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iommu/iova: Improve 32-bit free space estimate
commit 5b61343b50
upstream.
For various reasons based on the allocator behaviour and typical
use-cases at the time, when the max32_alloc_size optimisation was
introduced it seemed reasonable to couple the reset of the tracked
size to the update of cached32_node upon freeing a relevant IOVA.
However, since subsequent optimisations focused on helping genuine
32-bit devices make best use of even more limited address spaces, it
is now a lot more likely for cached32_node to be anywhere in a "full"
32-bit address space, and as such more likely for space to become
available from IOVAs below that node being freed.
At this point, the short-cut in __cached_rbnode_delete_update() really
doesn't hold up any more, and we need to fix the logic to reliably
provide the expected behaviour. We still want cached32_node to only move
upwards, but we should reset the allocation size if *any* 32-bit space
has become available.
Reported-by: Yunfei Wang <yf.wang@mediatek.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Link: https://lore.kernel.org/r/033815732d83ca73b13c11485ac39336f15c3b40.1646318408.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Cc: Miles Chen <miles.chen@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
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commit
8a4521456b
1 changed files with 3 additions and 2 deletions
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@ -154,10 +154,11 @@ __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
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cached_iova = to_iova(iovad->cached32_node);
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if (free == cached_iova ||
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(free->pfn_hi < iovad->dma_32bit_pfn &&
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free->pfn_lo >= cached_iova->pfn_lo)) {
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free->pfn_lo >= cached_iova->pfn_lo))
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iovad->cached32_node = rb_next(&free->node);
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if (free->pfn_lo < iovad->dma_32bit_pfn)
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iovad->max32_alloc_size = iovad->dma_32bit_pfn;
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}
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cached_iova = to_iova(iovad->cached_node);
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if (free->pfn_lo >= cached_iova->pfn_lo)
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