[PATCH v15 3/5] vhost: refactor memory helper functions

[pravin.bathija at dell.com]

From: Pravin M Bathija <pravin.bathija at dell.com>

- Extract reusable helper routines for vhost-user backend memory
operations.
- Split DMA map/unmap into per-region logic.
- Decouple and rework memory region free routines.
- Iterate over VHOST_MEMORY_MAX_NREGIONS uniformly
across related functions to simplify code reuse

Signed-off-by: Pravin M Bathija <pravin.bathija at dell.com>
Reviewed-by: Stephen Hemminger <stephen at networkplumber.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 lib/vhost/vhost_user.c | 172 ++++++++++++++++++++++++++---------------
 1 file changed, 110 insertions(+), 62 deletions(-)

diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 4bfb13fb98..94fca8b589 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -171,20 +171,27 @@ get_blk_size(int fd)
 	return ret == -1 ? (uint64_t)-1 : (uint64_t)stat.st_blksize;
 }
 
-static void
-async_dma_map(struct virtio_net *dev, bool do_map)
+static int
+async_dma_map_region(struct virtio_net *dev, struct rte_vhost_mem_region *reg, bool do_map)
 {
-	int ret = 0;
 	uint32_t i;
-	struct guest_page *page;
+	int ret;
+	uint64_t reg_start = reg->host_user_addr;
+	uint64_t reg_end = reg_start + reg->size;
 
-	if (do_map) {
-		for (i = 0; i < dev->nr_guest_pages; i++) {
-			page = &dev->guest_pages[i];
+	for (i = 0; i < dev->nr_guest_pages; i++) {
+		struct guest_page *page = &dev->guest_pages[i];
+
+		/* Only process pages belonging to this region */
+		if (page->host_user_addr < reg_start ||
+		    page->host_user_addr >= reg_end)
+			continue;
+
+		if (do_map) {
 			ret = rte_vfio_container_dma_map(RTE_VFIO_DEFAULT_CONTAINER_FD,
-							 page->host_user_addr,
-							 page->host_iova,
-							 page->size);
+					page->host_user_addr,
+					page->host_iova,
+					page->size);
 			if (ret) {
 				/*
 				 * DMA device may bind with kernel driver, in this case,
@@ -199,33 +206,57 @@ async_dma_map(struct virtio_net *dev, bool do_map)
 				 * normal case in async path. This is a workaround.
 				 */
 				if (rte_errno == ENODEV)
-					return;
+					return 0;
 
 				/* DMA mapping errors won't stop VHOST_USER_SET_MEM_TABLE. */
 				VHOST_CONFIG_LOG(dev->ifname, ERR, "DMA engine map failed");
+				return -1;
 			}
-		}
-
-	} else {
-		for (i = 0; i < dev->nr_guest_pages; i++) {
-			page = &dev->guest_pages[i];
+		} else {
 			ret = rte_vfio_container_dma_unmap(RTE_VFIO_DEFAULT_CONTAINER_FD,
-							   page->host_user_addr,
-							   page->host_iova,
-							   page->size);
+					page->host_user_addr,
+					page->host_iova,
+					page->size);
 			if (ret) {
 				/* like DMA map, ignore the kernel driver case when unmap. */
 				if (rte_errno == EINVAL)
-					return;
+					return 0;
 
 				VHOST_CONFIG_LOG(dev->ifname, ERR, "DMA engine unmap failed");
+				return -1;
 			}
 		}
 	}
+
+	return 0;
+}
+
+static void
+async_dma_map(struct virtio_net *dev, bool do_map)
+{
+	uint32_t i;
+	struct rte_vhost_mem_region *reg;
+
+	for (i = 0; i < VHOST_MEMORY_MAX_NREGIONS; i++) {
+		reg = &dev->mem->regions[i];
+		if (reg->host_user_addr == 0)
+			continue;
+		async_dma_map_region(dev, reg, do_map);
+	}
 }
 
 static void
-free_mem_region(struct virtio_net *dev)
+free_mem_region(struct rte_vhost_mem_region *reg)
+{
+	if (reg != NULL && reg->mmap_addr) {
+		munmap(reg->mmap_addr, reg->mmap_size);
+		close(reg->fd);
+		memset(reg, 0, sizeof(struct rte_vhost_mem_region));
+	}
+}
+
+static void
+free_all_mem_regions(struct virtio_net *dev)
 {
 	uint32_t i;
 	struct rte_vhost_mem_region *reg;
@@ -236,12 +267,10 @@ free_mem_region(struct virtio_net *dev)
 	if (dev->async_copy && rte_vfio_is_enabled("vfio"))
 		async_dma_map(dev, false);
 
-	for (i = 0; i < dev->mem->nregions; i++) {
+	for (i = 0; i < VHOST_MEMORY_MAX_NREGIONS; i++) {
 		reg = &dev->mem->regions[i];
-		if (reg->host_user_addr) {
-			munmap(reg->mmap_addr, reg->mmap_size);
-			close(reg->fd);
-		}
+		if (reg->mmap_addr)
+			free_mem_region(reg);
 	}
 }
 
@@ -255,7 +284,7 @@ vhost_backend_cleanup(struct virtio_net *dev)
 		vdpa_dev->ops->dev_cleanup(dev->vid);
 
 	if (dev->mem) {
-		free_mem_region(dev);
+		free_all_mem_regions(dev);
 		rte_free(dev->mem);
 		dev->mem = NULL;
 	}
@@ -704,7 +733,7 @@ numa_realloc(struct virtio_net **pdev, struct vhost_virtqueue **pvq)
 	vhost_devices[dev->vid] = dev;
 
 	mem_size = sizeof(struct rte_vhost_memory) +
-		sizeof(struct rte_vhost_mem_region) * dev->mem->nregions;
+		sizeof(struct rte_vhost_mem_region) * VHOST_MEMORY_MAX_NREGIONS;
 	mem = rte_realloc_socket(dev->mem, mem_size, 0, node);
 	if (!mem) {
 		VHOST_CONFIG_LOG(dev->ifname, ERR,
@@ -808,8 +837,10 @@ hua_to_alignment(struct rte_vhost_memory *mem, void *ptr)
 	uint32_t i;
 	uintptr_t hua = (uintptr_t)ptr;
 
-	for (i = 0; i < mem->nregions; i++) {
+	for (i = 0; i < VHOST_MEMORY_MAX_NREGIONS; i++) {
 		r = &mem->regions[i];
+		if (r->host_user_addr == 0)
+			continue;
 		if (hua >= r->host_user_addr &&
 			hua < r->host_user_addr + r->size) {
 			return get_blk_size(r->fd);
@@ -1382,6 +1413,52 @@ vhost_user_mmap_region(struct virtio_net *dev,
 	return 0;
 }
 
+static int
+vhost_user_initialize_memory(struct virtio_net **pdev)
+{
+	struct virtio_net *dev = *pdev;
+	int numa_node = SOCKET_ID_ANY;
+
+	if (dev->mem != NULL) {
+		VHOST_CONFIG_LOG(dev->ifname, ERR,
+			"memory already initialized, free it first");
+		return -1;
+	}
+
+	/*
+	 * If VQ 0 has already been allocated, try to allocate on the same
+	 * NUMA node. It can be reallocated later in numa_realloc().
+	 */
+	if (dev->nr_vring > 0)
+		numa_node = dev->virtqueue[0]->numa_node;
+
+	dev->nr_guest_pages = 0;
+	if (dev->guest_pages == NULL) {
+		dev->max_guest_pages = 8;
+		dev->guest_pages = rte_zmalloc_socket(NULL,
+					dev->max_guest_pages *
+					sizeof(struct guest_page),
+					RTE_CACHE_LINE_SIZE,
+					numa_node);
+		if (dev->guest_pages == NULL) {
+			VHOST_CONFIG_LOG(dev->ifname, ERR,
+				"failed to allocate memory for dev->guest_pages");
+			return -1;
+		}
+	}
+
+	dev->mem = rte_zmalloc_socket("vhost-mem-table", sizeof(struct rte_vhost_memory) +
+		sizeof(struct rte_vhost_mem_region) * VHOST_MEMORY_MAX_NREGIONS, 0, numa_node);
+	if (dev->mem == NULL) {
+		VHOST_CONFIG_LOG(dev->ifname, ERR, "failed to allocate memory for dev->mem");
+		rte_free(dev->guest_pages);
+		dev->guest_pages = NULL;
+		return -1;
+	}
+
+	return 0;
+}
+
 static int
 vhost_user_set_mem_table(struct virtio_net **pdev,
 			struct vhu_msg_context *ctx,
@@ -1390,7 +1467,6 @@ vhost_user_set_mem_table(struct virtio_net **pdev,
 	struct virtio_net *dev = *pdev;
 	struct VhostUserMemory *memory = &ctx->msg.payload.memory;
 	struct rte_vhost_mem_region *reg;
-	int numa_node = SOCKET_ID_ANY;
 	uint64_t mmap_offset;
 	uint32_t i;
 	bool async_notify = false;
@@ -1435,39 +1511,13 @@ vhost_user_set_mem_table(struct virtio_net **pdev,
 		if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
 			vhost_user_iotlb_flush_all(dev);
 
-		free_mem_region(dev);
+		free_all_mem_regions(dev);
 		rte_free(dev->mem);
 		dev->mem = NULL;
 	}
 
-	/*
-	 * If VQ 0 has already been allocated, try to allocate on the same
-	 * NUMA node. It can be reallocated later in numa_realloc().
-	 */
-	if (dev->nr_vring > 0)
-		numa_node = dev->virtqueue[0]->numa_node;
-
-	dev->nr_guest_pages = 0;
-	if (dev->guest_pages == NULL) {
-		dev->max_guest_pages = 8;
-		dev->guest_pages = rte_zmalloc_socket(NULL,
-					dev->max_guest_pages *
-					sizeof(struct guest_page),
-					RTE_CACHE_LINE_SIZE,
-					numa_node);
-		if (dev->guest_pages == NULL) {
-			VHOST_CONFIG_LOG(dev->ifname, ERR,
-				"failed to allocate memory for dev->guest_pages");
-			goto close_msg_fds;
-		}
-	}
-
-	dev->mem = rte_zmalloc_socket("vhost-mem-table", sizeof(struct rte_vhost_memory) +
-		sizeof(struct rte_vhost_mem_region) * memory->nregions, 0, numa_node);
-	if (dev->mem == NULL) {
-		VHOST_CONFIG_LOG(dev->ifname, ERR, "failed to allocate memory for dev->mem");
-		goto free_guest_pages;
-	}
+	if (vhost_user_initialize_memory(pdev) < 0)
+		goto close_msg_fds;
 
 	for (i = 0; i < memory->nregions; i++) {
 		reg = &dev->mem->regions[i];
@@ -1531,11 +1581,9 @@ vhost_user_set_mem_table(struct virtio_net **pdev,
 	return RTE_VHOST_MSG_RESULT_OK;
 
 free_mem_table:
-	free_mem_region(dev);
+	free_all_mem_regions(dev);
 	rte_free(dev->mem);
 	dev->mem = NULL;
-
-free_guest_pages:
 	rte_free(dev->guest_pages);
 	dev->guest_pages = NULL;
 close_msg_fds:
-- 
2.43.0