From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
The multifd received data needs to be reassembled since device state
packets sent via different multifd channels can arrive out-of-order.
Therefore, each VFIO device state packet carries a header indicating its
position in the stream.
The raw device state data is saved into a VFIOStateBuffer for later
in-order loading into the device.
The last such VFIO device state packet should have
VFIO_DEVICE_STATE_CONFIG_STATE flag set and carry the device config state.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/e3bff515a8d61c582b94b409eb12a45b1a143a69.1741124640.git.maciej.szmigiero@oracle.com
[ clg: - Reordered savevm_vfio_handlers
- Added load_state_buffer documentation ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
docs/devel/migration/vfio.rst | 7 ++
hw/vfio/migration-multifd.h | 3 +
hw/vfio/migration-multifd.c | 163 ++++++++++++++++++++++++++++++++++
hw/vfio/migration.c | 4 +
hw/vfio/trace-events | 1 +
5 files changed, 178 insertions(+)
diff --git a/docs/devel/migration/vfio.rst b/docs/devel/migration/vfio.rst
index c49482eab66d8e831ea1c2c791fc895b51893e4d..8b1f28890a0ba708cc1e49d87b16e17a5d8f7c88 100644
--- a/docs/devel/migration/vfio.rst
+++ b/docs/devel/migration/vfio.rst
@@ -76,6 +76,10 @@ VFIO implements the device hooks for the iterative approach as follows:
* A ``load_state`` function that loads the config section and the data
sections that are generated by the save functions above.
+* A ``load_state_buffer`` function that loads the device state and the device
+ config that arrived via multifd channels.
+ It's used only in the multifd mode.
+
* ``cleanup`` functions for both save and load that perform any migration
related cleanup.
@@ -194,6 +198,9 @@ Live migration resume path
(RESTORE_VM, _ACTIVE, _STOP)
|
For each device, .load_state() is called for that device section data
+ transmitted via the main migration channel.
+ For data transmitted via multifd channels .load_state_buffer() is called
+ instead.
(RESTORE_VM, _ACTIVE, _RESUMING)
|
At the end, .load_cleanup() is called for each device and vCPUs are started
diff --git a/hw/vfio/migration-multifd.h b/hw/vfio/migration-multifd.h
index 2a7a76164f291d182172775524a5b11c0a560c58..8c6320fcb484ca9f779e14d4f9d814081d2f760e 100644
--- a/hw/vfio/migration-multifd.h
+++ b/hw/vfio/migration-multifd.h
@@ -20,4 +20,7 @@ void vfio_multifd_cleanup(VFIODevice *vbasedev);
bool vfio_multifd_transfer_supported(void);
bool vfio_multifd_transfer_enabled(VFIODevice *vbasedev);
+bool vfio_multifd_load_state_buffer(void *opaque, char *data, size_t data_size,
+ Error **errp);
+
#endif
diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c
index 091dc43210ad1459d5114da18336e73f6cb0baf9..79df11b7baa991763039b395c34931e796e711b0 100644
--- a/hw/vfio/migration-multifd.c
+++ b/hw/vfio/migration-multifd.c
@@ -32,18 +32,181 @@ typedef struct VFIODeviceStatePacket {
uint8_t data[0];
} QEMU_PACKED VFIODeviceStatePacket;
+/* type safety */
+typedef struct VFIOStateBuffers {
+ GArray *array;
+} VFIOStateBuffers;
+
+typedef struct VFIOStateBuffer {
+ bool is_present;
+ char *data;
+ size_t len;
+} VFIOStateBuffer;
+
typedef struct VFIOMultifd {
+ VFIOStateBuffers load_bufs;
+ QemuCond load_bufs_buffer_ready_cond;
+ QemuMutex load_bufs_mutex; /* Lock order: this lock -> BQL */
+ uint32_t load_buf_idx;
+ uint32_t load_buf_idx_last;
} VFIOMultifd;
+static void vfio_state_buffer_clear(gpointer data)
+{
+ VFIOStateBuffer *lb = data;
+
+ if (!lb->is_present) {
+ return;
+ }
+
+ g_clear_pointer(&lb->data, g_free);
+ lb->is_present = false;
+}
+
+static void vfio_state_buffers_init(VFIOStateBuffers *bufs)
+{
+ bufs->array = g_array_new(FALSE, TRUE, sizeof(VFIOStateBuffer));
+ g_array_set_clear_func(bufs->array, vfio_state_buffer_clear);
+}
+
+static void vfio_state_buffers_destroy(VFIOStateBuffers *bufs)
+{
+ g_clear_pointer(&bufs->array, g_array_unref);
+}
+
+static void vfio_state_buffers_assert_init(VFIOStateBuffers *bufs)
+{
+ assert(bufs->array);
+}
+
+static unsigned int vfio_state_buffers_size_get(VFIOStateBuffers *bufs)
+{
+ return bufs->array->len;
+}
+
+static void vfio_state_buffers_size_set(VFIOStateBuffers *bufs,
+ unsigned int size)
+{
+ g_array_set_size(bufs->array, size);
+}
+
+static VFIOStateBuffer *vfio_state_buffers_at(VFIOStateBuffers *bufs,
+ unsigned int idx)
+{
+ return &g_array_index(bufs->array, VFIOStateBuffer, idx);
+}
+
+/* called with load_bufs_mutex locked */
+static bool vfio_load_state_buffer_insert(VFIODevice *vbasedev,
+ VFIODeviceStatePacket *packet,
+ size_t packet_total_size,
+ Error **errp)
+{
+ VFIOMigration *migration = vbasedev->migration;
+ VFIOMultifd *multifd = migration->multifd;
+ VFIOStateBuffer *lb;
+
+ vfio_state_buffers_assert_init(&multifd->load_bufs);
+ if (packet->idx >= vfio_state_buffers_size_get(&multifd->load_bufs)) {
+ vfio_state_buffers_size_set(&multifd->load_bufs, packet->idx + 1);
+ }
+
+ lb = vfio_state_buffers_at(&multifd->load_bufs, packet->idx);
+ if (lb->is_present) {
+ error_setg(errp, "%s: state buffer %" PRIu32 " already filled",
+ vbasedev->name, packet->idx);
+ return false;
+ }
+
+ assert(packet->idx >= multifd->load_buf_idx);
+
+ lb->data = g_memdup2(&packet->data, packet_total_size - sizeof(*packet));
+ lb->len = packet_total_size - sizeof(*packet);
+ lb->is_present = true;
+
+ return true;
+}
+
+bool vfio_multifd_load_state_buffer(void *opaque, char *data, size_t data_size,
+ Error **errp)
+{
+ VFIODevice *vbasedev = opaque;
+ VFIOMigration *migration = vbasedev->migration;
+ VFIOMultifd *multifd = migration->multifd;
+ VFIODeviceStatePacket *packet = (VFIODeviceStatePacket *)data;
+
+ if (!vfio_multifd_transfer_enabled(vbasedev)) {
+ error_setg(errp,
+ "%s: got device state packet but not doing multifd transfer",
+ vbasedev->name);
+ return false;
+ }
+
+ assert(multifd);
+
+ if (data_size < sizeof(*packet)) {
+ error_setg(errp, "%s: packet too short at %zu (min is %zu)",
+ vbasedev->name, data_size, sizeof(*packet));
+ return false;
+ }
+
+ if (packet->version != VFIO_DEVICE_STATE_PACKET_VER_CURRENT) {
+ error_setg(errp, "%s: packet has unknown version %" PRIu32,
+ vbasedev->name, packet->version);
+ return false;
+ }
+
+ if (packet->idx == UINT32_MAX) {
+ error_setg(errp, "%s: packet index is invalid", vbasedev->name);
+ return false;
+ }
+
+ trace_vfio_load_state_device_buffer_incoming(vbasedev->name, packet->idx);
+
+ /*
+ * Holding BQL here would violate the lock order and can cause
+ * a deadlock once we attempt to lock load_bufs_mutex below.
+ */
+ assert(!bql_locked());
+
+ WITH_QEMU_LOCK_GUARD(&multifd->load_bufs_mutex) {
+ /* config state packet should be the last one in the stream */
+ if (packet->flags & VFIO_DEVICE_STATE_CONFIG_STATE) {
+ multifd->load_buf_idx_last = packet->idx;
+ }
+
+ if (!vfio_load_state_buffer_insert(vbasedev, packet, data_size,
+ errp)) {
+ return false;
+ }
+
+ qemu_cond_signal(&multifd->load_bufs_buffer_ready_cond);
+ }
+
+ return true;
+}
+
static VFIOMultifd *vfio_multifd_new(void)
{
VFIOMultifd *multifd = g_new(VFIOMultifd, 1);
+ vfio_state_buffers_init(&multifd->load_bufs);
+
+ qemu_mutex_init(&multifd->load_bufs_mutex);
+
+ multifd->load_buf_idx = 0;
+ multifd->load_buf_idx_last = UINT32_MAX;
+ qemu_cond_init(&multifd->load_bufs_buffer_ready_cond);
+
return multifd;
}
static void vfio_multifd_free(VFIOMultifd *multifd)
{
+ vfio_state_buffers_destroy(&multifd->load_bufs);
+ qemu_cond_destroy(&multifd->load_bufs_buffer_ready_cond);
+ qemu_mutex_destroy(&multifd->load_bufs_mutex);
+
g_free(multifd);
}
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 3c8286ae62300122582ae5ced26f5cbf5742818a..2cdb92356e0a2afb64109c10536c857b19f7e7c5 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -802,6 +802,10 @@ static const SaveVMHandlers savevm_vfio_handlers = {
.load_cleanup = vfio_load_cleanup,
.load_state = vfio_load_state,
.switchover_ack_needed = vfio_switchover_ack_needed,
+ /*
+ * Multifd support
+ */
+ .load_state_buffer = vfio_multifd_load_state_buffer,
};
/* ---------------------------------------------------------------------- */
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index a02c668f28a43f73ed2db9f15827f26fed0994c3..404ea079b25c49fe25f4c9b05f0cde4f0536fdd7 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -154,6 +154,7 @@ vfio_load_device_config_state_start(const char *name) " (%s)"
vfio_load_device_config_state_end(const char *name) " (%s)"
vfio_load_state(const char *name, uint64_t data) " (%s) data 0x%"PRIx64
vfio_load_state_device_data(const char *name, uint64_t data_size, int ret) " (%s) size %"PRIu64" ret %d"
+vfio_load_state_device_buffer_incoming(const char *name, uint32_t idx) " (%s) idx %"PRIu32
vfio_migration_realize(const char *name) " (%s)"
vfio_migration_set_device_state(const char *name, const char *state) " (%s) state %s"
vfio_migration_set_state(const char *name, const char *new_state, const char *recover_state) " (%s) new state %s, recover state %s"
--
2.48.1