Commit a8e8af35 authored by Lianbo Jiang's avatar Lianbo Jiang Committed by Joerg Roedel
Browse files

dma-iommu: use static-key to minimize the impact in the fast-path 



Let's move out the is_kdump_kernel() check from iommu_dma_deferred_attach()
to iommu_dma_init(), and use the static-key in the fast-path to minimize
the impact in the normal case.

Co-developed-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarLianbo Jiang <lijiang@redhat.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20210126115337.20068-2-lijiang@redhat.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 262948f8

drivers/iommu/dma-iommu.c

+11 −6
Original line number Diff line number Diff line
@@ -51,6 +51,8 @@ struct iommu_dma_cookie { 
	struct iommu_domain		*fq_domain;

};



static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);



void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,

		struct iommu_domain *domain)

{
@@ -383,9 +385,6 @@ static int iommu_dma_deferred_attach(struct device *dev, 
{

	const struct iommu_ops *ops = domain->ops;



	if (!is_kdump_kernel())

		return 0;



	if (unlikely(ops->is_attach_deferred &&

			ops->is_attach_deferred(domain, dev)))

		return iommu_attach_device(domain, dev);
@@ -535,7 +534,8 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys, 
	size_t iova_off = iova_offset(iovad, phys);

	dma_addr_t iova;



	if (unlikely(iommu_dma_deferred_attach(dev, domain)))

	if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&

	    iommu_dma_deferred_attach(dev, domain))

		return DMA_MAPPING_ERROR;



	size = iova_align(iovad, size + iova_off);
@@ -693,7 +693,8 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size, 


	*dma_handle = DMA_MAPPING_ERROR;



	if (unlikely(iommu_dma_deferred_attach(dev, domain)))

	if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&

	    iommu_dma_deferred_attach(dev, domain))

		return NULL;



	min_size = alloc_sizes & -alloc_sizes;
@@ -976,7 +977,8 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, 
	unsigned long mask = dma_get_seg_boundary(dev);

	int i;



	if (unlikely(iommu_dma_deferred_attach(dev, domain)))

	if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&

	    iommu_dma_deferred_attach(dev, domain))

		return 0;



	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
@@ -1424,6 +1426,9 @@ void iommu_dma_compose_msi_msg(struct msi_desc *desc, 


static int iommu_dma_init(void)

{

	if (is_kdump_kernel())

		static_branch_enable(&iommu_deferred_attach_enabled);



	return iova_cache_get();

}

arch_initcall(iommu_dma_init);