From: Hanna Czenczek <hreitz@redhat.com>
To: qemu-devel@nongnu.org, virtio-fs@redhat.com
Cc: "Hanna Czenczek" <hreitz@redhat.com>,
"Michael S . Tsirkin" <mst@redhat.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"German Maglione" <gmaglione@redhat.com>,
"Eugenio Pérez" <eperezma@redhat.com>,
"Anton Kuchin" <antonkuchin@yandex-team.ru>
Subject: [Virtio-fs] [PATCH v5 7/7] vhost-user-fs: Implement internal migration
Date: Mon, 16 Oct 2023 15:42:43 +0200 [thread overview]
Message-ID: <20231016134243.68248-8-hreitz@redhat.com> (raw)
In-Reply-To: <20231016134243.68248-1-hreitz@redhat.com>
A virtio-fs device's VM state consists of:
- the virtio device (vring) state (VMSTATE_VIRTIO_DEVICE)
- the back-end's (virtiofsd's) internal state
We get/set the latter via the new vhost operations to transfer migratory
state. It is its own dedicated subsection, so that for external
migration, it can be disabled.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
---
hw/virtio/vhost-user-fs.c | 101 +++++++++++++++++++++++++++++++++++++-
1 file changed, 100 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
index 49d699ffc2..eb91723855 100644
--- a/hw/virtio/vhost-user-fs.c
+++ b/hw/virtio/vhost-user-fs.c
@@ -298,9 +298,108 @@ static struct vhost_dev *vuf_get_vhost(VirtIODevice *vdev)
return &fs->vhost_dev;
}
+/**
+ * Fetch the internal state from virtiofsd and save it to `f`.
+ */
+static int vuf_save_state(QEMUFile *f, void *pv, size_t size,
+ const VMStateField *field, JSONWriter *vmdesc)
+{
+ VirtIODevice *vdev = pv;
+ VHostUserFS *fs = VHOST_USER_FS(vdev);
+ Error *local_error = NULL;
+ int ret;
+
+ ret = vhost_save_backend_state(&fs->vhost_dev, f, &local_error);
+ if (ret < 0) {
+ error_reportf_err(local_error,
+ "Error saving back-end state of %s device %s "
+ "(tag: \"%s\"): ",
+ vdev->name, vdev->parent_obj.canonical_path,
+ fs->conf.tag ?: "<none>");
+ return ret;
+ }
+
+ return 0;
+}
+
+/**
+ * Load virtiofsd's internal state from `f` and send it over to virtiofsd.
+ */
+static int vuf_load_state(QEMUFile *f, void *pv, size_t size,
+ const VMStateField *field)
+{
+ VirtIODevice *vdev = pv;
+ VHostUserFS *fs = VHOST_USER_FS(vdev);
+ Error *local_error = NULL;
+ int ret;
+
+ ret = vhost_load_backend_state(&fs->vhost_dev, f, &local_error);
+ if (ret < 0) {
+ error_reportf_err(local_error,
+ "Error loading back-end state of %s device %s "
+ "(tag: \"%s\"): ",
+ vdev->name, vdev->parent_obj.canonical_path,
+ fs->conf.tag ?: "<none>");
+ return ret;
+ }
+
+ return 0;
+}
+
+static bool vuf_is_internal_migration(void *opaque)
+{
+ /* TODO: Return false when an external migration is requested */
+ return true;
+}
+
+static int vuf_check_migration_support(void *opaque)
+{
+ VirtIODevice *vdev = opaque;
+ VHostUserFS *fs = VHOST_USER_FS(vdev);
+
+ if (!vhost_supports_device_state(&fs->vhost_dev)) {
+ error_report("Back-end of %s device %s (tag: \"%s\") does not support "
+ "migration through qemu",
+ vdev->name, vdev->parent_obj.canonical_path,
+ fs->conf.tag ?: "<none>");
+ return -ENOTSUP;
+ }
+
+ return 0;
+}
+
+static const VMStateDescription vuf_backend_vmstate;
+
static const VMStateDescription vuf_vmstate = {
.name = "vhost-user-fs",
- .unmigratable = 1,
+ .version_id = 0,
+ .fields = (VMStateField[]) {
+ VMSTATE_VIRTIO_DEVICE,
+ VMSTATE_END_OF_LIST()
+ },
+ .subsections = (const VMStateDescription * []) {
+ &vuf_backend_vmstate,
+ NULL,
+ }
+};
+
+static const VMStateDescription vuf_backend_vmstate = {
+ .name = "vhost-user-fs-backend",
+ .version_id = 0,
+ .needed = vuf_is_internal_migration,
+ .pre_load = vuf_check_migration_support,
+ .pre_save = vuf_check_migration_support,
+ .fields = (VMStateField[]) {
+ {
+ .name = "back-end",
+ .info = &(const VMStateInfo) {
+ .name = "virtio-fs back-end state",
+ .get = vuf_load_state,
+ .put = vuf_save_state,
+ },
+ },
+ VMSTATE_END_OF_LIST()
+ },
};
static Property vuf_properties[] = {
--
2.41.0
prev parent reply other threads:[~2023-10-16 13:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-16 13:42 [Virtio-fs] [PATCH v5 0/7] vhost-user: Back-end state migration Hanna Czenczek
2023-10-16 13:42 ` [Virtio-fs] [PATCH v5 1/7] vhost-user.rst: Improve [GS]ET_VRING_BASE doc Hanna Czenczek
2023-10-16 13:42 ` [Virtio-fs] [PATCH v5 2/7] vhost-user.rst: Clarify enabling/disabling vrings Hanna Czenczek
2023-10-16 13:42 ` [Virtio-fs] [PATCH v5 3/7] vhost-user.rst: Introduce suspended state Hanna Czenczek
2023-10-16 13:42 ` [Virtio-fs] [PATCH v5 4/7] vhost-user.rst: Migrating back-end-internal state Hanna Czenczek
2023-10-16 13:42 ` [Virtio-fs] [PATCH v5 5/7] vhost-user: Interface for migration state transfer Hanna Czenczek
2023-10-16 13:42 ` [Virtio-fs] [PATCH v5 6/7] vhost: Add high-level state save/load functions Hanna Czenczek
2023-10-16 13:42 ` Hanna Czenczek [this message]
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