This helper iterates through the SG list to find the best page size to use
from a bitmap of HW supported page sizes. Drivers that support multiple
page sizes, but not mixed sizes in an MR can use this API.
Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Gal Pressman <galpress@xxxxxxxxxx>
Signed-off-by: Shiraz Saleem <shiraz.saleem@xxxxxxxxx>
---
drivers/infiniband/core/umem.c | 51 ++++++++++++++++++++++++++++++++++++++++++
include/rdma/ib_umem.h | 9 ++++++++
include/rdma/ib_verbs.h | 24 ++++++++++++++++++++
3 files changed, 84 insertions(+)
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 7e912a9..2534ddd 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -127,6 +127,57 @@ static struct scatterlist *ib_umem_add_sg_table(struct scatterlist *sg,
}
/**
+ * ib_umem_find_best_pgsz - Find best HW page size to use for this MR
+ *
+ * @umem: umem struct
+ * @pgsz_bitmap: bitmap of HW supported page sizes
+ * @virt: IOVA
+ *
+ * This helper is intended for HW that support multiple page
+ * sizes but can do only a single page size in an MR.
+ *
+ * Returns 0 if the umem requires page sizes not supported by
+ * the driver to be mapped. Drivers always supporting PAGE_SIZE
+ * or smaller will never see a 0 result.
+ */
+unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
+ unsigned long pgsz_bitmap,
+ unsigned long virt)
+{
+ struct scatterlist *sg;
+ unsigned int best_pg_bit;
+ unsigned long va, pgoff;
+ dma_addr_t mask;
+ int i;
+
+ /* At minimum, drivers must support PAGE_SIZE or smaller */
+ if (WARN_ON(!(pgsz_bitmap & GENMASK(PAGE_SHIFT, 0))))
+ return 0;
+
+ va = virt;
+ /* max page size not to exceed MR length */
+ mask = roundup_pow_of_two(umem->length);
+ /* offset into first SGL */
+ pgoff = umem->address & ~PAGE_MASK;
+
+ for_each_sg(umem->sg_head.sgl, sg, umem->nmap, i) {
+ /* Walk SGL and reduce max page size if VA/PA bits differ
+ * for any address.
+ */
+ mask |= (sg_dma_address(sg) + pgoff) ^ va;
+ if (i && i != (umem->nmap - 1))
+ /* restrict by length as well for interior SGEs */
+ mask |= sg_dma_len(sg);
+ va += sg_dma_len(sg) - pgoff;
+ pgoff = 0;
+ }
+ best_pg_bit = rdma_find_pg_bit(mask, pgsz_bitmap);
+
+ return BIT_ULL(best_pg_bit);
+}
+EXPORT_SYMBOL(ib_umem_find_best_pgsz);
+
+/**
* ib_umem_get - Pin and DMA map userspace memory.
*
* If access flags indicate ODP memory, avoid pinning. Instead, stores
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index b13a2e9..917b687 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -87,6 +87,9 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
int ib_umem_page_count(struct ib_umem *umem);
int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
size_t length);
+unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
+ unsigned long pgsz_bitmap,
+ unsigned long virt);
#else /* CONFIG_INFINIBAND_USER_MEM */
@@ -104,6 +107,12 @@ static inline int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offs
size_t length) {
return -EINVAL;
}
+static inline int ib_umem_find_best_pgsz(struct ib_umem *umem,
+ unsigned long pgsz_bitmap,
+ unsigned long virt) {
+ return -EINVAL;
+}
+
#endif /* CONFIG_INFINIBAND_USER_MEM */
#endif /* IB_UMEM_H */
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index de8724e..5391c24 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -3235,6 +3235,30 @@ static inline bool rdma_cap_read_inv(struct ib_device *dev, u32 port_num)
return rdma_protocol_iwarp(dev, port_num);
}
+/**
+ * rdma_find_pg_bit - Find page bit given address and HW supported page sizes
+ *
+ * @addr: address
+ * @pgsz_bitmap: bitmap of HW supported page sizes
+ */
+static inline unsigned int rdma_find_pg_bit(unsigned long addr,
+ unsigned long pgsz_bitmap)
+{
+ unsigned long align;
+ unsigned long pgsz;
+
+ align = addr & -addr;
+
+ /* Find page bit such that addr is aligned to the highest supported
+ * HW page size
+ */
+ pgsz = pgsz_bitmap & ~(-align << 1);
+ if (!pgsz)
+ return __ffs(pgsz_bitmap);
+
+ return __fls(pgsz);
+}
+
int ib_set_vf_link_state(struct ib_device *device, int vf, u8 port,
int state);
int ib_get_vf_config(struct ib_device *device, int vf, u8 port,
--
1.8.3.1
