dma-iommu: add iommu_dma_opt_mapping_size()

[ Upstream commit 6d9870b7e5def2450e21316515b9efc0529204dd ]

Add the IOMMU callback for DMA mapping API dma_opt_mapping_size(), which
allows the drivers to know the optimal mapping limit and thus limit the
requested IOVA lengths.

This value is based on the IOVA rcache range limit, as IOVAs allocated
above this limit must always be newly allocated, which may be quite slow.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Stable-dep-of: afc5aa46ed56 ("iommu/dma: Force swiotlb_max_mapping_size on an untrusted device")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 8cd63e6ccd2cfff871627b450ef64dd87b300106..a76a46e94a606c382fbcdf41b6b4275427ecf4bc 100644 (file)
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1291,6 +1291,11 @@ static unsigned long iommu_dma_get_merge_boundary(struct device *dev)
        return (1UL << __ffs(domain->pgsize_bitmap)) - 1;
 }
 
+static size_t iommu_dma_opt_mapping_size(void)
+{
+       return iova_rcache_range();
+}
+
 static const struct dma_map_ops iommu_dma_ops = {
        .alloc                  = iommu_dma_alloc,
        .free                   = iommu_dma_free,
@@ -1313,6 +1318,7 @@ static const struct dma_map_ops iommu_dma_ops = {
        .map_resource           = iommu_dma_map_resource,
        .unmap_resource         = iommu_dma_unmap_resource,
        .get_merge_boundary     = iommu_dma_get_merge_boundary,
+       .opt_mapping_size       = iommu_dma_opt_mapping_size,
 };
 
 /*

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 0835f32e040adbe053019f8f791529977fb273a5..f6dfb9e45e9535556ee4ef285e23245f6312e347 100644 (file)
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -27,6 +27,11 @@ static void free_iova_rcaches(struct iova_domain *iovad);
 static void fq_destroy_all_entries(struct iova_domain *iovad);
 static void fq_flush_timeout(struct timer_list *t);
 
+unsigned long iova_rcache_range(void)
+{
+       return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1);
+}
+
 static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
 {
        struct iova_domain *iovad;

diff --git a/include/linux/iova.h b/include/linux/iova.h
index 6b6cc104e300d155d5a551d5bad0916396226e49..9aa0acf9820af8a30a0ad26c5af6afabbf1e5484 100644 (file)
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -137,6 +137,8 @@ static inline unsigned long iova_pfn(struct iova_domain *iovad, dma_addr_t iova)
 int iova_cache_get(void);
 void iova_cache_put(void);
 
+unsigned long iova_rcache_range(void);
+
 void free_iova(struct iova_domain *iovad, unsigned long pfn);
 void __free_iova(struct iova_domain *iovad, struct iova *iova);
 struct iova *alloc_iova(struct iova_domain *iovad, unsigned long size,