From fc5590fd56c9608f317729b59a56dad2a75d633f Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Thu, 18 Mar 2021 14:44:17 -0300 Subject: [PATCH] powerpc/kernel/iommu: Use largepool as a last resort when !largealloc 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 Reviewed-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210318174414.684630-2-leobras.c@gmail.com --- arch/powerpc/kernel/iommu.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index 24208cd00aef..57d6b85e9b96 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -296,6 +296,15 @@ again: 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); -- 2.20.1