[dpdk-dev] [PATCH 1/4] eal: add new API to register contiguous external memory

[Maxime Coquelin <maxime.coquelin@redhat.com>]

This new API allows to pass a file descriptor while
registering external and contiguous memory in the IOVA space.

This is required for using Virtio-user PMD with application
using external memory for the mbuf's buffers, like Seastar
or VPP.

FD is only attached to the segments if single_file_segment
option is enabled.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_eal/common/eal_common_memory.c  | 75 +++++++++++++++++++++-
 lib/librte_eal/common/include/rte_memory.h | 46 +++++++++++++
 lib/librte_eal/common/malloc_heap.c        | 17 ++++-
 lib/librte_eal/common/malloc_heap.h        |  2 +-
 lib/librte_eal/common/rte_malloc.c         |  2 +-
 lib/librte_eal/rte_eal_version.map         |  3 +
 6 files changed, 141 insertions(+), 4 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index 4a9cc1f19a..7a4b371828 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -772,6 +772,79 @@ rte_memseg_get_fd_offset(const struct rte_memseg *ms, size_t *offset)
 	return ret;
 }
 
+int
+rte_extmem_register_contig(void *va_addr, size_t len, rte_iova_t iova_addr,
+		size_t page_sz, int fd)
+{
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	rte_iova_t *iova_addrs = NULL;
+	unsigned int socket_id, n, i;
+	int ret = 0;
+
+	if (va_addr == NULL || page_sz == 0 || len == 0 ||
+			!rte_is_power_of_2(page_sz) ||
+			RTE_ALIGN(len, page_sz) != len ||
+			((len % page_sz) != 0  ||
+			!rte_is_aligned(va_addr, page_sz))) {
+		rte_errno = EINVAL;
+		return -1;
+	}
+
+	n = len / page_sz;
+	if (iova_addr != 0) {
+		iova_addrs = malloc(n * sizeof(*iova_addrs));
+		if (iova_addrs == NULL) {
+			rte_errno = -ENOMEM;
+			return -1;
+		}
+
+		for (i = 0; i < n; i++)
+			iova_addrs[i] = iova_addr + n * page_sz;
+
+	}
+
+
+	if (fd >= 0 && !internal_config.single_file_segments) {
+		RTE_LOG(INFO, EAL, "FD won't be attached to the external memory," \
+				" requires single file segments\n");
+		fd = -1;
+	}
+	rte_mcfg_mem_write_lock();
+
+	/* make sure the segment doesn't already exist */
+	if (malloc_heap_find_external_seg(va_addr, len) != NULL) {
+		rte_errno = EEXIST;
+		ret = -1;
+		goto unlock;
+	}
+
+	/* get next available socket ID */
+	socket_id = mcfg->next_socket_id;
+	if (socket_id > INT32_MAX) {
+		RTE_LOG(ERR, EAL, "Cannot assign new socket ID's\n");
+		rte_errno = ENOSPC;
+		ret = -1;
+		goto unlock;
+	}
+
+	/* we can create a new memseg */
+	if (malloc_heap_create_external_seg(va_addr, iova_addrs, n,
+			page_sz, "extmem_contig", socket_id, fd) == NULL) {
+		ret = -1;
+		goto unlock;
+	}
+
+	/* memseg list successfully created - increment next socket ID */
+	mcfg->next_socket_id++;
+unlock:
+	rte_mcfg_mem_write_unlock();
+
+	if (iova_addrs != NULL)
+		free(iova_addrs);
+
+	return ret;
+}
+
 int
 rte_extmem_register(void *va_addr, size_t len, rte_iova_t iova_addrs[],
 		unsigned int n_pages, size_t page_sz)
@@ -809,7 +882,7 @@ rte_extmem_register(void *va_addr, size_t len, rte_iova_t iova_addrs[],
 	/* we can create a new memseg */
 	n = len / page_sz;
 	if (malloc_heap_create_external_seg(va_addr, iova_addrs, n,
-			page_sz, "extmem", socket_id) == NULL) {
+			page_sz, "extmem", socket_id, -1) == NULL) {
 		ret = -1;
 		goto unlock;
 	}
diff --git a/lib/librte_eal/common/include/rte_memory.h b/lib/librte_eal/common/include/rte_memory.h
index 3d8d0bd697..e274e47e5e 100644
--- a/lib/librte_eal/common/include/rte_memory.h
+++ b/lib/librte_eal/common/include/rte_memory.h
@@ -451,6 +451,10 @@ rte_memseg_get_fd_offset_thread_unsafe(const struct rte_memseg *ms,
  *   is NULL.
  * @param page_sz
  *   Page size of the underlying memory
+ * @param fd
+ *   File descriptor for the external memory region registered. Must be set to
+ *   -1 if no FD, and ignored if single-segment isn't not used or if iova
+ *   aren't contiguous (iova_addrs != NULL).
  *
  * @return
  *   - 0 on success
@@ -461,6 +465,48 @@ rte_memseg_get_fd_offset_thread_unsafe(const struct rte_memseg *ms,
  */
 __rte_experimental
 int
+rte_extmem_register_contig(void *va_addr, size_t len, rte_iova_t iova_addr,
+		size_t page_sz, int fd);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Register external contiguous memory chunk with DPDK.
+ *
+ * @note Using this API is mutually exclusive with ``rte_malloc`` family of
+ *   API's.
+ *
+ * @note This API will not perform any DMA mapping. It is expected that user
+ *   will do that themselves.
+ *
+ * @note Before accessing this memory in other processes, it needs to be
+ *   attached in each of those processes by calling ``rte_extmem_attach`` in
+ *   each other process.
+ *
+ * @param va_addr
+ *   Start of virtual area to register. Must be aligned by ``page_sz``.
+ * @param len
+ *   Length of virtual area to register. Must be aligned by ``page_sz``.
+ * @param iova_addr
+ *   IOVA address for the contiguous memory chunck. Can be 0, in which case
+ *   page IOVA addresses will be set to RTE_BAD_IOVA.
+ * @param page_sz
+ *   Page size of the underlying memory
+ * @param fd
+ *   File descriptor for the external memory region registered. Must be set to
+ *   -1 if no FD, and ignored if single-segment isn't not used.
+ *
+ * @return
+ *   - 0 on success
+ *   - -1 in case of error, with rte_errno set to one of the following:
+ *     EINVAL - one of the parameters was invalid
+ *     EEXIST - memory chunk is already registered
+ *     ENOSPC - no more space in internal config to store a new memory chunk
+ *     ENOMEM - failed to allocate pages IOVA addresses
+ */
+__rte_experimental
+int
 rte_extmem_register(void *va_addr, size_t len, rte_iova_t iova_addrs[],
 		unsigned int n_pages, size_t page_sz);
 
diff --git a/lib/librte_eal/common/malloc_heap.c b/lib/librte_eal/common/malloc_heap.c
index 842eb9de75..229ab6563c 100644
--- a/lib/librte_eal/common/malloc_heap.c
+++ b/lib/librte_eal/common/malloc_heap.c
@@ -1096,7 +1096,7 @@ destroy_elem(struct malloc_elem *elem, size_t len)
 struct rte_memseg_list *
 malloc_heap_create_external_seg(void *va_addr, rte_iova_t iova_addrs[],
 		unsigned int n_pages, size_t page_sz, const char *seg_name,
-		unsigned int socket_id)
+		unsigned int socket_id, int fd)
 {
 	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
 	char fbarray_name[RTE_FBARRAY_NAME_LEN];
@@ -1153,6 +1153,13 @@ malloc_heap_create_external_seg(void *va_addr, rte_iova_t iova_addrs[],
 	msl->version = 0;
 	msl->external = 1;
 
+	if (fd >= 0) {
+		int list_idx = msl - mcfg->memsegs;
+
+		if (eal_memalloc_set_seg_list_fd(list_idx, fd))
+			RTE_LOG(ERR, EAL, "Failed to set segment list FD\n");
+	}
+
 	return msl;
 }
 
@@ -1202,10 +1209,18 @@ malloc_heap_find_external_seg(void *va_addr, size_t len)
 int
 malloc_heap_destroy_external_seg(struct rte_memseg_list *msl)
 {
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	int list_idx;
+
 	/* destroy the fbarray backing this memory */
 	if (rte_fbarray_destroy(&msl->memseg_arr) < 0)
 		return -1;
 
+	list_idx = msl - mcfg->memsegs;
+	if (eal_memalloc_set_seg_list_fd(list_idx, -1))
+		RTE_LOG(ERR, EAL, "Failed to reset segment list FD\n");
+
+
 	/* reset the memseg list */
 	memset(msl, 0, sizeof(*msl));
 
diff --git a/lib/librte_eal/common/malloc_heap.h b/lib/librte_eal/common/malloc_heap.h
index 772736b53f..438ce908de 100644
--- a/lib/librte_eal/common/malloc_heap.h
+++ b/lib/librte_eal/common/malloc_heap.h
@@ -65,7 +65,7 @@ malloc_heap_destroy(struct malloc_heap *heap);
 struct rte_memseg_list *
 malloc_heap_create_external_seg(void *va_addr, rte_iova_t iova_addrs[],
 		unsigned int n_pages, size_t page_sz, const char *seg_name,
-		unsigned int socket_id);
+		unsigned int socket_id, int fd);
 
 struct rte_memseg_list *
 malloc_heap_find_external_seg(void *va_addr, size_t len);
diff --git a/lib/librte_eal/common/rte_malloc.c b/lib/librte_eal/common/rte_malloc.c
index d6026a2b17..aa19b0517f 100644
--- a/lib/librte_eal/common/rte_malloc.c
+++ b/lib/librte_eal/common/rte_malloc.c
@@ -389,7 +389,7 @@ rte_malloc_heap_memory_add(const char *heap_name, void *va_addr, size_t len,
 	n = len / page_sz;
 
 	msl = malloc_heap_create_external_seg(va_addr, iova_addrs, n, page_sz,
-			heap_name, heap->socket_id);
+			heap_name, heap->socket_id, -1);
 	if (msl == NULL) {
 		ret = -1;
 		goto unlock;
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index e38d02530c..ddcb4b0512 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -332,4 +332,7 @@ EXPERIMENTAL {
 	# added in 19.11
 	rte_log_get_stream;
 	rte_mcfg_get_single_file_segments;
+
+	# added in 20.02
+	rte_extmem_register_contig;
 };
-- 
2.21.0