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virtio: move 'use-disabled-flag' property to hw_compat_4_2

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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.

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 <jinzhao@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: mdroth@linux.vnet.ibm.com
CC: qemu-stable@nongnu.org
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20210108171252.209502-1-sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefano Garzarella 2021-01-08 18:12:52 +01:00 committed by Michael S. Tsirkin
parent 08b1df8ff4
commit c126b4c57e
1 changed files with 1 additions and 1 deletions
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2
hw/core/machine.c
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@ -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);