diff mbox series

[v2,04/14] powerpc/kernel/iommu: Use largepool as a last resort when !largealloc

Message ID 20200911170738.82818-5-leobras.c@gmail.com (mailing list archive)
State Superseded, archived
Headers show
Series DDW Indirect Mapping | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (4b552a4cbf286ff9dcdab19153f3c1c7d1680fab)
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 15 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Leonardo Brás Sept. 11, 2020, 5:07 p.m. UTC 
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, 

As of today, doing iommu_range_alloc() only for !largealloc (npages <= 15)
will only be able to use 3/4 of the available pages, given pages on
largepool  not being available for !largealloc.

This could mean some drivers not being able to fully use all the available
pages for the DMA window.

Add pages on largepool as a last resort for !largealloc, making all pages
of the DMA window available.

Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/kernel/iommu.c | 9 +++++++++
 1 file changed, 9 insertions(+)
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 7961645a6980..ffb2637dc82b 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -261,6 +261,15 @@  static unsigned long iommu_range_alloc(struct device *dev,
 			pass++;
 			goto again;
 
+		} else if (pass == tbl->nr_pools + 1) {
+			/* Last resort: try largepool */
+			spin_unlock(&pool->lock);
+			pool = &tbl->large_pool;
+			spin_lock(&pool->lock);
+			pool->hint = pool->start;
+			pass++;
+			goto again;
+
 		} else {
 			/* Give up */
 			spin_unlock_irqrestore(&(pool->lock), flags);