|SUCCESS| [v14,5/5] vhost: enable configure memory slots

[dpdklab at iol.unh.edu]

Test-Label: ai-code-review
Test-Status: SUCCESS
https://dpdk.org/patch/164179

_AI Code Review_

=== Patch Review: series.patch (via Claude) ===
Review date: 2026-05-20

git sha: series.patch (multiple commits)

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

Subject: [PATCH v14 1/5] vhost: add user to mailmap and define to vhost hdr
         [PATCH v14 2/5] vhost: header defines for add/rem mem region
         [PATCH v14 3/5] vhost: refactor memory helper functions
         [PATCH v14 4/5] vhost: add mem region add/remove handlers
         [PATCH v14 5/5] vhost: enable configure memory slots

This patch series adds support for dynamic memory region management in
vhost-user backend, including refactoring of memory operations and new
handlers for memory region add/remove functionality.

> diff --git a/.mailmap b/.mailmap
> index 0e0d83e1c6..cc44e27036 100644
> --- a/.mailmap
> +++ b/.mailmap
> @@ -1295,6 +1295,7 @@ Prateek Agarwal <prateekag at cse.iitb.ac.in>
>  Prathisna Padmasanan <prathisna.padmasanan at intel.com>
>  Praveen Kaligineedi <pkaligineedi at google.com>
>  Praveen Shetty <praveen.shetty at intel.com>
> +Pravin M Bathija <pravin.bathija at dell.com>
>  Pravin Pathak <pravin.pathak.dev at gmail.com> <pravin.pathak at intel.com>
>  Prince Takkar <ptakkar at marvell.com>
>  Priyalee Kushwaha <priyalee.kushwaha at intel.com>
> diff --git a/lib/vhost/rte_vhost.h b/lib/vhost/rte_vhost.h
> index 2f7c4c0080..a7f9700538 100644
> --- a/lib/vhost/rte_vhost.h
> +++ b/lib/vhost/rte_vhost.h
> @@ -109,6 +109,10 @@ extern "C" {
>  #define VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD 12
>  #endif
>  
> +#ifndef VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS
> +#define VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS 15
> +#endif
> +
>  #ifndef VHOST_USER_PROTOCOL_F_STATUS
>  #define VHOST_USER_PROTOCOL_F_STATUS 16
>  #endif

[ ... ]

> diff --git a/lib/vhost/vhost_user.h b/lib/vhost/vhost_user.h
> index ef486545ba..6435816534 100644
> --- a/lib/vhost/vhost_user.h
> +++ b/lib/vhost/vhost_user.h
> @@ -67,6 +67,9 @@ typedef enum VhostUserRequest {
>  	VHOST_USER_POSTCOPY_END = 30,
>  	VHOST_USER_GET_INFLIGHT_FD = 31,
>  	VHOST_USER_SET_INFLIGHT_FD = 32,
> +	VHOST_USER_GET_MAX_MEM_SLOTS = 36,
> +	VHOST_USER_ADD_MEM_REG = 37,
> +	VHOST_USER_REM_MEM_REG = 38,
>  	VHOST_USER_SET_STATUS = 39,
>  	VHOST_USER_GET_STATUS = 40,
>  } VhostUserRequest;
> @@ -91,6 +94,11 @@ typedef struct VhostUserMemory {
>  	VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
>  } VhostUserMemory;
>  
> +typedef struct VhostUserMemRegMsg {
> +	uint64_t padding;
> +	VhostUserMemoryRegion region;
> +} VhostUserMemRegMsg;
> +
>  typedef struct VhostUserLog {
>  	uint64_t mmap_size;
>  	uint64_t mmap_offset;
> @@ -186,6 +194,7 @@ typedef struct __rte_packed_begin VhostUserMsg {
>  		struct vhost_vring_state state;
>  		struct vhost_vring_addr addr;
>  		VhostUserMemory memory;
> +		VhostUserMemRegMsg memreg;
>  		VhostUserLog    log;
>  		struct vhost_iotlb_msg iotlb;
>  		VhostUserCryptoSessionParam crypto_session;

[ ... ]

> 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);

Does this change in argument alignment preserve the original intent, or
could indentation be inconsistent with other rte_vfio_container_dma_map
calls in the codebase?

[ ... ]

> @@ -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);
>  	}
>  }

After free_mem_region(reg) is called, does reg still point to valid
memory in the regions array, and could subsequent iterations in
free_all_mem_regions() safely use this potentially-cleared memory?

[ ... ]

> @@ -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;

Does this access dev->virtqueue[0] safely when nr_vring > 0 but
virtqueue[0] could be NULL?

> +
> +	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;

After freeing dev->guest_pages here, does the cleanup in error paths
properly reset dev->max_guest_pages to zero, or could this lead to
inconsistent state?

> +		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:

[ ... ]

> +static int
> +vhost_user_add_mem_reg(struct virtio_net **pdev,
> +			struct vhu_msg_context *ctx,
> +			int main_fd __rte_unused)
> +{
> +	struct VhostUserMemoryRegion *region = &ctx->msg.payload.memreg.region;
> +	struct virtio_net *dev = *pdev;
> +	uint32_t i;
> +
> +	/* convert first region add to normal memory table set */
> +	if (dev->mem == NULL) {
> +		if (vhost_user_initialize_memory(pdev) < 0)
> +			goto close_msg_fds;
> +	}
> +
> +	/* make sure new region will fit */
> +	if (dev->mem->nregions >= VHOST_MEMORY_MAX_NREGIONS) {
> +