[PATCH v1 03/10] PCI/P2PDMA: Simplify bus address mapping API

Leon Romanovsky
2025-08-04T13:01:05Z

From: Leon Romanovsky <leonro@nvidia.com>

Update the pci_p2pdma_bus_addr_map() function to take a direct pointer
to the p2pdma_provider structure instead of the pci_p2pdma_map_state.
This simplifies the API by removing the need for callers to extract
the provider from the state structure.

The change updates all callers across the kernel (block layer, IOMMU,
DMA direct, and HMM) to pass the provider pointer directly, making
the code more explicit and reducing unnecessary indirection. This
also removes the runtime warning check since callers now have direct
control over which provider they use.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
block/blk-mq-dma.c | 2 +-
drivers/iommu/dma-iommu.c | 4 ++--
include/linux/pci-p2pdma.h | 7 +++----
kernel/dma/direct.c | 4 ++--
mm/hmm.c | 2 +-
5 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c
index d415088ed9fd2..430e51ec494a6 100644
--- a/block/blk-mq-dma.c
+++ b/block/blk-mq-dma.c
@@ -79,7 +79,7 @@ static inline bool blk_can_dma_map_iova(struct request *req,

static bool blk_dma_map_bus(struct blk_dma_iter *iter, struct phys_vec *vec)
{
- iter->addr = pci_p2pdma_bus_addr_map(&iter->p2pdma, vec->paddr);
+ iter->addr = pci_p2pdma_bus_addr_map(iter->p2pdma.mem, vec->paddr);
iter->len = vec->len;
return true;
}
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 69f85209be7ab..7c1c25ffb804d 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1439,8 +1439,8 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
* as a bus address, __finalise_sg() will copy the dma
* address into the output segment.
*/
- s->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state,
- sg_phys(s));
+ s->dma_address = pci_p2pdma_bus_addr_map(
+ p2pdma_state.mem, sg_phys(s));
sg_dma_len(s) = sg->length;
sg_dma_mark_bus_address(s);
continue;
diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
index 27a2c399f47da..eef96636c67e6 100644
--- a/include/linux/pci-p2pdma.h
+++ b/include/linux/pci-p2pdma.h
@@ -186,16 +186,15 @@ pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
/**
* pci_p2pdma_bus_addr_map - Translate a physical address to a bus address
* for a PCI_P2PDMA_MAP_BUS_ADDR transfer.
- * @state: P2P state structure
+ * @provider: P2P provider structure
* @paddr: physical address to map
*
* Map a physically contiguous PCI_P2PDMA_MAP_BUS_ADDR transfer.
*/
static inline dma_addr_t
-pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
+pci_p2pdma_bus_addr_map(struct p2pdma_provider *provider, phys_addr_t paddr)
{
- WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
- return paddr + state->mem->bus_offset;
+ return paddr + provider->bus_offset;
}

#endif /* _LINUX_PCI_P2P_H */
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 1062caac47e7b..3e058c99fe856 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -484,8 +484,8 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
}
break;
case PCI_P2PDMA_MAP_BUS_ADDR:
- sg->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state,
- sg_phys(sg));
+ sg->dma_address = pci_p2pdma_bus_addr_map(
+ p2pdma_state.mem, sg_phys(sg));
sg_dma_mark_bus_address(sg);
continue;
default:
diff --git a/mm/hmm.c b/mm/hmm.c
index 6556c0e074ba8..012b78688fa18 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -751,7 +751,7 @@ dma_addr_t hmm_dma_map_pfn(struct device *dev, struct hmm_dma_map *map,
break;
case PCI_P2PDMA_MAP_BUS_ADDR:
pfns[idx] |= HMM_PFN_P2PDMA_BUS | HMM_PFN_DMA_MAPPED;
- return pci_p2pdma_bus_addr_map(p2pdma_state, paddr);
+ return pci_p2pdma_bus_addr_map(p2pdma_state->mem, paddr);
default:
return DMA_MAPPING_ERROR;
}
--
2.50.1