RDMA: Add ib_virt_dma_to_page()

Make it clearer what is going on by adding a function to go back from the
"virtual" dma_addr to a kva and another to a struct page. This is used in the
ib_uses_virt_dma() style drivers (siw, rxe, hfi, qib).

Call them instead of a naked casting and  virt_to_page() when working with dma_addr
values encoded by the various ib_map functions.

This also fixes the virt_to_page() casting problem Linus Walleij has been
chasing.

Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/0-v2-05ea785520ed+10-ib_virt_page_jgg@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 949cf4ffc536..1e7774ac808f 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -4036,6 +4036,31 @@ static inline bool ib_dma_pci_p2p_dma_supported(struct ib_device *dev)
 }
 
 /**
+ * ib_virt_dma_to_ptr - Convert a dma_addr to a kernel pointer
+ * @dma_addr: The DMA address
+ *
+ * Used by ib_uses_virt_dma() devices to get back to the kernel pointer after
+ * going through the dma_addr marshalling.
+ */
+static inline void *ib_virt_dma_to_ptr(u64 dma_addr)
+{
+	/* virt_dma mode maps the kvs's directly into the dma addr */
+	return (void *)(uintptr_t)dma_addr;
+}
+
+/**
+ * ib_virt_dma_to_page - Convert a dma_addr to a struct page
+ * @dma_addr: The DMA address
+ *
+ * Used by ib_uses_virt_dma() device to get back to the struct page after going
+ * through the dma_addr marshalling.
+ */
+static inline struct page *ib_virt_dma_to_page(u64 dma_addr)
+{
+	return virt_to_page(ib_virt_dma_to_ptr(dma_addr));
+}
+
+/**
  * ib_dma_mapping_error - check a DMA addr for error
  * @dev: The device for which the dma_addr was created
  * @dma_addr: The DMA address to check