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powerpc/kernel/iommu: Use largepool as a last resort when !largealloc

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210318174414.684630-2-leobras.c@gmail.com
This commit is contained in:
Leonardo Bras 2021-03-18 14:44:17 -03:00 committed by Michael Ellerman
parent 3c0468d445
commit fc5590fd56
1 changed files with 9 additions and 0 deletions
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9
arch/powerpc/kernel/iommu.c
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@ -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);