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Message-ID: <20250819114932.597600-8-dev@lankhorst.se>
Date: Tue, 19 Aug 2025 13:49:36 +0200
From: Maarten Lankhorst <dev@...khorst.se>
To: Lucas De Marchi <lucas.demarchi@...el.com>,
'Thomas Hellström' <thomas.hellstrom@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>,
Maarten Lankhorst <dev@...khorst.se>,
Maxime Ripard <mripard@...nel.org>,
Natalie Vock <natalie.vock@....de>,
Tejun Heo <tj@...nel.org>,
Johannes Weiner <hannes@...xchg.org>,
'Michal Koutný' <mkoutny@...e.com>,
Michal Hocko <mhocko@...nel.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Shakeel Butt <shakeel.butt@...ux.dev>,
Muchun Song <muchun.song@...ux.dev>,
Andrew Morton <akpm@...ux-foundation.org>,
David Hildenbrand <david@...hat.com>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
"'Liam R . Howlett'" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Mike Rapoport <rppt@...nel.org>,
Suren Baghdasaryan <surenb@...gle.com>,
Thomas Zimmermann <tzimmermann@...e.de>
Cc: Michal Hocko <mhocko@...e.com>,
intel-xe@...ts.freedesktop.org,
dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org,
cgroups@...r.kernel.org,
linux-mm@...ck.org
Subject: [RFC 3/3] drm/xe: Add DRM_XE_GEM_CREATE_FLAG_PINNED flag and implementation
Add an option to pin memory through the science of cgroup accounting.
A bo will be pinned for its entire lifetime, and this allows buffers
that are pinned for dma-buf export without requiring the pinning to be
done at the dma-buf layer for all devices.
For now only implement VRAM pinning. Dave Airlie has a series to implement
memcg accounting for the GPU but that is not ready yet.
Signed-off-by: Maarten Lankhorst <dev@...khorst.se>
---
drivers/gpu/drm/xe/xe_bo.c | 66 ++++++++++++++++++++++++++++++++-
drivers/gpu/drm/xe/xe_dma_buf.c | 10 ++++-
include/uapi/drm/xe_drm.h | 10 ++++-
3 files changed, 82 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 6fea39842e1e6..4095e6bd04ea9 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -5,6 +5,7 @@
#include "xe_bo.h"
+#include <linux/cgroup_dmem.h>
#include <linux/dma-buf.h>
#include <linux/nospec.h>
@@ -208,7 +209,8 @@ static bool force_contiguous(u32 bo_flags)
* must be contiguous, also only contiguous BOs support xe_bo_vmap.
*/
return bo_flags & XE_BO_FLAG_NEEDS_CPU_ACCESS &&
- bo_flags & XE_BO_FLAG_PINNED;
+ bo_flags & XE_BO_FLAG_PINNED &&
+ !(bo_flags & XE_BO_FLAG_USER);
}
static void add_vram(struct xe_device *xe, struct xe_bo *bo,
@@ -1697,6 +1699,16 @@ static void xe_gem_object_free(struct drm_gem_object *obj)
ttm_bo_put(container_of(obj, struct ttm_buffer_object, base));
}
+static void xe_bo_unpin_user(struct xe_bo *bo)
+{
+ xe_bo_unpin_external(bo);
+
+ if (bo->flags & XE_BO_FLAG_SYSTEM)
+ WARN_ON(1);
+ else
+ dmem_cgroup_unpin(bo->ttm.resource->css, xe_bo_size(bo));
+}
+
static void xe_gem_object_close(struct drm_gem_object *obj,
struct drm_file *file_priv)
{
@@ -1708,6 +1720,10 @@ static void xe_gem_object_close(struct drm_gem_object *obj,
xe_bo_lock(bo, false);
ttm_bo_set_bulk_move(&bo->ttm, NULL);
xe_bo_unlock(bo);
+ } else if (bo->flags & XE_BO_FLAG_PINNED) {
+ xe_bo_lock(bo, false);
+ xe_bo_unpin_user(bo);
+ xe_bo_unlock(bo);
}
}
@@ -2128,8 +2144,27 @@ struct xe_bo *xe_bo_create_user(struct xe_device *xe, struct xe_tile *tile,
struct xe_bo *bo = __xe_bo_create_locked(xe, tile, vm, size, 0, ~0ULL,
cpu_caching, ttm_bo_type_device,
flags | XE_BO_FLAG_USER, 0);
- if (!IS_ERR(bo))
+ if (!IS_ERR(bo)) {
+ int ret = 0;
+
+ if (bo->flags & XE_BO_FLAG_PINNED) {
+ if (bo->flags & XE_BO_FLAG_SYSTEM) {
+ ret = -ENOSYS; // TODO
+ } else {
+ ret = dmem_cgroup_try_pin(bo->ttm.resource->css, size);
+ }
+ if (!ret)
+ ret = xe_bo_pin_external(bo);
+ else if (ret == -EAGAIN)
+ ret = -ENOSPC;
+ }
+
xe_bo_unlock_vm_held(bo);
+ if (ret) {
+ xe_bo_put(bo);
+ return ERR_PTR(ret);
+ }
+ }
return bo;
}
@@ -2745,6 +2780,28 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
args->cpu_caching == DRM_XE_GEM_CPU_CACHING_WB))
return -EINVAL;
+ if (XE_IOCTL_DBG(xe, args->flags & DRM_XE_GEM_CREATE_FLAG_PINNED)) {
+ bool pinned_flag = true;
+ /* Only allow a single placement for pinning */
+ if (XE_IOCTL_DBG(xe, pinned_flag && hweight32(args->placement) != 1))
+ return -EINVAL;
+
+ /* Meant for exporting, do not allow a VM-local BO */
+ if (XE_IOCTL_DBG(xe, pinned_flag && args->vm_id))
+ return -EINVAL;
+
+ /* Similarly, force fail at creation time for now. We may relax this requirement later */
+ if (XE_IOCTL_DBG(xe, pinned_flag && args->flags & DRM_XE_GEM_CREATE_FLAG_DEFER_BACKING))
+ return -EINVAL;
+
+ /* Require the appropriate cgroups to be enabled. */
+ if (XE_IOCTL_DBG(xe, pinned_flag && !IS_ENABLED(CONFIG_CGROUP_DMEM) && bo_flags & XE_BO_FLAG_VRAM_MASK) ||
+ XE_IOCTL_DBG(xe, pinned_flag && !IS_ENABLED(CONFIG_MEMCG) && bo_flags & XE_BO_FLAG_SYSTEM))
+ return -EINVAL;
+
+ bo_flags |= XE_BO_FLAG_PINNED;
+ }
+
if (args->vm_id) {
vm = xe_vm_lookup(xef, args->vm_id);
if (XE_IOCTL_DBG(xe, !vm))
@@ -2790,6 +2847,11 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
__xe_bo_unset_bulk_move(bo);
xe_vm_unlock(vm);
}
+ if (bo->flags & XE_BO_FLAG_PINNED) {
+ xe_bo_lock(bo, false);
+ xe_bo_unpin_user(bo);
+ xe_bo_unlock(bo);
+ }
out_put:
xe_bo_put(bo);
out_vm:
diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c
index 346f857f38374..6719f4552ad37 100644
--- a/drivers/gpu/drm/xe/xe_dma_buf.c
+++ b/drivers/gpu/drm/xe/xe_dma_buf.c
@@ -53,6 +53,11 @@ static int xe_dma_buf_pin(struct dma_buf_attachment *attach)
struct xe_device *xe = xe_bo_device(bo);
int ret;
+ if (bo->flags & XE_BO_FLAG_PINNED) {
+ ttm_bo_pin(&bo->ttm);
+ return 0;
+ }
+
/*
* For now only support pinning in TT memory, for two reasons:
* 1) Avoid pinning in a placement not accessible to some importers.
@@ -83,7 +88,10 @@ static void xe_dma_buf_unpin(struct dma_buf_attachment *attach)
struct drm_gem_object *obj = attach->dmabuf->priv;
struct xe_bo *bo = gem_to_xe_bo(obj);
- xe_bo_unpin_external(bo);
+ if (bo->flags & XE_BO_FLAG_PINNED)
+ ttm_bo_unpin(&bo->ttm);
+ else
+ xe_bo_unpin_external(bo);
}
static struct sg_table *xe_dma_buf_map(struct dma_buf_attachment *attach,
diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
index c721e130c1d2d..3184fa38ce17e 100644
--- a/include/uapi/drm/xe_drm.h
+++ b/include/uapi/drm/xe_drm.h
@@ -765,12 +765,15 @@ struct drm_xe_device_query {
* until the object is either bound to a virtual memory region via
* VM_BIND or accessed by the CPU. As a result, no backing memory is
* reserved at the time of GEM object creation.
- * - %DRM_XE_GEM_CREATE_FLAG_SCANOUT
+ * - %DRM_XE_GEM_CREATE_FLAG_SCANOUT - GEM object will be used
+ * display framebuffer.
* - %DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM - When using VRAM as a
* possible placement, ensure that the corresponding VRAM allocation
* will always use the CPU accessible part of VRAM. This is important
* for small-bar systems (on full-bar systems this gets turned into a
* noop).
+ * - %DRM_XE_GEM_CREATE_FLAG_PINNED - Pin the backing memory permanently
+ * on allocation, if withing cgroups limits.
* Note1: System memory can be used as an extra placement if the kernel
* should spill the allocation to system memory, if space can't be made
* available in the CPU accessible part of VRAM (giving the same
@@ -781,6 +784,10 @@ struct drm_xe_device_query {
* need to use VRAM for display surfaces, therefore the kernel requires
* setting this flag for such objects, otherwise an error is thrown on
* small-bar systems.
+ * Note3: %DRM_XE_GEM_CREATE_FLAG_PINNED requires the BO to have only
+ * a single placement, no vm_id, requires (device) memory cgroups enabled,
+ * and is incompatible with the %DEFER_BACKING and %NEEDS_VISIBLE_VRAM
+ * flags.
*
* @cpu_caching supports the following values:
* - %DRM_XE_GEM_CPU_CACHING_WB - Allocate the pages with write-back
@@ -827,6 +834,7 @@ struct drm_xe_gem_create {
#define DRM_XE_GEM_CREATE_FLAG_DEFER_BACKING (1 << 0)
#define DRM_XE_GEM_CREATE_FLAG_SCANOUT (1 << 1)
#define DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM (1 << 2)
+#define DRM_XE_GEM_CREATE_FLAG_PINNED (1 << 3)
/**
* @flags: Flags, currently a mask of memory instances of where BO can
* be placed
--
2.50.0
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