[PATCH v3 08/11] drm/xe: Add xe_tlb_inval_idle helper

Matthew Brost
2026-01-12T23:27:42Z

Introduce the xe_tlb_inval_idle helper to detect whether any TLB
invalidations are currently in flight. This is used in context-based TLB
invalidations to determine whether dummy TLB invalidations need to be
sent to maintain proper TLB invalidation fence ordering..

v2:
- Implement xe_tlb_inval_idle based on pending list

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
---
drivers/gpu/drm/xe/xe_tlb_inval.c | 21 +++++++++++++++++++++
drivers/gpu/drm/xe/xe_tlb_inval.h | 2 ++
2 files changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_tlb_inval.c b/drivers/gpu/drm/xe/xe_tlb_inval.c
index 014a78502fe5..daabc9370510 100644
--- a/drivers/gpu/drm/xe/xe_tlb_inval.c
+++ b/drivers/gpu/drm/xe/xe_tlb_inval.c
@@ -44,11 +44,14 @@ static void xe_tlb_inval_fence_fini(struct xe_tlb_inval_fence *fence)
static void
xe_tlb_inval_fence_signal(struct xe_tlb_inval_fence *fence)
{
+ struct xe_tlb_inval *tlb_inval = fence->tlb_inval;
bool stack = test_bit(FENCE_STACK_BIT, &fence->base.flags);

lockdep_assert_held(&fence->tlb_inval->pending_lock);

list_del(&fence->link);
+ if (list_empty(&tlb_inval->pending_fences))
+ cancel_delayed_work(&tlb_inval->fence_tdr);
trace_xe_tlb_inval_fence_signal(fence->tlb_inval->xe, fence);
xe_tlb_inval_fence_fini(fence);
dma_fence_signal(&fence->base);
@@ -464,3 +467,21 @@ void xe_tlb_inval_fence_init(struct xe_tlb_inval *tlb_inval,
dma_fence_get(&fence->base);
fence->tlb_inval = tlb_inval;
}
+
+/**
+ * xe_tlb_inval_idle() - Initialize TLB invalidation is idle
+ * @tlb_inval: TLB invalidation client
+ *
+ * Check the TLB invalidation seqno to determine if it is idle (i.e., no TLB
+ * invalidations are in flight). Expected to be called in the backend after the
+ * fence has been added to the pending list, and takes this into account.
+ *
+ * Return: True if TLB invalidation client is idle, False otherwise
+ */
+bool xe_tlb_inval_idle(struct xe_tlb_inval *tlb_inval)
+{
+ lockdep_assert_held(&tlb_inval->seqno_lock);
+
+ guard(spinlock_irq)(&tlb_inval->pending_lock);
+ return list_is_singular(&tlb_inval->pending_fences);
+}
diff --git a/drivers/gpu/drm/xe/xe_tlb_inval.h b/drivers/gpu/drm/xe/xe_tlb_inval.h
index 858d0690f995..62089254fa23 100644
--- a/drivers/gpu/drm/xe/xe_tlb_inval.h
+++ b/drivers/gpu/drm/xe/xe_tlb_inval.h
@@ -43,4 +43,6 @@ xe_tlb_inval_fence_wait(struct xe_tlb_inval_fence *fence)

void xe_tlb_inval_done_handler(struct xe_tlb_inval *tlb_inval, int seqno);

+bool xe_tlb_inval_idle(struct xe_tlb_inval *tlb_inval);
+
#endif /* _XE_TLB_INVAL_ */
--
2.34.1