[Intel-xe] [RFC PATCH] drm/xe/dgfx: Release mmap mappings on rpm suspend
Rodrigo Vivi
rodrigo.vivi at intel.com
Wed Aug 30 21:04:41 UTC 2023
On Mon, Aug 28, 2023 at 10:00:31PM +0530, Nilawar, Badal wrote:
>
>
> On 28-08-2023 17:46, Gupta, Anshuman wrote:
> >
> >
> > > -----Original Message-----
> > > From: Nilawar, Badal <badal.nilawar at intel.com>
> > > Sent: Thursday, August 24, 2023 11:16 PM
> > > To: intel-xe at lists.freedesktop.org
> > > Cc: Gupta, Anshuman <anshuman.gupta at intel.com>; Auld, Matthew
> > > <matthew.auld at intel.com>; Vivi, Rodrigo <rodrigo.vivi at intel.com>
> > > Subject: [RFC PATCH] drm/xe/dgfx: Release mmap mappings on rpm
> > > suspend
> > >
> > > Release all mmap mappings for all vram objects which are associated with
> > > userfault such that, while pcie function in D3hot, any access to memory
> > > mappings will raise a userfault.
> > >
> > > Upon userfault, in order to access memory mappings, if graphics function is in
> > > D3 then runtime resume of dgpu will be triggered to transition to D0.
> > IMO we need a configurable threshold to control the behavior of mmap mappings
> > Invalidation, if vram usages is crosses to certain threshold, disable the runtime PM for
> > entire life time of mapping.
> Agreed. Other option could be disable rpm on server descrete graphics for
> entire life time of mapping. But mainitaning threshold is more promising and
> gives control to user.
what use cases we have here for this?
I believe that for discrete we could entirely block rpm if we have display
or if we have shared dma_buf. any other case we should handle?
>
> Regards,
> Badal
> > Thanks,
> > Anshuman Gupta
> > >
> > > Cc: Matthew Auld <matthew.auld at intel.com>
> > > Cc: Anshuman Gupta <anshuman.gupta at intel.com>
> > > Signed-off-by: Badal Nilawar <badal.nilawar at intel.com>
> > > ---
> > > drivers/gpu/drm/xe/xe_bo.c | 53 ++++++++++++++++++++++++++--
> > > drivers/gpu/drm/xe/xe_bo.h | 2 ++
> > > drivers/gpu/drm/xe/xe_bo_types.h | 6 ++++
> > > drivers/gpu/drm/xe/xe_device_types.h | 20 +++++++++++
> > > drivers/gpu/drm/xe/xe_pm.c | 7 ++++
> > > 5 files changed, 85 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> > > index 1ab682d61e3c..4192bfcd8013 100644
> > > --- a/drivers/gpu/drm/xe/xe_bo.c
> > > +++ b/drivers/gpu/drm/xe/xe_bo.c
> > > @@ -776,6 +776,18 @@ static int xe_bo_move(struct ttm_buffer_object
> > > *ttm_bo, bool evict,
> > > dma_fence_put(fence);
> > > }
> > >
> > > + /*
> > > + * TTM has already nuked the mmap for us (see
> > > ttm_bo_unmap_virtual),
> > > + * so if we moved from VRAM make sure to unlink this from the
> > > userfault
> > > + * tracking.
> > > + */
> > > + if (mem_type_is_vram(old_mem_type)) {
> > > + spin_lock(&xe->mem_access.vram_userfault_lock);
> > > + if (!list_empty(&bo->vram_userfault_link))
> > > + list_del_init(&bo->vram_userfault_link);
> > > + spin_unlock(&xe->mem_access.vram_userfault_lock);
> > > + }
> > > +
> > > xe_device_mem_access_put(xe);
> > > trace_printk("new_mem->mem_type=%d\n", new_mem-
> > > > mem_type);
> > >
> > > @@ -1100,6 +1112,8 @@ static vm_fault_t xe_gem_fault(struct vm_fault
> > > *vmf) {
> > > struct ttm_buffer_object *tbo = vmf->vma->vm_private_data;
> > > struct drm_device *ddev = tbo->base.dev;
> > > + struct xe_bo *bo = ttm_to_xe_bo(tbo);
> > > + struct xe_device *xe = to_xe_device(ddev);
> > > vm_fault_t ret;
> > > int idx, r = 0;
> > >
> > > @@ -1107,9 +1121,10 @@ static vm_fault_t xe_gem_fault(struct vm_fault
> > > *vmf)
> > > if (ret)
> > > return ret;
> > >
> > > - if (drm_dev_enter(ddev, &idx)) {
> > > - struct xe_bo *bo = ttm_to_xe_bo(tbo);
> > > + if (tbo->resource->bus.is_iomem)
> > > + xe_device_mem_access_get(xe);
> > >
> > > + if (drm_dev_enter(ddev, &idx)) {
> > > trace_xe_bo_cpu_fault(bo);
> > >
> > > if (should_migrate_to_system(bo)) {
> > > @@ -1127,10 +1142,25 @@ static vm_fault_t xe_gem_fault(struct vm_fault
> > > *vmf)
> > > } else {
> > > ret = ttm_bo_vm_dummy_page(vmf, vmf->vma-
> > > > vm_page_prot);
> > > }
> > > +
> > > if (ret == VM_FAULT_RETRY && !(vmf->flags &
> > > FAULT_FLAG_RETRY_NOWAIT))
> > > - return ret;
> > > + goto out_rpm;
> > > + /*
> > > + * ttm_bo_vm_reserve() already has dma_resv_lock.
> > > + * vram_userfault_count is protected by dma_resv lock and rpm
> > > wakeref.
> > > + */
> > > + if (ret == VM_FAULT_NOPAGE &&
> > > xe_device_mem_access_ongoing(xe) && !bo->vram_userfault_count) {
> > > + bo->vram_userfault_count = 1;
> > > + spin_lock(&xe->mem_access.vram_userfault_lock);
> > > + list_add(&bo->vram_userfault_link, &xe-
> > > > mem_access.vram_userfault_list);
> > > + spin_unlock(&xe->mem_access.vram_userfault_lock);
> > >
> > > + XE_WARN_ON(!tbo->resource->bus.is_iomem);
> > > + }
> > > dma_resv_unlock(tbo->base.resv);
> > > +out_rpm:
> > > + if(tbo->resource->bus.is_iomem &&
> > > xe_device_mem_access_ongoing(xe))
> > > + xe_device_mem_access_put(xe);
> > > return ret;
> > > }
> > >
> > > @@ -2108,6 +2138,23 @@ int xe_bo_dumb_create(struct drm_file
> > > *file_priv,
> > > return err;
> > > }
> > >
> > > +void xe_bo_runtime_pm_release_mmap_offset(struct xe_bo *bo) {
> > > + struct ttm_buffer_object *tbo = &bo->ttm;
> > > + struct ttm_device *bdev = tbo->bdev;
> > > +
> > > + drm_vma_node_unmap(&tbo->base.vma_node, bdev-
> > > > dev_mapping);
> > > +
> > > + /*
> > > + * We have exclusive access here via runtime suspend. All other
> > > callers
> > > + * must first grab the rpm wakeref.
> > > + */
> > > + XE_WARN_ON(!bo->vram_userfault_count);
> > > + list_del(&bo->vram_userfault_link);
> > > + bo->vram_userfault_count = 0;
> > > +}
> > > +
> > > +
> > > #if IS_ENABLED(CONFIG_DRM_XE_KUNIT_TEST)
> > > #include "tests/xe_bo.c"
> > > #endif
> > > diff --git a/drivers/gpu/drm/xe/xe_bo.h b/drivers/gpu/drm/xe/xe_bo.h
> > > index 0823dda0f31b..6b86f326c700 100644
> > > --- a/drivers/gpu/drm/xe/xe_bo.h
> > > +++ b/drivers/gpu/drm/xe/xe_bo.h
> > > @@ -247,6 +247,8 @@ int xe_gem_create_ioctl(struct drm_device *dev,
> > > void *data,
> > > struct drm_file *file);
> > > int xe_gem_mmap_offset_ioctl(struct drm_device *dev, void *data,
> > > struct drm_file *file);
> > > +void xe_bo_runtime_pm_release_mmap_offset(struct xe_bo *bo);
> > > +
> > > int xe_bo_dumb_create(struct drm_file *file_priv,
> > > struct drm_device *dev,
> > > struct drm_mode_create_dumb *args); diff --git
> > > a/drivers/gpu/drm/xe/xe_bo_types.h
> > > b/drivers/gpu/drm/xe/xe_bo_types.h
> > > index f6ee920303af..cdca91a378c4 100644
> > > --- a/drivers/gpu/drm/xe/xe_bo_types.h
> > > +++ b/drivers/gpu/drm/xe/xe_bo_types.h
> > > @@ -68,6 +68,12 @@ struct xe_bo {
> > > struct llist_node freed;
> > > /** @created: Whether the bo has passed initial creation */
> > > bool created;
> > > + /**
> > > + * Whether the object is currently in fake offset mmap backed by
> > > vram.
> > > + */
> > > + unsigned int vram_userfault_count;
> > > + struct list_head vram_userfault_link;
> > > +
> > > };
> > >
> > > #endif
> > > diff --git a/drivers/gpu/drm/xe/xe_device_types.h
> > > b/drivers/gpu/drm/xe/xe_device_types.h
> > > index 750e1f0d3339..c345fb483af1 100644
> > > --- a/drivers/gpu/drm/xe/xe_device_types.h
> > > +++ b/drivers/gpu/drm/xe/xe_device_types.h
> > > @@ -328,6 +328,26 @@ struct xe_device {
> > > struct {
> > > /** @ref: ref count of memory accesses */
> > > atomic_t ref;
> > > + /*
> > > + * Protects access to vram usefault list.
> > > + * It is required, if we are outside of the runtime suspend
> > > path,
> > > + * access to @vram_userfault_list requires always first
> > > grabbing the
> > > + * runtime pm, to ensure we can't race against runtime
> > > suspend.
> > > + * Once we have that we also need to grab
> > > @vram_userfault_lock,
> > > + * at which point we have exclusive access.
> > > + * The runtime suspend path is special since it doesn't really
> > > hold any locks,
> > > + * but instead has exclusive access by virtue of all other
> > > accesses requiring
> > > + * holding the runtime pm wakeref.
> > > + */
> > > + spinlock_t vram_userfault_lock;
> > > +
> > > + /*
> > > + * Keep list of userfaulted gem obj, which require to release
> > > their
> > > + * mmap mappings at runtime suspend path.
> > > + */
> > > + struct list_head vram_userfault_list;
> > > +
> > > + bool vram_userfault_ongoing;
> > > } mem_access;
> > >
> > > /** @d3cold: Encapsulate d3cold related stuff */ diff --git
> > > a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c index
> > > 0f06d8304e17..51cde1db930e 100644
> > > --- a/drivers/gpu/drm/xe/xe_pm.c
> > > +++ b/drivers/gpu/drm/xe/xe_pm.c
> > > @@ -172,6 +172,8 @@ void xe_pm_init(struct xe_device *xe)
> > > }
> > >
> > > xe_pm_runtime_init(xe);
> > > + INIT_LIST_HEAD(&xe->mem_access.vram_userfault_list);
> > > + spin_lock_init(&xe->mem_access.vram_userfault_lock);
> > > }
> > >
> > > void xe_pm_runtime_fini(struct xe_device *xe) @@ -205,6 +207,7 @@
> > > struct task_struct *xe_pm_read_callback_task(struct xe_device *xe)
> > >
> > > int xe_pm_runtime_suspend(struct xe_device *xe) {
> > > + struct xe_bo *bo, *on;
> > > struct xe_gt *gt;
> > > u8 id;
> > > int err = 0;
> > > @@ -238,6 +241,10 @@ int xe_pm_runtime_suspend(struct xe_device *xe)
> > > */
> > > lock_map_acquire(&xe_device_mem_access_lockdep_map);
> > >
> > > + list_for_each_entry_safe(bo, on,
> > > + &xe->mem_access.vram_userfault_list,
> > > vram_userfault_link)
> > > + xe_bo_runtime_pm_release_mmap_offset(bo);
> > > +
> > > if (xe->d3cold.allowed) {
> > > err = xe_bo_evict_all(xe);
> > > if (err)
> > > --
> > > 2.25.1
> >
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