[Qemu-devel] [PATCH v5 08/21] vhost-user: send log shm fd along with log_base

[marcandre.lureau@redhat.com]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Send the shm for the dirty pages logging if the backend supports
VHOST_USER_PROTOCOL_F_LOG_SHMFD. Wait for a reply to make sure
the old log is no longer used.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 hw/virtio/vhost-backend.c         |  3 ++-
 hw/virtio/vhost-user.c            | 32 ++++++++++++++++++++++++++++----
 hw/virtio/vhost.c                 |  5 +++--
 include/hw/virtio/vhost-backend.h |  4 +++-
 4 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 88d33fd..87ab028 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -50,7 +50,8 @@ static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
     return idx - dev->vq_index;
 }
 
-static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base)
+static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base,
+                              struct vhost_log *log)
 {
     return vhost_kernel_call(dev, VHOST_SET_LOG_BASE, &base);
 }
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index fd4fcbf..6420efd 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -25,9 +25,10 @@
 
 #define VHOST_MEMORY_MAX_NREGIONS    8
 #define VHOST_USER_F_PROTOCOL_FEATURES 30
-#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x1ULL
 
-#define VHOST_USER_PROTOCOL_F_MQ    0
+#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x3ULL
+#define VHOST_USER_PROTOCOL_F_MQ         0
+#define VHOST_USER_PROTOCOL_F_LOG_SHMFD  1
 
 typedef enum VhostUserRequest {
     VHOST_USER_NONE = 0,
@@ -366,8 +367,13 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
     return 0;
 }
 
-static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base)
+static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base,
+                              struct vhost_log *log)
 {
+    int fds[VHOST_MEMORY_MAX_NREGIONS];
+    size_t fd_num = 0;
+    bool shmfd = virtio_has_feature(dev->protocol_features,
+                                    VHOST_USER_PROTOCOL_F_LOG_SHMFD);
     VhostUserMsg msg = {
         .request = VHOST_USER_SET_LOG_BASE,
         .flags = VHOST_USER_VERSION,
@@ -375,7 +381,25 @@ static int vhost_set_log_base(struct vhost_dev *dev, uint64_t base)
         .size = sizeof(m.u64),
     };
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (shmfd && log->fd != -1) {
+        fds[fd_num++] = log->fd;
+    }
+
+    vhost_user_write(dev, &msg, fds, fd_num);
+
+    if (shmfd) {
+        msg.size = 0;
+        if (vhost_user_read(dev, &msg) < 0) {
+            return 0;
+        }
+
+        if (msg.request != VHOST_USER_SET_LOG_BASE) {
+            error_report("Received unexpected msg type. "
+                         "Expected %d received %d",
+                         VHOST_USER_SET_LOG_BASE, msg.request);
+            return -1;
+        }
+    }
 
     return 0;
 }
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 7f01cd6..9b73f83 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -366,7 +366,7 @@ static inline void vhost_dev_log_resize(struct vhost_dev* dev, uint64_t size)
 
     /* inform backend of log switching, this must be done before
        releasing the current log, to ensure no logging is lost */
-    r = dev->vhost_ops->vhost_set_log_base(dev, log_base);
+    r = dev->vhost_ops->vhost_set_log_base(dev, log_base, log);
     assert(r >= 0);
     vhost_log_put(dev, true);
     dev->log = log;
@@ -1172,7 +1172,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
         hdev->log = vhost_log_get(hdev->log_size, share);
         log_base = (uintptr_t)hdev->log->log;
         r = hdev->vhost_ops->vhost_set_log_base(hdev,
-                                                hdev->log_size ? log_base : 0);
+                                                hdev->log_size ? log_base : 0,
+                                                hdev->log);
         if (r < 0) {
             r = -errno;
             goto fail_log;
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index c6b688a..485279b 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -19,6 +19,7 @@ typedef enum VhostBackendType {
 } VhostBackendType;
 
 struct vhost_dev;
+struct vhost_log;
 
 typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int request,
              void *arg);
@@ -27,7 +28,8 @@ typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
 typedef int (*vhost_backend_get_vq_index)(struct vhost_dev *dev, int idx);
 typedef int (*vhost_backend_set_vring_enable)(struct vhost_dev *dev, int enable);
 
-typedef int (*vhost_set_log_base_op)(struct vhost_dev *dev, uint64_t base);
+typedef int (*vhost_set_log_base_op)(struct vhost_dev *dev, uint64_t base,
+                                     struct vhost_log *log);
 
 typedef struct VhostOps {
     VhostBackendType backend_type;
-- 
2.4.3