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Commit 5507eef8 authored by Joerg Roedel's avatar Joerg Roedel Committed by Ingo Molnar
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AMD IOMMU: add branch hints to completion wait checks 



This patch adds branch hints to the cecks if a completion_wait is
necessary. The completion_waits in the mapping paths are unlikly because
they will only happen on software implementations of AMD IOMMU which
don't exists today or with lazy IO/TLB flushing when the allocator wraps
around the address space. With lazy IO/TLB flushing the completion_wait
in the unmapping path is unlikely too.

Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 1c655773

arch/x86/kernel/amd_iommu.c

+6 −6
Original line number Diff line number Diff line
@@ -876,7 +876,7 @@ static dma_addr_t map_single(struct device *dev, phys_addr_t paddr, 
	if (addr == bad_dma_address)

		goto out;



	if (iommu->need_sync)

	if (unlikely(iommu->need_sync))

		iommu_completion_wait(iommu);



out:
@@ -905,7 +905,7 @@ static void unmap_single(struct device *dev, dma_addr_t dma_addr, 


	__unmap_single(iommu, domain->priv, dma_addr, size, dir);



	if (iommu->need_sync)

	if (unlikely(iommu->need_sync))

		iommu_completion_wait(iommu);



	spin_unlock_irqrestore(&domain->lock, flags);
@@ -968,7 +968,7 @@ static int map_sg(struct device *dev, struct scatterlist *sglist, 
			goto unmap;

	}



	if (iommu->need_sync)

	if (unlikely(iommu->need_sync))

		iommu_completion_wait(iommu);



out:
@@ -1014,7 +1014,7 @@ static void unmap_sg(struct device *dev, struct scatterlist *sglist, 
		s->dma_address = s->dma_length = 0;

	}



	if (iommu->need_sync)

	if (unlikely(iommu->need_sync))

		iommu_completion_wait(iommu);



	spin_unlock_irqrestore(&domain->lock, flags);
@@ -1061,7 +1061,7 @@ static void *alloc_coherent(struct device *dev, size_t size, 
		goto out;

	}



	if (iommu->need_sync)

	if (unlikely(iommu->need_sync))

		iommu_completion_wait(iommu);



out:
@@ -1093,7 +1093,7 @@ static void free_coherent(struct device *dev, size_t size, 


	__unmap_single(iommu, domain->priv, dma_addr, size, DMA_BIDIRECTIONAL);



	if (iommu->need_sync)

	if (unlikely(iommu->need_sync))

		iommu_completion_wait(iommu);



	spin_unlock_irqrestore(&domain->lock, flags);