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.
Signed-off-by: Lianbo Jiang <liji...@redhat.com>
Co-developed-by: Robin Murphy <robin.mur...@arm.com>
Signed-off-by: Robin Murphy <robin.mur...@arm.com>
---
drivers/iommu/dma-iommu.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index f0305e6aac1b..3711b4a6e4f9 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -51,6 +51,8 @@ struct iommu_dma_cookie {
struct iommu_domain *fq_domain;
};
+static DEFINE_STATIC_KEY_FALSE(__deferred_attach);
+
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(&__deferred_attach) &&
+ 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(&__deferred_attach) &&
+ iommu_dma_deferred_attach(dev, domain))
return NULL;
min_size = alloc_sizes & -alloc_sizes;
@@ -1003,7 +1004,8 @@ 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(&__deferred_attach) &&
+ iommu_dma_deferred_attach(dev, domain))
return 0;
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
@@ -1451,6 +1453,9 @@ void iommu_dma_compose_msi_msg(struct msi_desc *desc,
static int iommu_dma_init(void)
{
+ if (is_kdump_kernel())
+ static_branch_enable(&__deferred_attach);
+
return iova_cache_get();
}
arch_initcall(iommu_dma_init);
--
2.17.1
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