On 06/03/2025 12:32, Cédric Le Goater wrote:
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On 3/6/25 11:15, Maciej S. Szmigiero wrote:
On 6.03.2025 07:47, Avihai Horon wrote:
On 05/03/2025 0:03, Maciej S. Szmigiero wrote:
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From: "Maciej S. Szmigiero" <maciej.szmigi...@oracle.com>
Implement the multifd device state transfer via additional per-device
thread inside save_live_complete_precopy_thread handler.
Switch between doing the data transfer in the new handler and doing it
in the old save_state handler depending if VFIO multifd transfer is
enabled
or not.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigi...@oracle.com>
---
hw/vfio/migration-multifd.c | 142
++++++++++++++++++++++++++++++++++
hw/vfio/migration-multifd.h | 6 ++
hw/vfio/migration.c | 22 ++++--
hw/vfio/trace-events | 2 +
include/hw/vfio/vfio-common.h | 6 ++
5 files changed, 172 insertions(+), 6 deletions(-)
diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c
index 1d81233c755f..bfb9a72fa450 100644
--- a/hw/vfio/migration-multifd.c
+++ b/hw/vfio/migration-multifd.c
@@ -496,6 +496,148 @@ bool vfio_multifd_setup(VFIODevice *vbasedev,
bool alloc_multifd, Error **errp)
return true;
}
+void vfio_multifd_emit_dummy_eos(VFIODevice *vbasedev, QEMUFile *f)
+{
+ assert(vfio_multifd_transfer_enabled(vbasedev));
+
+ /*
+ * Emit dummy NOP data on the main migration channel since the
actual
+ * device state transfer is done via multifd channels.
+ */
+ qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+}
+
+static bool
+vfio_save_complete_precopy_thread_config_state(VFIODevice *vbasedev,
+ char *idstr,
+ uint32_t instance_id,
+ uint32_t idx,
+ Error **errp)
+{
+ g_autoptr(QIOChannelBuffer) bioc = NULL;
+ g_autoptr(QEMUFile) f = NULL;
+ int ret;
+ g_autofree VFIODeviceStatePacket *packet = NULL;
+ size_t packet_len;
+
+ bioc = qio_channel_buffer_new(0);
+ qio_channel_set_name(QIO_CHANNEL(bioc),
"vfio-device-config-save");
+
+ f = qemu_file_new_output(QIO_CHANNEL(bioc));
+
+ if (vfio_save_device_config_state(f, vbasedev, errp)) {
+ return false;
+ }
+
+ ret = qemu_fflush(f);
+ if (ret) {
+ error_setg(errp, "%s: save config state flush failed: %d",
+ vbasedev->name, ret);
+ return false;
+ }
+
+ packet_len = sizeof(*packet) + bioc->usage;
+ packet = g_malloc0(packet_len);
+ packet->version = VFIO_DEVICE_STATE_PACKET_VER_CURRENT;
+ packet->idx = idx;
+ packet->flags = VFIO_DEVICE_STATE_CONFIG_STATE;
The packet is sent on the wire.
Shouldn't we use cpu_to_be32() for version, idx and flags? Also
below in vfio_multifd_save_complete_precopy_thread().
And then use be32_to_cpu() in patch #26 when receiving the packet?
Is it even possible to migrate to a host with different endianess here?
Also AFAIK big endian hosts barely exist today, is any of them even
VFIO-capable?
s390x is VFIO capable. VFIO PCI migration is not supported on these.
It is indeed a niche use case and not even applicable today, but if we
want to add support for it after the release, we will have to add a
compatibility option for older QEMUs.
If we add support for it now, then we can avoid the compatibility option.
It's a really small change and it can come even after the series is
merged, as a fix.
So IMHO it wouldn't hurt, for completeness.
Thanks.
