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

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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: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20210126115337.20068-2-lijiang@redhat.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Lianbo Jiang 2021-01-26 19:53:36 +08:00 committed by Joerg Roedel
parent 262948f8ba
commit a8e8af35c9
1 changed files with 11 additions and 6 deletions
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17
drivers/iommu/dma-iommu.c
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@ -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);