<div dir="ltr"><div dir="ltr"> </div> <div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Wed, May 20, 2026 at 4:20 AM <<a href="mailto:pravin.bathija@dell.com">pravin.bathija@dell.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">From: Pravin M Bathija <<a href="mailto:pravin.bathija@dell.com" target="_blank">pravin.bathija@dell.com</a>> Add support for VHOST_USER_ADD_MEM_REG, VHOST_USER_REM_MEM_REG and VHOST_USER_GET_MAX_MEM_SLOTS. Refactor memory initialization into common helper and add supporting functions for dynamic memory management. Signed-off-by: Pravin M Bathija <<a href="mailto:pravin.bathija@dell.com" target="_blank">pravin.bathija@dell.com</a>> Acked-by: Fengchengwen <<a href="mailto:fengchengwen@huawei.com" target="_blank">fengchengwen@huawei.com</a>> Reviewed-by: Stephen Hemminger <<a href="mailto:stephen@networkplumber.com" target="_blank">stephen@networkplumber.com</a>> Acked-by: Maxime Coquelin <<a href="mailto:maxime.coquelin@redhat.com" target="_blank">maxime.coquelin@redhat.com</a>> --- lib/vhost/vhost_user.c | 255 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 255 insertions(+) diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c index 94fca8b589..522ba1db82 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, true, true) \ </blockquote><div> </div><div>The removal request does not expect FDs in ancillary data.</div><div>It should be:</div><div>VHOST_MESSAGE_HANDLER(VHOST_USER_REM_MEM_REG, vhost_user_rem_mem_reg, false, true)</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> 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) \ @@ -1167,6 +1170,24 @@ add_guest_pages(struct virtio_net *dev, struct rte_vhost_mem_region *reg, return 0; } +static void +remove_guest_pages(struct virtio_net *dev, struct rte_vhost_mem_region *reg) +{ + uint64_t reg_start = reg->host_user_addr; + uint64_t reg_end = reg_start + reg->size; + uint32_t i, j = 0; + + for (i = 0; i < dev->nr_guest_pages; i++) { + if (dev->guest_pages[i].host_user_addr >= reg_start && + dev->guest_pages[i].host_user_addr < reg_end) + continue; + if (j != i) + dev->guest_pages[j] = dev->guest_pages[i]; + j++; + } + dev->nr_guest_pages = j; +} + #ifdef RTE_LIBRTE_VHOST_DEBUG /* TODO: enable it only in debug mode? */ static void @@ -1591,6 +1612,240 @@ vhost_user_set_mem_table(struct virtio_net **pdev, return RTE_VHOST_MSG_RESULT_ERR; } + +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 = max_mem_slots; + ctx->msg.size = sizeof(ctx->msg.payload.u64); + ctx->fd_num = 0; + + return RTE_VHOST_MSG_RESULT_REPLY; +} + +/* + * Invalidate and re-translate all vring addresses after the memory table + * has been modified (add/remove region). + * + * translate_ring_addresses() may call numa_realloc(), which can reallocate + * the device structure. The updated pointer is written back through *pdev + * so callers must refresh their local "dev" afterwards: dev = *pdev. + */ +static void +vhost_user_invalidate_vrings(struct virtio_net **pdev) +{ + struct virtio_net *dev = *pdev; + 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) { + vq_assert_lock(dev, vq); + + vring_invalidate(dev, vq); + + translate_ring_addresses(&dev, &vq); + } + } + + *pdev = dev; +} + +/* + * Macro wrapper that performs the compile-time lock assertion with the + * correct message ID at the call site, then calls the implementation. + */ +#define dev_invalidate_vrings(pdev, id) do { \ + static_assert(id ## _LOCK_ALL_QPS, \ + #id " handler is not declared as locking all queue pairs"); \ + vhost_user_invalidate_vrings(pdev); \ +} while (0) + +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) { + 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 */ + for (i = 0; i < dev->mem->nregions; i++) { + struct rte_vhost_mem_region *cur = &dev->mem->regions[i]; + uint64_t cur_start = cur->guest_user_addr; + uint64_t cur_end = cur_start + cur->size - 1; + uint64_t new_start = region->userspace_addr; + uint64_t new_end = new_start + region->memory_size - 1; + + if (new_end >= cur_start && new_start <= cur_end) { + 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, + cur->guest_user_addr); + VHOST_CONFIG_LOG(dev->ifname, ERR, + "\tOverlapping region size:0x%" PRIx64, + cur->size); + goto close_msg_fds; + } + } + + /* New region goes at the end of the contiguous array */ + struct rte_vhost_mem_region *reg = &dev->mem->regions[dev->mem->nregions]; + + 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]; + ctx->fds[0] = -1; + + if (vhost_user_mmap_region(dev, reg, region->mmap_offset) < 0) { + VHOST_CONFIG_LOG(dev->ifname, ERR, "failed to mmap region"); + if (reg->mmap_addr) { + /* mmap succeeded but a later step (e.g. add_guest_pages) + * failed; undo the mapping and any guest-page entries. + */ + remove_guest_pages(dev, reg); + free_mem_region(reg); + } else { + close(reg->fd); + reg->fd = -1; + } + goto close_msg_fds; + } + + dev->mem->nregions++; + + if (dev->async_copy && rte_vfio_is_enabled("vfio")) { + if (async_dma_map_region(dev, reg, true) < 0) + goto free_new_region_no_dma; + } + + if (dev->postcopy_listening) { + /* + * Cannot use vhost_user_postcopy_register() here because it + * reads ctx->msg.payload.memory (SET_MEM_TABLE layout), but + * ADD_MEM_REG uses the memreg payload. Register the + * single new region directly instead. + */ + if (vhost_user_postcopy_region_register(dev, reg) < 0) + goto free_new_region; + } + + dev_invalidate_vrings(pdev, VHOST_USER_ADD_MEM_REG); + dev = *pdev; + dump_guest_pages(dev); + + /* Reply with the back-end's mapping address per vhost-user spec */ + ctx->msg.payload.memreg.region.userspace_addr = reg->host_user_addr; + ctx->msg.size = sizeof(ctx->msg.payload.memreg); + ctx->fd_num = 0; + + return RTE_VHOST_MSG_RESULT_REPLY; + +free_new_region: + if (dev->async_copy && rte_vfio_is_enabled("vfio")) + async_dma_map_region(dev, reg, false); +free_new_region_no_dma: + remove_guest_pages(dev, reg); + free_mem_region(reg); + dev->mem->nregions--; +close_msg_fds: + close_msg_fds(ctx); + return RTE_VHOST_MSG_RESULT_ERR; +} + +static int +vhost_user_rem_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; + + if (dev->mem == NULL || dev->mem->nregions == 0) { + VHOST_CONFIG_LOG(dev->ifname, ERR, "no memory regions to remove"); + close_msg_fds(ctx); </blockquote><div>Not needed if properly declared.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> + return RTE_VHOST_MSG_RESULT_ERR; + } + + if (validate_msg_fds(dev, ctx, 0) != 0) + return RTE_VHOST_MSG_RESULT_ERR; </blockquote><div> </div><div>With proper declaration, we can remove this check, as it is done in a generic way.</div><div> </div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> + + for (i = 0; i < dev->mem->nregions; i++) { + struct rte_vhost_mem_region *current_region = &dev->mem->regions[i]; + + /* + * According to the vhost-user specification: + * The memory region to be removed is identified by its GPA, + * 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); + remove_guest_pages(dev, current_region); </blockquote><div> </div><div>You are missing the step to clear the IOTLB cache entries matching with this removed region.</div><div>In vhost_user_set_mem_table(), a vhost_user_iotlb_flush_all() call is made,</div><div>but that would be kind of a nuclear option for memory hotplug.</div><div> </div><div>I suggest removing only the entries matching the removed area, something like this:</div><div> if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) vhost_user_iotlb_cache_remove(dev, current_region->guest_phys_addr, current_region->size);</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> + free_mem_region(current_region); + + /* Compact the regions array to keep it contiguous */ + if (i < dev->mem->nregions - 1) { + memmove(&dev->mem->regions[i], + &dev->mem->regions[i + 1], + (dev->mem->nregions - 1 - i) * + sizeof(struct rte_vhost_mem_region)); + memset(&dev->mem->regions[dev->mem->nregions - 1], + 0, sizeof(struct rte_vhost_mem_region)); + } + + dev->mem->nregions--; + dev_invalidate_vrings(pdev, VHOST_USER_REM_MEM_REG); + dev = *pdev; + close_msg_fds(ctx); </blockquote><div><div>And no need to close FDs, are we are now sure none were provided.</div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> + return RTE_VHOST_MSG_RESULT_OK; + } + } + + VHOST_CONFIG_LOG(dev->ifname, ERR, "failed to find region"); + close_msg_fds(ctx); </blockquote><div> </div><div>Same, no more needed.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> + return RTE_VHOST_MSG_RESULT_ERR; +} + static bool vq_is_ready(struct virtio_net *dev, struct vhost_virtqueue *vq) { -- 2.43.0 </blockquote></div></div>