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Subject[PATCH 2/9] iommu/dma-iommu: Add function to flush any cached not present IOTLB entries
Date
Both the AMD and Intel drivers can cache not present IOTLB entries. To
convert these drivers to the dma-iommu api we need a generic way to
flush the NP cache. IOMMU drivers which have a NP cache can implement
the .flush_np_cache function in the iommu ops struct. I will implement
.flush_np_cache for both the Intel and AMD drivers in later patches.

The Intel np-cache is described here:
https://software.intel.com/sites/default/files/managed/c5/15/vt-directed-io-spec.pdf#G7.66452

And the AMD np-cache is described here:
https://developer.amd.com/wordpress/media/2012/10/34434-IOMMU-Rev_1.26_2-11-09.pdf#page=63

Signed-off-by: Tom Murphy <tmurphy@arista.com>
---
drivers/iommu/dma-iommu.c | 10 ++++++++++
include/linux/iommu.h | 3 +++
2 files changed, 13 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 1a4bff3f8427..cc5da30d6e58 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -594,6 +594,9 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
< size)
goto out_free_sg;

+ if (domain->ops->flush_np_cache)
+ domain->ops->flush_np_cache(domain, iova, size);
+
*handle = iova;
sg_free_table(&sgt);
return pages;
@@ -652,6 +655,10 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
iommu_dma_free_iova(cookie, iova, size);
return DMA_MAPPING_ERROR;
}
+
+ if (domain->ops->flush_np_cache)
+ domain->ops->flush_np_cache(domain, iova, size);
+
return iova + iova_off;
}

@@ -812,6 +819,9 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
if (iommu_map_sg_atomic(domain, iova, sg, nents, prot) < iova_len)
goto out_free_iova;

+ if (domain->ops->flush_np_cache)
+ domain->ops->flush_np_cache(domain, iova, iova_len);
+
return __finalise_sg(dev, sg, nents, iova);

out_free_iova:
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 75559918d9bd..47ff8d731d6a 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -173,6 +173,7 @@ struct iommu_resv_region {
* @iotlb_sync_map: Sync mappings created recently using @map to the hardware
* @iotlb_sync: Flush all queued ranges from the hardware TLBs and empty flush
* queue
+ * @flush_np_cache: Flush the non present entry cache
* @iova_to_phys: translate iova to physical address
* @add_device: add device to iommu grouping
* @remove_device: remove device from iommu grouping
@@ -209,6 +210,8 @@ struct iommu_ops {
unsigned long iova, size_t size);
void (*iotlb_sync_map)(struct iommu_domain *domain);
void (*iotlb_sync)(struct iommu_domain *domain);
+ void (*flush_np_cache)(struct iommu_domain *domain,
+ unsigned long iova, size_t size);
phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
int (*add_device)(struct device *dev);
void (*remove_device)(struct device *dev);
--
2.17.1
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