On 19/02/2025 22:34, Maciej S. Szmigiero wrote:
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From: "Maciej S. Szmigiero" <maciej.szmigi...@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.szmigi...@oracle.com>
---
hw/vfio/migration-multifd.c | 103 ++++++++++++++++++++++++++++++++++++
hw/vfio/migration-multifd.h | 3 ++
hw/vfio/migration.c | 1 +
hw/vfio/trace-events | 1 +
4 files changed, 108 insertions(+)
diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c
index c2defc0efef0..5d5ee1393674 100644
--- a/hw/vfio/migration-multifd.c
+++ b/hw/vfio/migration-multifd.c
@@ -42,6 +42,11 @@ typedef struct VFIOStateBuffer {
} 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)
@@ -87,15 +92,113 @@ static VFIOStateBuffer
*vfio_state_buffers_at(VFIOStateBuffers *bufs, guint idx)
return &g_array_index(bufs->array, VFIOStateBuffer, idx);
}
+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, "state buffer %" PRIu32 " already filled",
+ packet->idx);
Let's add vbasedev->name to the error message so we know which device
caused the error.
+ 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_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;
+
+ /*
+ * 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());
To be clearer, I'd move the assert down to be just above
"QEMU_LOCK_GUARD(&multifd->load_bufs_mutex);".
+
+ if (!vfio_multifd_transfer_enabled(vbasedev)) {
+ error_setg(errp,
+ "got device state packet but not doing multifd transfer");
Let's add vbasedev->name to the error message so we know which device
caused the error.
+ return false;
+ }
+
+ assert(multifd);
+
+ if (data_size < sizeof(*packet)) {
+ error_setg(errp, "packet too short at %zu (min is %zu)",
+ data_size, sizeof(*packet));
Ditto.
+ return false;
+ }
+
+ if (packet->version != VFIO_DEVICE_STATE_PACKET_VER_CURRENT) {
+ error_setg(errp, "packet has unknown version %" PRIu32,
+ packet->version);
Ditto.
+ return false;
+ }
+
+ if (packet->idx == UINT32_MAX) {
+ error_setg(errp, "packet has too high idx");
Ditto.
+ return false;
+ }
+
+ trace_vfio_load_state_device_buffer_incoming(vbasedev->name, packet->idx);
+
+ 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;
+}
+
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);
Nit: move qemu_mutex_init() just above qemu_cond_init()?
Thanks.
+
+ multifd->load_buf_idx = 0;
+ multifd->load_buf_idx_last = UINT32_MAX;
+ qemu_cond_init(&multifd->load_bufs_buffer_ready_cond);
+
return multifd;
}
void vfio_multifd_free(VFIOMultifd *multifd)
{
+ 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-multifd.h b/hw/vfio/migration-multifd.h
index 1eefba3b2eed..d5ab7d6f85f5 100644
--- a/hw/vfio/migration-multifd.h
+++ b/hw/vfio/migration-multifd.h
@@ -22,4 +22,7 @@ bool vfio_multifd_transfer_enabled(VFIODevice *vbasedev);
bool vfio_multifd_transfer_setup(VFIODevice *vbasedev, Error **errp);
+bool vfio_load_state_buffer(void *opaque, char *data, size_t data_size,
+ Error **errp);
+
#endif
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 4311de763885..abaf4d08d4a9 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -806,6 +806,7 @@ static const SaveVMHandlers savevm_vfio_handlers = {
.load_setup = vfio_load_setup,
.load_cleanup = vfio_load_cleanup,
.load_state = vfio_load_state,
+ .load_state_buffer = vfio_load_state_buffer,
.switchover_ack_needed = vfio_switchover_ack_needed,
};
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 1bebe9877d88..042a3dc54a33 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -153,6 +153,7 @@ 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"
