On Mon, Jan 18, 2021 at 04:03:12PM +0000, Dr. David Alan Gilbert wrote:
* Stefano Garzarella (sgarz...@redhat.com) wrote:
Commit 9d7bd0826f introduced a new 'use-disabled-flag' property
set to true by default.
To allow the migration, we set this property to false in the hw_compat,
but in the wrong place (hw_compat_4_1).
Since commit 9d7bd0826f was released with QEMU 5.0, we move
'use-disabled-flag' property to hw_compat_4_2, so 4.2 machine types
will have the pre-patch behavior and the migration can work.
Be a little careful that fixing this probably causes a migration from
5.2->6.0 to fail with this machine type; so when we do these
type of fixes we often fix an old machine type between some pair of qemu
versions and then break it between a different set.
Good point!
I did some tests using the example below always using pc-q35-4.2 and it
seems that works well:
- 5.2 -> 6.0 pass
- 5.2 -> 4.2 FAIL
- 6.0 -> 5.2 pass
- 6.0 -> 4.2 pass
- 4.2 -> 5.2 pass
- 4.2 -> 6.0 pass
Should I run some more tests?
Thanks,
Stefano
Dave
The issue was discovered with vhost-vsock device and 4.2 machine
type without running any kernel in the VM:
$ qemu-4.2 -M pc-q35-4.2,accel=kvm \
-device vhost-vsock-pci,guest-cid=4 \
-monitor stdio -incoming tcp:0:3333
$ qemu-5.2 -M pc-q35-4.2,accel=kvm \
-device vhost-vsock-pci,guest-cid=3 \
-monitor stdio
(qemu) migrate -d tcp:0:3333
# qemu-4.2 output
qemu-system-x86_64: Failed to load virtio-vhost_vsock:virtio
qemu-system-x86_64: error while loading state for instance 0x0 of device
'0000:00:03.0/virtio-vhost_vsock'
qemu-system-x86_64: load of migration failed: No such file or directory
Reported-by: Jing Zhao <jinz...@redhat.com>
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1907255
Fixes: 9d7bd0826f ("virtio-pci: disable vring processing when bus-mastering is
disabled")
Cc: mdr...@linux.vnet.ibm.com
CC: qemu-sta...@nongnu.org
Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
---
hw/core/machine.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/core/machine.c b/hw/core/machine.c
index de3b8f1b31..5d6163ab70 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -70,12 +70,12 @@ GlobalProperty hw_compat_4_2[] = {
{ "qxl", "revision", "4" },
{ "qxl-vga", "revision", "4" },
{ "fw_cfg", "acpi-mr-restore", "false" },
+ { "virtio-device", "use-disabled-flag", "false" },
};
const size_t hw_compat_4_2_len = G_N_ELEMENTS(hw_compat_4_2);
GlobalProperty hw_compat_4_1[] = {
{ "virtio-pci", "x-pcie-flr-init", "off" },
- { "virtio-device", "use-disabled-flag", "false" },
};
const size_t hw_compat_4_1_len = G_N_ELEMENTS(hw_compat_4_1);
--
2.26.2
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
