[RFC V1 3/7] vdpa/cpr: preserve device fd

[Steve Sistare <steven.sistare@oracle.com>]

Save the vdpa device fd in CPR state when it is created, and fetch the fd
from that state after CPR.  Remember that the fd was reused, for subsequent
patches.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 include/hw/virtio/vhost-vdpa.h |  3 +++
 net/vhost-vdpa.c               | 24 ++++++++++++++++++------
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
index 0a9575b469..427458cfed 100644
--- a/include/hw/virtio/vhost-vdpa.h
+++ b/include/hw/virtio/vhost-vdpa.h
@@ -54,6 +54,9 @@ typedef struct vhost_vdpa_shared {
     /* Vdpa must send shadow addresses as IOTLB key for data queues, not GPA */
     bool shadow_data;
 
+    /* Device descriptor is being reused after CPR restart */
+    bool reused;
+
     /* SVQ switching is in progress, or already completed? */
     SVQTransitionState svq_switching;
 } VhostVDPAShared;
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index daa38428c5..e6010e8900 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -12,6 +12,7 @@
 #include "qemu/osdep.h"
 #include "clients.h"
 #include "hw/virtio/virtio-net.h"
+#include "migration/cpr.h"
 #include "net/vhost_net.h"
 #include "net/vhost-vdpa.h"
 #include "hw/virtio/vhost-vdpa.h"
@@ -240,8 +241,10 @@ static void vhost_vdpa_cleanup(NetClientState *nc)
     if (s->vhost_vdpa.index != 0) {
         return;
     }
+    cpr_delete_fd(nc->name, 0);
     qemu_close(s->vhost_vdpa.shared->device_fd);
     g_free(s->vhost_vdpa.shared);
+    s->vhost_vdpa.shared = NULL;
 }
 
 /** Dummy SetSteeringEBPF to support RSS for vhost-vdpa backend  */
@@ -1675,6 +1678,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
                                        int nvqs,
                                        bool is_datapath,
                                        bool svq,
+                                       bool reused,
                                        struct vhost_vdpa_iova_range iova_range,
                                        uint64_t features,
                                        VhostVDPAShared *shared,
@@ -1712,6 +1716,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
                                           &s->vhost_vdpa.migration_blocker);
         s->vhost_vdpa.shared = g_new0(VhostVDPAShared, 1);
         s->vhost_vdpa.shared->device_fd = vdpa_device_fd;
+        s->vhost_vdpa.shared->reused = reused;
         s->vhost_vdpa.shared->iova_range = iova_range;
         s->vhost_vdpa.shared->shadow_data = svq;
     } else if (!is_datapath) {
@@ -1793,6 +1798,7 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
     struct vhost_vdpa_iova_range iova_range;
     NetClientState *nc;
     int queue_pairs, r, i = 0, has_cvq = 0;
+    bool reused;
 
     assert(netdev->type == NET_CLIENT_DRIVER_VHOST_VDPA);
     opts = &netdev->u.vhost_vdpa;
@@ -1808,13 +1814,17 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
         return -1;
     }
 
-    if (opts->vhostdev) {
+    vdpa_device_fd = cpr_find_fd(name, 0);
+    reused = (vdpa_device_fd != -1);
+
+    if (opts->vhostdev && vdpa_device_fd == -1) {
         vdpa_device_fd = qemu_open(opts->vhostdev, O_RDWR, errp);
         if (vdpa_device_fd == -1) {
             return -errno;
         }
-    } else {
-        /* has_vhostfd */
+        cpr_save_fd(name, 0, vdpa_device_fd);
+
+    } else if (opts->vhostfd) {
         vdpa_device_fd = monitor_fd_param(monitor_cur(), opts->vhostfd, errp);
         if (vdpa_device_fd == -1) {
             error_prepend(errp, "vhost-vdpa: unable to parse vhostfd: ");
@@ -1855,7 +1865,8 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
         }
         ncs[i] = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
                                      vdpa_device_fd, i, 2, true, opts->x_svq,
-                                     iova_range, features, shared, errp);
+                                     reused, iova_range, features, shared,
+                                     errp);
         if (!ncs[i])
             goto err;
     }
@@ -1866,8 +1877,8 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
 
         nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
                                  vdpa_device_fd, i, 1, false,
-                                 opts->x_svq, iova_range, features, shared,
-                                 errp);
+                                 opts->x_svq, reused, iova_range, features,
+                                 shared, errp);
         if (!nc)
             goto err;
     }
@@ -1882,6 +1893,7 @@ err:
     }
 
     qemu_close(vdpa_device_fd);
+    cpr_delete_fd(name, 0);
 
     return -1;
 }
-- 
2.39.3