From: Matthew Brost <[email protected]> Drivers which only use the drm_gpusvm_pages API (no drm_gpusvm_range) have no way to mark pages unmapped from their MMU notifier, as drm_gpusvm_range_set_unmapped() requires a range. They also have to open code the mmu_interval_read_retry() check on the recorded notifier_seq to commit pages faulted with &drm_gpusvm_ctx.no_dma_map.
Split the pages part of drm_gpusvm_range_set_unmapped() into drm_gpusvm_pages_set_unmapped(), and add drm_gpusvm_pages_read_retry() which performs the commit side check with a lockdep assert on the notifier lock. Assisted-by: LLM Signed-off-by: Matthew Brost <[email protected]> Signed-off-by: Lizhi Hou <[email protected]> --- drivers/gpu/drm/drm_gpusvm.c | 49 +++++++++++++++++++++++++----------- include/drm/drm_gpusvm.h | 29 +++++++++++++++++++++ 2 files changed, 64 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c index 03dbe304e4b8f..63a26919f59db 100644 --- a/drivers/gpu/drm/drm_gpusvm.c +++ b/drivers/gpu/drm/drm_gpusvm.c @@ -1761,9 +1761,8 @@ static int drm_gpusvm_dma_map_pages(struct drm_gpusvm *gpusvm, * * With &drm_gpusvm_ctx.no_dma_map no mapping state is recorded, so * drm_gpusvm_pages_valid() never returns true and success is only a snapshot: - * the caller must recheck mmu_interval_read_retry() against the recorded - * &drm_gpusvm_pages.notifier_seq under the notifier lock, and hold it until - * its work is visible to invalidation. + * the caller must recheck drm_gpusvm_pages_read_retry() under the notifier + * lock, and hold it until its work is visible to invalidation. * * Return: 0 on success, negative error code on failure. */ @@ -2021,6 +2020,38 @@ bool drm_gpusvm_has_mapping(struct drm_gpusvm *gpusvm, unsigned long start, } EXPORT_SYMBOL_GPL(drm_gpusvm_has_mapping); +/** + * drm_gpusvm_pages_set_unmapped() - Mark GPU SVM pages as unmapped + * @gpusvm: Pointer to the GPU SVM structure. + * @pages: Pointer to the GPU SVM pages structure(s). + * @pages_count: Number of GPU SVM pages structure(s) passed in. + * + * Mark @pages as unmapped, after which drm_gpusvm_get_pages() fails with + * -EFAULT for them. Intended to be called from the driver's MMU notifier on + * MMU_NOTIFY_UNMAP, and usable without a &drm_gpusvm_range by drivers that + * only use the drm_gpusvm_pages API. The caller must hold the notifier lock + * in write mode. + */ +void drm_gpusvm_pages_set_unmapped(struct drm_gpusvm *gpusvm, + struct drm_gpusvm_pages *pages, + unsigned int pages_count) +{ + unsigned int i; + + lockdep_assert_held_write(&gpusvm->notifier_lock); + + for (i = 0; i < pages_count; ++i) { + struct drm_gpusvm_pages_flags flags = { + .__flags = pages[i].flags.__flags, + }; + + flags.unmapped = true; + /* WRITE_ONCE pairs with READ_ONCE for opportunistic checks */ + WRITE_ONCE(pages[i].flags.__flags, flags.__flags); + } +} +EXPORT_SYMBOL_GPL(drm_gpusvm_pages_set_unmapped); + /** * drm_gpusvm_range_set_unmapped() - Mark a GPU SVM range as unmapped * @range: Pointer to the GPU SVM range structure. @@ -2039,20 +2070,10 @@ void drm_gpusvm_range_set_unmapped(struct drm_gpusvm_range *range, struct drm_gpusvm_range_flags range_flags = { .__flags = range->flags.__flags, }; - unsigned int i; - lockdep_assert_held_write(&range->gpusvm->notifier_lock); + drm_gpusvm_pages_set_unmapped(range->gpusvm, pages, pages_count); range_flags.unmapped = true; - for (i = 0; i < pages_count; ++i) { - struct drm_gpusvm_pages_flags flags = { - .__flags = pages[i].flags.__flags, - }; - - flags.unmapped = true; - /* WRITE_ONCE pairs with READ_ONCE for opportunistic checks */ - WRITE_ONCE(pages[i].flags.__flags, flags.__flags); - } if (drm_gpusvm_range_start(range) < mmu_range->start || drm_gpusvm_range_end(range) > mmu_range->end) range_flags.partial_unmap = true; diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h index 4d31c6bba7455..b43432af56377 100644 --- a/include/drm/drm_gpusvm.h +++ b/include/drm/drm_gpusvm.h @@ -349,6 +349,10 @@ void drm_gpusvm_range_set_unmapped(struct drm_gpusvm_range *range, unsigned int pages_count, const struct mmu_notifier_range *mmu_range); +void drm_gpusvm_pages_set_unmapped(struct drm_gpusvm *gpusvm, + struct drm_gpusvm_pages *pages, + unsigned int pages_count); + int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, struct drm_gpusvm_pages *svm_pages, unsigned int num_pages, @@ -383,6 +387,31 @@ static inline void drm_gpusvm_init_pages(struct drm_gpusvm_pages *svm_pages, svm_pages->notifier_seq = LONG_MAX; } +/** + * drm_gpusvm_pages_read_retry() - Check whether GPU SVM pages went stale + * @gpusvm: Pointer to the GPU SVM structure. + * @svm_pages: Pointer to the drm_gpusvm_pages. + * @notifier: The notifier passed to drm_gpusvm_get_pages() for @svm_pages. + * + * Check whether @notifier was invalidated since the last successful + * drm_gpusvm_get_pages() for @svm_pages. This is the commit side check for + * pages faulted with &drm_gpusvm_ctx.no_dma_map, where no mapping state is + * tracked. Pages that were never faulted always report as stale. The caller + * must hold the notifier lock and keep holding it until its use of the pages + * is visible to the invalidation path. + * + * Return: True if the pages must be faulted again, false otherwise. + */ +static inline bool +drm_gpusvm_pages_read_retry(struct drm_gpusvm *gpusvm, + struct drm_gpusvm_pages *svm_pages, + struct mmu_interval_notifier *notifier) +{ + lockdep_assert_held(&gpusvm->notifier_lock); + + return mmu_interval_read_retry(notifier, svm_pages->notifier_seq); +} + /** * drm_gpusvm_pages_first_dma() - Resolve the device address array * @svm_pages: Pointer to the drm_gpusvm_pages. base-commit: d2a8cee91bfa8616f713c7c8f539a81e8e3554ea -- 2.34.1
