From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jianfeng Tan Subject: [PATCH] vhost: fix segfault as handle set_mem_table message Date: Wed, 15 Nov 2017 11:41:08 +0000 Message-ID: <1510746068-143223-1-git-send-email-jianfeng.tan@intel.com> Cc: Jianfeng Tan , stable@dpdk.org, Yuanhan Liu , Maxime Coquelin , Yi Yang To: dev@dpdk.org Return-path: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" In a running VM, operations (like device attach/detach) will trigger the QEMU to resend set_mem_table to vhost-user backend. DPDK vhost-user handles this message rudely by unmap all existing regions and map new ones. This might lead to segfault if there is pmd thread just trying to touch those unmapped memory regions. But for most cases, except VM memory hotplug, QEMU still sends the set_mem_table message even the memory regions are not changed as QEMU vhost-user filters out those not backed by file (fd > 0). To fix this case, we add a check in the handler to see if the memory regions are really changed; if not, we just keep old memory regions. Fixes: 8f972312b8f4 ("vhost: support vhost-user") CC: stable@dpdk.org CC: Yuanhan Liu CC: Maxime Coquelin Reported-by: Yang Zhang Reported-by: Xin Long Signed-off-by: Yi Yang Signed-off-by: Jianfeng Tan --- lib/librte_vhost/vhost_user.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c index f4c7ce4..2291929 100644 --- a/lib/librte_vhost/vhost_user.c +++ b/lib/librte_vhost/vhost_user.c @@ -573,6 +573,29 @@ dump_guest_pages(struct virtio_net *dev) #define dump_guest_pages(dev) #endif +static bool vhost_memory_changed(struct VhostUserMemory *new, + struct rte_vhost_memory *old) +{ + uint32_t i; + + if (new->nregions != old->nregions) + return true; + + for (i = 0; i < new->nregions; ++i) { + VhostUserMemoryRegion *new_r = &new->regions[i]; + struct rte_vhost_mem_region *old_r = &old->regions[i]; + + if (new_r->guest_phys_addr != old_r->guest_phys_addr) + return true; + if (new_r->memory_size != old_r->size) + return true; + if (new_r->userspace_addr != old_r->guest_user_addr) + return true; + } + + return false; +} + static int vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg) { @@ -585,6 +608,16 @@ vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg) uint32_t i; int fd; + if (dev->mem && !vhost_memory_changed(&memory, dev->mem)) { + RTE_LOG(INFO, VHOST_CONFIG, + "(%d) memory regions not changed\n", dev->vid); + + for (i = 0; i < memory.nregions; i++) + close(pmsg->fds[i]); + + return 0; + } + if (dev->mem) { free_mem_region(dev); rte_free(dev->mem); -- 2.7.4