Dear Maxime, Responses inline.
Internal Use - Confidential > -----Original Message----- > From: Maxime Coquelin <[email protected]> > Sent: Tuesday, January 6, 2026 8:37 AM > To: Bathija, Pravin <[email protected]>; [email protected] > Cc: [email protected] > Subject: Re: [PATCH v5 4/4] vhost_user: Function defs for add/rem mem > regions > > > [EXTERNAL EMAIL] > > > > On 11/13/25 1:44 PM, Pravin M Bathija wrote: > > These changes cover the function definition for add/remove memory > > region calls which are invoked on receiving vhost user message from > > vhost user front-end (e.g. Qemu). In our case, in addition to testing > > with qemu front-end, the testing has also been performed with libblkio > > front-end and spdk/dpdk back-end. We did I/O using libblkio based > > device driver, to spdk based drives. There are also changes for > > set_mem_table and new definition for get memory slots. Our changes > > optimize the set memory table call to use common support functions. > > Message get memory slots is how the vhost-user front-end queries the > > vhost-user back-end about the number of memory slots available to be > > registered by the back-end. In addition support function to invalidate > > vring is also defined which is used in add/remove memory region functions. > > > > Signed-off-by: Pravin M Bathija <[email protected]> > > --- > > lib/vhost/vhost_user.c | 249 +++++++++++++++++++++++++++++++++++--- > --- > > 1 file changed, 217 insertions(+), 32 deletions(-) > > > > diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c index > > 7dc21fe42a..d9cf967ba2 100644 > > --- a/lib/vhost/vhost_user.c > > +++ b/lib/vhost/vhost_user.c > > @@ -71,6 +71,9 @@ > VHOST_MESSAGE_HANDLER(VHOST_USER_SET_FEATURES, > vhost_user_set_features, false, t > > VHOST_MESSAGE_HANDLER(VHOST_USER_SET_OWNER, > vhost_user_set_owner, false, true) \ > > VHOST_MESSAGE_HANDLER(VHOST_USER_RESET_OWNER, > vhost_user_reset_owner, false, false) \ > > VHOST_MESSAGE_HANDLER(VHOST_USER_SET_MEM_TABLE, > > vhost_user_set_mem_table, true, true) \ > > +VHOST_MESSAGE_HANDLER(VHOST_USER_GET_MAX_MEM_SLOTS, > > +vhost_user_get_max_mem_slots, false, false) \ > > +VHOST_MESSAGE_HANDLER(VHOST_USER_ADD_MEM_REG, > vhost_user_add_mem_reg, > > +true, true) \ VHOST_MESSAGE_HANDLER(VHOST_USER_REM_MEM_REG, > > +vhost_user_rem_mem_reg, false, true) \ > > VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_BASE, > vhost_user_set_log_base, true, true) \ > > VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_FD, > vhost_user_set_log_fd, true, true) \ > > VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_NUM, > > vhost_user_set_vring_num, false, true) \ @@ -1520,7 +1523,6 @@ > 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; > > @@ -1565,39 +1567,13 @@ 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]; > > @@ -1661,11 +1637,182 @@ 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; > > + rte_free(dev->guest_pages); > > + dev->guest_pages = NULL; > > +close_msg_fds: > > + close_msg_fds(ctx); > > + return RTE_VHOST_MSG_RESULT_ERR; > > +} > > + > > > > -free_guest_pages: > > +static int > > +vhost_user_get_max_mem_slots(struct virtio_net **pdev __rte_unused, > > + struct vhu_msg_context *ctx, > > + int main_fd __rte_unused) > > +{ > > + uint32_t max_mem_slots = VHOST_MEMORY_MAX_NREGIONS; > > + > > + ctx->msg.payload.u64 = (uint64_t)max_mem_slots; > > + ctx->msg.size = sizeof(ctx->msg.payload.u64); > > + ctx->fd_num = 0; > > + > > + return RTE_VHOST_MSG_RESULT_REPLY; > > +} > > + > > +static void > > +dev_invalidate_vrings(struct virtio_net *dev) { > > + uint32_t i; > > + > > + for (i = 0; i < dev->nr_vring; i++) { > > + struct vhost_virtqueue *vq = dev->virtqueue[i]; > > + > > + if (!vq) > > + continue; > > + > > + if (vq->desc || vq->avail || vq->used) { > > + /* vhost_user_lock_all_queue_pairs locked all qps */ > > + VHOST_USER_ASSERT_LOCK(dev, vq, > VHOST_USER_ADD_MEM_REG); > > + > > + /* > > + * If the memory table got updated, the ring addresses > > + * need to be translated again as virtual addresses have > > + * changed. > > + */ > > + vring_invalidate(dev, vq); > > + > > + translate_ring_addresses(&dev, &vq); > > + } > > + } > > +} > > + > > +static int > > +vhost_user_add_mem_reg(struct virtio_net **pdev, > > + struct vhu_msg_context *ctx, > > + int main_fd __rte_unused) > > +{ > > + uint32_t i; > > + struct virtio_net *dev = *pdev; > > + struct VhostUserMemoryRegion *region = > > +&ctx->msg.payload.memory_single.region; > > + > > + /* 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) { > > + VHOST_CONFIG_LOG(dev->ifname, ERR, "too many memory > regions already (%u)", > > + dev- > >mem->nregions); > > + goto close_msg_fds; > > + } > > + > > + /* make sure supplied memory fd present */ > > + if (ctx->fd_num != 1) { > > + VHOST_CONFIG_LOG(dev->ifname, ERR, "fd count makes no > sense (%u)", ctx->fd_num); > > + goto close_msg_fds; > > + } > > + > > + /* Make sure no overlap in guest virtual address space */ > > + if (dev->mem != NULL && dev->mem->nregions > 0) { > > + for (i = 0; i < VHOST_MEMORY_MAX_NREGIONS; i++) { > > + struct rte_vhost_mem_region *current_region = > > +&dev->mem->regions[i]; > > + > > + if (current_region->mmap_size == 0) > > + continue; > > + > > + uint64_t current_region_guest_start = current_region- > >guest_user_addr; > > + uint64_t current_region_guest_end = > current_region_guest_start > > + + > current_region->mmap_size - 1; > > + uint64_t proposed_region_guest_start = region- > >userspace_addr; > > + uint64_t proposed_region_guest_end = > proposed_region_guest_start > > + + region- > >memory_size - 1; > > + bool overlap = false; > > + > > + bool curent_region_guest_start_overlap = > > s/curent/current/ > > > + current_region_guest_start >= > proposed_region_guest_start && > > + current_region_guest_start <= > proposed_region_guest_end; > > + bool curent_region_guest_end_overlap = > > + current_region_guest_end >= > proposed_region_guest_start && > > + current_region_guest_end <= > proposed_region_guest_end; > > Ditto > > > + bool proposed_region_guest_start_overlap = > > + proposed_region_guest_start >= > current_region_guest_start && > > + proposed_region_guest_start <= > current_region_guest_end; > > + bool proposed_region_guest_end_overlap = > > + proposed_region_guest_end >= > current_region_guest_start && > > + proposed_region_guest_end <= > current_region_guest_end; > > + > > + overlap = curent_region_guest_start_overlap > > + || curent_region_guest_end_overlap > > + || proposed_region_guest_start_overlap > > + || proposed_region_guest_end_overlap; > > Couldn't all the above be simplified with something like below? > > overlap = !(proposed_region_guest_end < current_region_guest_start || > proposed_region_guest_start > current_region_guest_end); > You are correct, the above lines of code can be simplified to what you're proposing. I will make the necessary changes, retest and resubmit the patch. > > + > > + if (overlap) { > > + VHOST_CONFIG_LOG(dev->ifname, ERR, > > + "requested memory region overlaps > with another region"); > > + VHOST_CONFIG_LOG(dev->ifname, ERR, > > + "\tRequested region address:0x%" > PRIx64, > > + region->userspace_addr); > > + VHOST_CONFIG_LOG(dev->ifname, ERR, > > + "\tRequested region size:0x%" PRIx64, > > + region->memory_size); > > + VHOST_CONFIG_LOG(dev->ifname, ERR, > > + "\tOverlapping region address:0x%" > PRIx64, > > + current_region->guest_user_addr); > > + VHOST_CONFIG_LOG(dev->ifname, ERR, > > + "\tOverlapping region size:0x%" > PRIx64, > > + current_region->mmap_size); > > + goto close_msg_fds; > > + } > > + > > + } > > + } > > + > > + /* find a new region and set it like memory table set does */ > > + struct rte_vhost_mem_region *reg = NULL; > > + > > + for (i = 0; i < VHOST_MEMORY_MAX_NREGIONS; i++) { > > + if (dev->mem->regions[i].guest_user_addr == 0) { > > + reg = &dev->mem->regions[i]; > > + break; > > + } > > + } > > + if (reg == NULL) { > > + VHOST_CONFIG_LOG(dev->ifname, ERR, "no free memory > region"); > > + goto close_msg_fds; > > + } > > + > > + reg->guest_phys_addr = region->guest_phys_addr; > > + reg->guest_user_addr = region->userspace_addr; > > + reg->size = region->memory_size; > > + reg->fd = ctx->fds[0]; > > + > > + if (vhost_user_mmap_region(dev, reg, region->mmap_offset) < 0) { > > + VHOST_CONFIG_LOG(dev->ifname, ERR, "failed to mmap > region"); > > + goto close_msg_fds; > > + } > > + > > + dev->mem->nregions++; > > + > > + if (dev->async_copy && rte_vfio_is_enabled("vfio")) > > + async_dma_map_region(dev, reg, true); > > + > > + if (vhost_user_postcopy_register(dev, main_fd, ctx) < 0) > > + goto free_mem_table; > > + > > + dev_invalidate_vrings(dev); > > + dump_guest_pages(dev); > > + > > + return RTE_VHOST_MSG_RESULT_OK; > > + > > +free_mem_table: > > + free_all_mem_regions(dev); > > + rte_free(dev->mem); > > + dev->mem = NULL; > > rte_free(dev->guest_pages); > > dev->guest_pages = NULL; > > close_msg_fds: > > @@ -1673,6 +1820,44 @@ vhost_user_set_mem_table(struct virtio_net > **pdev, > > return RTE_VHOST_MSG_RESULT_ERR; > > } > > > > +static int > > +vhost_user_rem_mem_reg(struct virtio_net **pdev __rte_unused, > > + struct vhu_msg_context *ctx __rte_unused, > > + int main_fd __rte_unused) > > +{ > > + uint32_t i; > > + struct virtio_net *dev = *pdev; > > pdev is marked 'unused', it needs to be fixed. > > > + struct VhostUserMemoryRegion *region = > > +&ctx->msg.payload.memory_single.region; > > Same for ctx. > > > + > > + if (dev->mem != NULL && dev->mem->nregions > 0) { > > + for (i = 0; i < VHOST_MEMORY_MAX_NREGIONS; i++) { > > + struct rte_vhost_mem_region *current_region = > > +&dev->mem->regions[i]; > > + > > + if (current_region->guest_user_addr == 0) > > + continue; > > + > > + /* > > + * According to the vhost-user specification: > > + * The memory region to be removed is identified by > its guest address, > > + * user address and size. The mmap offset is ignored. > > + */ > > + if (region->userspace_addr == current_region- > >guest_user_addr > > + && region->guest_phys_addr == > current_region->guest_phys_addr > > + && region->memory_size == current_region- > >size) { > > + if (dev->async_copy && > rte_vfio_is_enabled("vfio")) > > + async_dma_map_region(dev, > current_region, false); > > + dev_invalidate_vrings(dev); > > + free_mem_region(current_region); > > + dev->mem->nregions--; > > + return RTE_VHOST_MSG_RESULT_OK; > > + } > > + } > > + } > > + > > + VHOST_CONFIG_LOG(dev->ifname, ERR, "failed to find region"); > > + return RTE_VHOST_MSG_RESULT_ERR; > > +} > > + > > static bool > > vq_is_ready(struct virtio_net *dev, struct vhost_virtqueue *vq) > > {
