem_object *obj, struct iosys_map
*map);
 
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 11/13] drm/client: Pin vmap'ed GEM buffers

The function drm_client_buffer_vmap() establishes a long-term mapping
of the client's buffer object into the kernel address space. Make sure
that buffer does not move by pinning it to its current location. Same
for vunmap with unpin.

The only caller of drm_client_buffer_vmap() is fbdev-dma, which uses
gem-dma. As DMA-backed GEM buffers do not move, this change is for
correctness with little impact in practice.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/drm_client.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 2cc81831236b5..77fe217aeaf36 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -388,16 +388,30 @@ int
 drm_client_buffer_vmap(struct drm_client_buffer *buffer,
 		       struct iosys_map *map_copy)
 {
+	struct drm_gem_object *gem = buffer->gem;
 	struct iosys_map *map = &buffer->map;
 	int ret;
 
-	ret = drm_gem_vmap_unlocked(buffer->gem, map);
+	drm_gem_lock(gem);
+
+	ret = drm_gem_pin_locked(gem);
 	if (ret)
-		return ret;
+		goto err_drm_gem_pin_locked;
+	ret = drm_gem_vmap(gem, map);
+	if (ret)
+		goto err_drm_gem_vmap;
+
+	drm_gem_unlock(gem);
 
 	*map_copy = *map;
 
 	return 0;
+
+err_drm_gem_vmap:
+	drm_gem_unpin_locked(buffer->gem);
+err_drm_gem_pin_locked:
+	drm_gem_unlock(gem);
+	return ret;
 }
 EXPORT_SYMBOL(drm_client_buffer_vmap);
 
@@ -411,9 +425,13 @@ EXPORT_SYMBOL(drm_client_buffer_vmap);
  */
 void drm_client_buffer_vunmap(struct drm_client_buffer *buffer)
 {
+	struct drm_gem_object *gem = buffer->gem;
 	struct iosys_map *map = &buffer->map;
 
-	drm_gem_vunmap_unlocked(buffer->gem, map);
+	drm_gem_lock(gem);
+	drm_gem_vunmap(gem, map);
+	drm_gem_unpin_locked(gem);
+	drm_gem_unlock(gem);
 }
 EXPORT_SYMBOL(drm_client_buffer_vunmap);
 
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:14 UTC

head link

[PATCH 12/13] drm/gem-vram: Do not pin buffer objects for vmap

Pin and vmap are distinct operations. Do not perform a pin as part
of the vmap call. This used to be necessary to keep the fbdev buffer
in place while it is being updated. Fbdev emulation has meanwhile
been fixed to lock the buffer correctly. Same for vunmap.

For refactoring the code, remove the pin calls from the helper's
vmap implementation in drm_gem_vram_vmap() and inline the call to
drm_gem_vram_kmap_locked(). This gives a vmap helper that only
maps the buffer object's memory pages without pinning or locking.
Do a similar refactoring for vunmap.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/drm_gem_vram_helper.c | 90 ++++++++++-----------------
 1 file changed, 32 insertions(+), 58 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c
b/drivers/gpu/drm/drm_gem_vram_helper.c
index 5a16b3e0a4134..45650b9b3de91 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -368,11 +368,28 @@ int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo)
 }
 EXPORT_SYMBOL(drm_gem_vram_unpin);
 
-static int drm_gem_vram_kmap_locked(struct drm_gem_vram_object *gbo,
-				    struct iosys_map *map)
+/**
+ * drm_gem_vram_vmap() - Pins and maps a GEM VRAM object into kernel address
+ *                       space
+ * @gbo: The GEM VRAM object to map
+ * @map: Returns the kernel virtual address of the VRAM GEM object's
backing
+ *       store.
+ *
+ * The vmap function pins a GEM VRAM object to its current location, either
+ * system or video memory, and maps its buffer into kernel address space.
+ * As pinned object cannot be relocated, you should avoid pinning objects
+ * permanently. Call drm_gem_vram_vunmap() with the returned address to
+ * unmap and unpin the GEM VRAM object.
+ *
+ * Returns:
+ * 0 on success, or a negative error code otherwise.
+ */
+int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct iosys_map *map)
 {
 	int ret;
 
+	dma_resv_assert_held(gbo->bo.base.resv);
+
 	if (gbo->vmap_use_count > 0)
 		goto out;
 
@@ -393,12 +410,23 @@ static int drm_gem_vram_kmap_locked(struct
drm_gem_vram_object *gbo,
 
 	return 0;
 }
+EXPORT_SYMBOL(drm_gem_vram_vmap);
 
-static void drm_gem_vram_kunmap_locked(struct drm_gem_vram_object *gbo,
-				       struct iosys_map *map)
+/**
+ * drm_gem_vram_vunmap() - Unmaps and unpins a GEM VRAM object
+ * @gbo: The GEM VRAM object to unmap
+ * @map: Kernel virtual address where the VRAM GEM object was mapped
+ *
+ * A call to drm_gem_vram_vunmap() unmaps and unpins a GEM VRAM buffer. See
+ * the documentation for drm_gem_vram_vmap() for more information.
+ */
+void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo,
+			 struct iosys_map *map)
 {
 	struct drm_device *dev = gbo->bo.base.dev;
 
+	dma_resv_assert_held(gbo->bo.base.resv);
+
 	if (drm_WARN_ON_ONCE(dev, !gbo->vmap_use_count))
 		return;
 
@@ -415,60 +443,6 @@ static void drm_gem_vram_kunmap_locked(struct
drm_gem_vram_object *gbo,
 	 * from memory. See drm_gem_vram_bo_driver_move_notify().
 	 */
 }
-
-/**
- * drm_gem_vram_vmap() - Pins and maps a GEM VRAM object into kernel address
- *                       space
- * @gbo: The GEM VRAM object to map
- * @map: Returns the kernel virtual address of the VRAM GEM object's
backing
- *       store.
- *
- * The vmap function pins a GEM VRAM object to its current location, either
- * system or video memory, and maps its buffer into kernel address space.
- * As pinned object cannot be relocated, you should avoid pinning objects
- * permanently. Call drm_gem_vram_vunmap() with the returned address to
- * unmap and unpin the GEM VRAM object.
- *
- * Returns:
- * 0 on success, or a negative error code otherwise.
- */
-int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct iosys_map *map)
-{
-	int ret;
-
-	dma_resv_assert_held(gbo->bo.base.resv);
-
-	ret = drm_gem_vram_pin_locked(gbo, 0);
-	if (ret)
-		return ret;
-	ret = drm_gem_vram_kmap_locked(gbo, map);
-	if (ret)
-		goto err_drm_gem_vram_unpin_locked;
-
-	return 0;
-
-err_drm_gem_vram_unpin_locked:
-	drm_gem_vram_unpin_locked(gbo);
-	return ret;
-}
-EXPORT_SYMBOL(drm_gem_vram_vmap);
-
-/**
- * drm_gem_vram_vunmap() - Unmaps and unpins a GEM VRAM object
- * @gbo: The GEM VRAM object to unmap
- * @map: Kernel virtual address where the VRAM GEM object was mapped
- *
- * A call to drm_gem_vram_vunmap() unmaps and unpins a GEM VRAM buffer. See
- * the documentation for drm_gem_vram_vmap() for more information.
- */
-void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo,
-			 struct iosys_map *map)
-{
-	dma_resv_assert_held(gbo->bo.base.resv);
-
-	drm_gem_vram_kunmap_locked(gbo, map);
-	drm_gem_vram_unpin_locked(gbo);
-}
 EXPORT_SYMBOL(drm_gem_vram_vunmap);
 
 /**
-- 
2.43.2

Thomas Zimmermann

2024-Feb-27 10:15 UTC

head link

[PATCH 13/13] drm/qxl: Do not pin buffer objects for vmap

Pin and vmap are distinct operations. Do not perform a pin as part
of the vmap call. This used to be necessary to keep the fbdev buffer
in place while it is being updated. Fbdev emulation has meanwhile
been fixed to lock the buffer correctly. Same for vunmap.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/qxl/qxl_object.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_object.c b/drivers/gpu/drm/qxl/qxl_object.c
index 39218e979a807..5893e27a7ae50 100644
--- a/drivers/gpu/drm/qxl/qxl_object.c
+++ b/drivers/gpu/drm/qxl/qxl_object.c
@@ -164,10 +164,6 @@ int qxl_bo_vmap_locked(struct qxl_bo *bo, struct iosys_map
*map)
 		goto out;
 	}
 
-	r = qxl_bo_pin_locked(bo);
-	if (r)
-		return r;
-
 	r = ttm_bo_vmap(&bo->tbo, &bo->map);
 	if (r) {
 		qxl_bo_unpin_locked(bo);
@@ -243,7 +239,6 @@ void qxl_bo_vunmap_locked(struct qxl_bo *bo)
 		return;
 	bo->kptr = NULL;
 	ttm_bo_vunmap(&bo->tbo, &bo->map);
-	qxl_bo_unpin_locked(bo);
 }
 
 int qxl_bo_vunmap(struct qxl_bo *bo)
-- 
2.43.2

Christian König

2024-Feb-27 14:03 UTC

head link

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

Nice, looks totally valid to me.

Feel free to add to patch #2, #9, #10, #11 and #12 Reviewed-by: 
Christian K?nig <christian.koenig at amd.com>

And Acked-by: Christian K?nig <christian.koenig at amd.com> to the rest.

Regards,
Christian.

Am 27.02.24 um 11:14 schrieb Thomas Zimmermann:> Dma-buf locking semantics require the caller of pin and unpin to hold
> the buffer's reservation lock. Fix DRM to adhere to the specs. This
> enables to fix the locking in DRM's console emulation. Similar changes
> for vmap and mmap have been posted at [1][2]
>
> Most DRM drivers and memory managers acquire the buffer object's
> reservation lock within their GEM pin and unpin callbacks. This
> violates dma-buf locking semantics. We get away with it because PRIME
> does not provide pin/unpin, but attach/detach, for which the locking
> semantics is correct.
>
> Patches 1 to 8 rework DRM GEM code in various implementations to
> acquire the reservation lock when entering the pin and unpin callbacks.
> This prepares them for the next patch. Drivers that are not affected
> by these patches either don't acquire the reservation lock (amdgpu)
> or don't need preparation (loongson).
>
> Patch 9 moves reservation locking from the GEM pin/unpin callbacks
> into drm_gem_pin() and drm_gem_unpin(). As PRIME uses these functions
> internally it still gets the reservation lock.
>
> With the updated GEM callbacks, the rest of the patchset fixes the
> fbdev emulation's buffer locking. Fbdev emulation needs to keep its
> GEM buffer object inplace while updating its content. This required
> a implicit pinning and apparently amdgpu didn't do this at all.
>
> Patch 10 introduces drm_client_buffer_vmap_local() and _vunmap_local().
> The former function map a GEM buffer into the kernel's address space
> with regular vmap operations, but keeps holding the reservation lock.
> The _vunmap_local() helper undoes the vmap and releases the lock. The
> updated GEM callbacks make this possible. Between the two calls, the
> fbdev emulation can update the buffer content without have the buffer
> moved or evicted. Update fbdev-generic to use vmap_local helpers,
> which fix amdgpu. The idea of adding a "local vmap" has
previously been
> attempted at [3] in a different form.
>
> Patch 11 adds implicit pinning to the DRM client's regular vmap
> helper so that long-term vmap'ed buffers won't be evicted. This
only
> affects fbdev-dma, but GEM DMA helpers don't require pinning. So
> there are no practical changes.
>
> Patches 12 and 13 remove implicit pinning from the vmap and vunmap
> operations in gem-vram and qxl. These pin operations are not supposed
> to be part of vmap code, but were required to keep the buffers in place
> for fbdev emulation. With the conversion o ffbdev-generic to to
> vmap_local helpers, that code can finally be removed.
>
> Tested with amdgpu, nouveau, radeon, simpledrm and vc4.
>
> [1] https://patchwork.freedesktop.org/series/106371/
> [2] https://patchwork.freedesktop.org/series/116001/
> [3] https://patchwork.freedesktop.org/series/84732/
>
> Thomas Zimmermann (13):
>    drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks
>    drm/gem-vram: Acquire reservation lock in GEM pin/unpin callbacks
>    drm/msm: Provide msm_gem_get_pages_locked()
>    drm/msm: Acquire reservation lock in GEM pin/unpin callback
>    drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked()
>    drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks
>    drm/qxl: Provide qxl_bo_{pin,unpin}_locked()
>    drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks
>    drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}()
>    drm/fbdev-generic: Fix locking with drm_client_buffer_vmap_local()
>    drm/client: Pin vmap'ed GEM buffers
>    drm/gem-vram: Do not pin buffer objects for vmap
>    drm/qxl: Do not pin buffer objects for vmap
>
>   drivers/gpu/drm/drm_client.c            |  92 ++++++++++++++++++---
>   drivers/gpu/drm/drm_fbdev_generic.c     |   4 +-
>   drivers/gpu/drm/drm_gem.c               |  34 +++++++-
>   drivers/gpu/drm/drm_gem_shmem_helper.c  |   6 +-
>   drivers/gpu/drm/drm_gem_vram_helper.c   | 101 ++++++++++--------------
>   drivers/gpu/drm/drm_internal.h          |   2 +
>   drivers/gpu/drm/loongson/lsdc_gem.c     |  13 +--
>   drivers/gpu/drm/msm/msm_gem.c           |  20 ++---
>   drivers/gpu/drm/msm/msm_gem.h           |   4 +-
>   drivers/gpu/drm/msm/msm_gem_prime.c     |  20 +++--
>   drivers/gpu/drm/nouveau/nouveau_bo.c    |  43 +++++++---
>   drivers/gpu/drm/nouveau/nouveau_bo.h    |   2 +
>   drivers/gpu/drm/nouveau/nouveau_prime.c |   8 +-
>   drivers/gpu/drm/qxl/qxl_object.c        |  26 +++---
>   drivers/gpu/drm/qxl/qxl_object.h        |   2 +
>   drivers/gpu/drm/qxl/qxl_prime.c         |   4 +-
>   drivers/gpu/drm/radeon/radeon_prime.c   |  11 ---
>   drivers/gpu/drm/vmwgfx/vmwgfx_gem.c     |  25 ++----
>   include/drm/drm_client.h                |  10 +++
>   include/drm/drm_gem.h                   |   3 +
>   include/drm/drm_gem_shmem_helper.h      |   7 +-
>   21 files changed, 265 insertions(+), 172 deletions(-)
>
>
> base-commit: 7291e2e67dff0ff573900266382c9c9248a7dea5
> prerequisite-patch-id: bdfa0e6341b30cc9d7647172760b3473007c1216
> prerequisite-patch-id: bc27ac702099f481890ae2c7c4a9c531f4a62d64
> prerequisite-patch-id: f5d4bf16dc45334254527c2e31ee21ba4582761c
> prerequisite-patch-id: 734c87e610747779aa41be12eb9e4c984bdfa743
> prerequisite-patch-id: 0aa359f6144c4015c140c8a6750be19099c676fb
> prerequisite-patch-id: c67e5d886a47b7d0266d81100837557fda34cb24
> prerequisite-patch-id: cbc453ee02fae02af22fbfdce56ab732c7a88c36

Dmitry Osipenko

2024-Feb-27 18:14 UTC

head link

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

Hello,

Thank you for the patches!

On 2/27/24 13:14, Thomas Zimmermann wrote:> Dma-buf locking semantics require the caller of pin and unpin to hold
> the buffer's reservation lock. Fix DRM to adhere to the specs. This
> enables to fix the locking in DRM's console emulation. Similar changes
> for vmap and mmap have been posted at [1][2]
> 
> Most DRM drivers and memory managers acquire the buffer object's
> reservation lock within their GEM pin and unpin callbacks. This
> violates dma-buf locking semantics. We get away with it because PRIME
> does not provide pin/unpin, but attach/detach, for which the locking
> semantics is correct.
> 
> Patches 1 to 8 rework DRM GEM code in various implementations to
> acquire the reservation lock when entering the pin and unpin callbacks.
> This prepares them for the next patch. Drivers that are not affected
> by these patches either don't acquire the reservation lock (amdgpu)
> or don't need preparation (loongson).
> 
> Patch 9 moves reservation locking from the GEM pin/unpin callbacks
> into drm_gem_pin() and drm_gem_unpin(). As PRIME uses these functions
> internally it still gets the reservation lock.
> 
> With the updated GEM callbacks, the rest of the patchset fixes the
> fbdev emulation's buffer locking. Fbdev emulation needs to keep its
> GEM buffer object inplace while updating its content. This required
> a implicit pinning and apparently amdgpu didn't do this at all.
> 
> Patch 10 introduces drm_client_buffer_vmap_local() and _vunmap_local().
> The former function map a GEM buffer into the kernel's address space
> with regular vmap operations, but keeps holding the reservation lock.
> The _vunmap_local() helper undoes the vmap and releases the lock. The
> updated GEM callbacks make this possible. Between the two calls, the
> fbdev emulation can update the buffer content without have the buffer
> moved or evicted. Update fbdev-generic to use vmap_local helpers,
> which fix amdgpu. The idea of adding a "local vmap" has
previously been
> attempted at [3] in a different form.
> 
> Patch 11 adds implicit pinning to the DRM client's regular vmap
> helper so that long-term vmap'ed buffers won't be evicted. This
only
> affects fbdev-dma, but GEM DMA helpers don't require pinning. So
> there are no practical changes.
> 
> Patches 12 and 13 remove implicit pinning from the vmap and vunmap
> operations in gem-vram and qxl. These pin operations are not supposed
> to be part of vmap code, but were required to keep the buffers in place
> for fbdev emulation. With the conversion o ffbdev-generic to to
> vmap_local helpers, that code can finally be removed.
Isn't it a common behaviour for all DRM drivers to implicitly pin BO
while it's vmapped? I was sure it should be common /o\

Why would you want to kmap BO that isn't pinned?

Shouldn't TTM's vmap() be changed to do the pinning?

I missed that TTM doesn't pin BO on vmap() and now surprised to see it.
It should be a rather serious problem requiring backporting of the
fixes, but I don't see the fixes tags on the patches (?)

-- 
Best regards,
Dmitry

Zack Rusin

2024-Feb-28 03:54 UTC

head link

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

On Tue, Feb 27, 2024 at 6:38?AM Thomas Zimmermann <tzimmermann at suse.de>
wrote:>
> Dma-buf locking semantics require the caller of pin and unpin to hold
> the buffer's reservation lock. Fix DRM to adhere to the specs. This
> enables to fix the locking in DRM's console emulation. Similar changes
> for vmap and mmap have been posted at [1][2]
>
> Most DRM drivers and memory managers acquire the buffer object's
> reservation lock within their GEM pin and unpin callbacks. This
> violates dma-buf locking semantics. We get away with it because PRIME
> does not provide pin/unpin, but attach/detach, for which the locking
> semantics is correct.
>
> Patches 1 to 8 rework DRM GEM code in various implementations to
> acquire the reservation lock when entering the pin and unpin callbacks.
> This prepares them for the next patch. Drivers that are not affected
> by these patches either don't acquire the reservation lock (amdgpu)
> or don't need preparation (loongson).
>
> Patch 9 moves reservation locking from the GEM pin/unpin callbacks
> into drm_gem_pin() and drm_gem_unpin(). As PRIME uses these functions
> internally it still gets the reservation lock.
>
> With the updated GEM callbacks, the rest of the patchset fixes the
> fbdev emulation's buffer locking. Fbdev emulation needs to keep its
> GEM buffer object inplace while updating its content. This required
> a implicit pinning and apparently amdgpu didn't do this at all.
>
> Patch 10 introduces drm_client_buffer_vmap_local() and _vunmap_local().
> The former function map a GEM buffer into the kernel's address space
> with regular vmap operations, but keeps holding the reservation lock.
> The _vunmap_local() helper undoes the vmap and releases the lock. The
> updated GEM callbacks make this possible. Between the two calls, the
> fbdev emulation can update the buffer content without have the buffer
> moved or evicted. Update fbdev-generic to use vmap_local helpers,
> which fix amdgpu. The idea of adding a "local vmap" has
previously been
> attempted at [3] in a different form.
>
> Patch 11 adds implicit pinning to the DRM client's regular vmap
> helper so that long-term vmap'ed buffers won't be evicted. This
only
> affects fbdev-dma, but GEM DMA helpers don't require pinning. So
> there are no practical changes.
>
> Patches 12 and 13 remove implicit pinning from the vmap and vunmap
> operations in gem-vram and qxl. These pin operations are not supposed
> to be part of vmap code, but were required to keep the buffers in place
> for fbdev emulation. With the conversion o ffbdev-generic to to
> vmap_local helpers, that code can finally be removed.
>
> Tested with amdgpu, nouveau, radeon, simpledrm and vc4.
>
> [1] https://patchwork.freedesktop.org/series/106371/
> [2] https://patchwork.freedesktop.org/series/116001/
> [3] https://patchwork.freedesktop.org/series/84732/
>
> Thomas Zimmermann (13):
>   drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/gem-vram: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/msm: Provide msm_gem_get_pages_locked()
>   drm/msm: Acquire reservation lock in GEM pin/unpin callback
>   drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked()
>   drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/qxl: Provide qxl_bo_{pin,unpin}_locked()
>   drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}()
>   drm/fbdev-generic: Fix locking with drm_client_buffer_vmap_local()
>   drm/client: Pin vmap'ed GEM buffers
>   drm/gem-vram: Do not pin buffer objects for vmap
>   drm/qxl: Do not pin buffer objects for vmap
>
>  drivers/gpu/drm/drm_client.c            |  92 ++++++++++++++++++---
>  drivers/gpu/drm/drm_fbdev_generic.c     |   4 +-
>  drivers/gpu/drm/drm_gem.c               |  34 +++++++-
>  drivers/gpu/drm/drm_gem_shmem_helper.c  |   6 +-
>  drivers/gpu/drm/drm_gem_vram_helper.c   | 101 ++++++++++--------------
>  drivers/gpu/drm/drm_internal.h          |   2 +
>  drivers/gpu/drm/loongson/lsdc_gem.c     |  13 +--
>  drivers/gpu/drm/msm/msm_gem.c           |  20 ++---
>  drivers/gpu/drm/msm/msm_gem.h           |   4 +-
>  drivers/gpu/drm/msm/msm_gem_prime.c     |  20 +++--
>  drivers/gpu/drm/nouveau/nouveau_bo.c    |  43 +++++++---
>  drivers/gpu/drm/nouveau/nouveau_bo.h    |   2 +
>  drivers/gpu/drm/nouveau/nouveau_prime.c |   8 +-
>  drivers/gpu/drm/qxl/qxl_object.c        |  26 +++---
>  drivers/gpu/drm/qxl/qxl_object.h        |   2 +
>  drivers/gpu/drm/qxl/qxl_prime.c         |   4 +-
>  drivers/gpu/drm/radeon/radeon_prime.c   |  11 ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_gem.c     |  25 ++----
>  include/drm/drm_client.h                |  10 +++
>  include/drm/drm_gem.h                   |   3 +
>  include/drm/drm_gem_shmem_helper.h      |   7 +-
>  21 files changed, 265 insertions(+), 172 deletions(-)
>
>
> base-commit: 7291e2e67dff0ff573900266382c9c9248a7dea5
> prerequisite-patch-id: bdfa0e6341b30cc9d7647172760b3473007c1216
> prerequisite-patch-id: bc27ac702099f481890ae2c7c4a9c531f4a62d64
> prerequisite-patch-id: f5d4bf16dc45334254527c2e31ee21ba4582761c
> prerequisite-patch-id: 734c87e610747779aa41be12eb9e4c984bdfa743
> prerequisite-patch-id: 0aa359f6144c4015c140c8a6750be19099c676fb
> prerequisite-patch-id: c67e5d886a47b7d0266d81100837557fda34cb24
> prerequisite-patch-id: cbc453ee02fae02af22fbfdce56ab732c7a88c36
> --
> 2.43.2
>
That's a really nice cleanup! I already gave a r-b for 9/13. For the rest:
Acked-by: Zack Rusin <zack.rusin at broadcom.com>

z

Dmitry Osipenko

2024-Mar-05 21:58 UTC

head link

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

On 2/27/24 13:14, Thomas Zimmermann wrote:> Dma-buf locking semantics require the caller of pin and unpin to hold
> the buffer's reservation lock. Fix DRM to adhere to the specs. This
> enables to fix the locking in DRM's console emulation. Similar changes
> for vmap and mmap have been posted at [1][2]
> 
> Most DRM drivers and memory managers acquire the buffer object's
> reservation lock within their GEM pin and unpin callbacks. This
> violates dma-buf locking semantics. We get away with it because PRIME
> does not provide pin/unpin, but attach/detach, for which the locking
> semantics is correct.
> 
> Patches 1 to 8 rework DRM GEM code in various implementations to
> acquire the reservation lock when entering the pin and unpin callbacks.
> This prepares them for the next patch. Drivers that are not affected
> by these patches either don't acquire the reservation lock (amdgpu)
> or don't need preparation (loongson).
> 
> Patch 9 moves reservation locking from the GEM pin/unpin callbacks
> into drm_gem_pin() and drm_gem_unpin(). As PRIME uses these functions
> internally it still gets the reservation lock.
> 
> With the updated GEM callbacks, the rest of the patchset fixes the
> fbdev emulation's buffer locking. Fbdev emulation needs to keep its
> GEM buffer object inplace while updating its content. This required
> a implicit pinning and apparently amdgpu didn't do this at all.
> 
> Patch 10 introduces drm_client_buffer_vmap_local() and _vunmap_local().
> The former function map a GEM buffer into the kernel's address space
> with regular vmap operations, but keeps holding the reservation lock.
> The _vunmap_local() helper undoes the vmap and releases the lock. The
> updated GEM callbacks make this possible. Between the two calls, the
> fbdev emulation can update the buffer content without have the buffer
> moved or evicted. Update fbdev-generic to use vmap_local helpers,
> which fix amdgpu. The idea of adding a "local vmap" has
previously been
> attempted at [3] in a different form.
> 
> Patch 11 adds implicit pinning to the DRM client's regular vmap
> helper so that long-term vmap'ed buffers won't be evicted. This
only
> affects fbdev-dma, but GEM DMA helpers don't require pinning. So
> there are no practical changes.
> 
> Patches 12 and 13 remove implicit pinning from the vmap and vunmap
> operations in gem-vram and qxl. These pin operations are not supposed
> to be part of vmap code, but were required to keep the buffers in place
> for fbdev emulation. With the conversion o ffbdev-generic to to
> vmap_local helpers, that code can finally be removed.
> 
> Tested with amdgpu, nouveau, radeon, simpledrm and vc4.
> 
> [1] https://patchwork.freedesktop.org/series/106371/
> [2] https://patchwork.freedesktop.org/series/116001/
> [3] https://patchwork.freedesktop.org/series/84732/
> 
> Thomas Zimmermann (13):
>   drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/gem-vram: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/msm: Provide msm_gem_get_pages_locked()
>   drm/msm: Acquire reservation lock in GEM pin/unpin callback
>   drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked()
>   drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/qxl: Provide qxl_bo_{pin,unpin}_locked()
>   drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks
>   drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}()
>   drm/fbdev-generic: Fix locking with drm_client_buffer_vmap_local()
>   drm/client: Pin vmap'ed GEM buffers
>   drm/gem-vram: Do not pin buffer objects for vmap
>   drm/qxl: Do not pin buffer objects for vmap
The patches look good. I gave them fbtest on virtio-gpu, no problems
spotted.

Reviewed-by: Dmitry Osipenko <dmitry.osipenko at collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko at collabora.com> # virtio-gpu

-- 
Best regards,
Dmitry

Nouveau - Feb 2024 - [PATCH 08/13] drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

[PATCH 01/13] drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks

[PATCH 02/13] drm/gem-vram: Acquire reservation lock in GEM pin/unpin callbacks

[PATCH 03/13] drm/msm: Provide msm_gem_get_pages_locked()

[PATCH 04/13] drm/msm: Acquire reservation lock in GEM pin/unpin callback

[PATCH 05/13] drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked()

[PATCH 06/13] drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks

[PATCH 07/13] drm/qxl: Provide qxl_bo_{pin,unpin}_locked()

[PATCH 08/13] drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks

[PATCH 09/13] drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}()

[PATCH 10/13] drm/fbdev-generic: Fix locking with drm_client_buffer_vmap_local()

[PATCH 11/13] drm/client: Pin vmap'ed GEM buffers

[PATCH 12/13] drm/gem-vram: Do not pin buffer objects for vmap

[PATCH 13/13] drm/qxl: Do not pin buffer objects for vmap

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console

[PATCH 00/13] drm: Fix reservation locking for pin/unpin and console