[PATCH 4/5] iommu: Introduce map_sg() as an IOMMU op for IOMMU drivers

Isaac J. Manjarres
2021-01-09T01:51:50Z

Add support for IOMMU drivers to have their own map_sg() callbacks.
This completes the path for having iommu_map_sg() invoke an IOMMU
driver's map_sg() callback, which can then invoke the io-pgtable
map_sg() callback with the entire scatter-gather list, so that it
can be processed entirely in the io-pgtable layer.

For IOMMU drivers that do not provide a callback, the default
implementation of iterating through the scatter-gather list, while
calling iommu_map() will be used.

Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
---
drivers/iommu/iommu.c | 13 +++++++++++++
include/linux/iommu.h | 5 +++++
2 files changed, 18 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 0da0687..46acd5c 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2535,11 +2535,24 @@ static size_t __iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
struct scatterlist *sg, unsigned int nents, int prot,
gfp_t gfp)
{
+ const struct iommu_ops *ops = domain->ops;
size_t len = 0, mapped = 0;
phys_addr_t start;
unsigned int i = 0;
int ret;

+ if (ops->map_sg) {
+ ret = ops->map_sg(domain, iova, sg, nents, prot, gfp, &mapped);
+
+ if (ops->iotlb_sync_map)
+ ops->iotlb_sync_map(domain);
+
+ if (ret)
+ goto out_err;
+
+ return mapped;
+ }
+
while (i <= nents) {
phys_addr_t s_phys = sg_phys(sg);

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 0e40a38..bac7681 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -192,6 +192,8 @@ struct iommu_iotlb_gather {
* @attach_dev: attach device to an iommu domain
* @detach_dev: detach device from an iommu domain
* @map: map a physically contiguous memory region to an iommu domain
+ * @map_sg: map a scatter-gather list of physically contiguous chunks to
+ * an iommu domain.
* @unmap: unmap a physically contiguous memory region from an iommu domain
* @flush_iotlb_all: Synchronously flush all hardware TLBs for this domain
* @iotlb_sync_map: Sync mappings created recently using @map to the hardware
@@ -243,6 +245,9 @@ struct iommu_ops {
void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
int (*map)(struct iommu_domain *domain, unsigned long iova,
phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
+ int (*map_sg)(struct iommu_domain *domain, unsigned long iova,
+ struct scatterlist *sg, unsigned int nents, int prot,
+ gfp_t gfp, size_t *mapped);
size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
size_t size, struct iommu_iotlb_gather *iotlb_gather);
void (*flush_iotlb_all)(struct iommu_domain *domain);