vhost: send userfault range addresses back to Qemu

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index d17c3b0..8890abb 100644 (file)
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -79,6 +79,9 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
        [VHOST_USER_POSTCOPY_LISTEN]  = "VHOST_USER_POSTCOPY_LISTEN",
 };
 
+static int send_vhost_reply(int sockfd, struct VhostUserMsg *msg);
+static int read_vhost_message(int sockfd, struct VhostUserMsg *msg);
+
 static uint64_t
 get_blk_size(int fd)
 {
@@ -823,7 +826,7 @@ vhost_memory_changed(struct VhostUserMemory *new,
 
 static int
 vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
-                       int main_fd __rte_unused)
+                       int main_fd)
 {
        struct virtio_net *dev = *pdev;
        struct VhostUserMemory *memory = &msg->payload.memory;
@@ -967,11 +970,49 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
                        mmap_offset);
 
                if (dev->postcopy_listening) {
+                       /*
+                        * We haven't a better way right now than sharing
+                        * DPDK's virtual address with Qemu, so that Qemu can
+                        * retrieve the region offset when handling userfaults.
+                        */
+                       memory->regions[i].userspace_addr =
+                               reg->host_user_addr;
+               }
+       }
+       if (dev->postcopy_listening) {
+               /* Send the addresses back to qemu */
+               msg->fd_num = 0;
+               send_vhost_reply(main_fd, msg);
+
+               /* Wait for qemu to acknolwedge it's got the addresses
+                * we've got to wait before we're allowed to generate faults.
+                */
+               VhostUserMsg ack_msg;
+               if (read_vhost_message(main_fd, &ack_msg) <= 0) {
+                       RTE_LOG(ERR, VHOST_CONFIG,
+                               "Failed to read qemu ack on postcopy set-mem-table\n");
+                       goto err_mmap;
+               }
+               if (ack_msg.request.master != VHOST_USER_SET_MEM_TABLE) {
+                       RTE_LOG(ERR, VHOST_CONFIG,
+                               "Bad qemu ack on postcopy set-mem-table (%d)\n",
+                               ack_msg.request.master);
+                       goto err_mmap;
+               }
+
+               /* Now userfault register and we can use the memory */
+               for (i = 0; i < memory->nregions; i++) {
 #ifdef RTE_LIBRTE_VHOST_POSTCOPY
+                       reg = &dev->mem->regions[i];
                        struct uffdio_register reg_struct;
 
-                       reg_struct.range.start = (uint64_t)(uintptr_t)mmap_addr;
-                       reg_struct.range.len = mmap_size;
+                       /*
+                        * Let's register all the mmap'ed area to ensure
+                        * alignment on page boundary.
+                        */
+                       reg_struct.range.start =
+                               (uint64_t)(uintptr_t)reg->mmap_addr;
+                       reg_struct.range.len = reg->mmap_size;
                        reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
 
                        if (ioctl(dev->postcopy_ufd, UFFDIO_REGISTER,