* [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
@ 2021-01-08 17:12 Stefano Garzarella
2021-01-18 9:19 ` Stefano Garzarella
2021-01-18 16:03 ` Dr. David Alan Gilbert
0 siblings, 2 replies; 8+ messages in thread
From: Stefano Garzarella @ 2021-01-08 17:12 UTC (permalink / raw)
To: qemu-devel
Cc: Eduardo Habkost, Juan Quintela, qemu-stable, Michael S. Tsirkin,
mdroth, Dr . David Alan Gilbert, Jing Zhao
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>
---
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
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
2021-01-08 17:12 [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2 Stefano Garzarella
@ 2021-01-18 9:19 ` Stefano Garzarella
2021-01-18 11:51 ` Michael S. Tsirkin
2021-01-18 16:03 ` Dr. David Alan Gilbert
1 sibling, 1 reply; 8+ messages in thread
From: Stefano Garzarella @ 2021-01-18 9:19 UTC (permalink / raw)
To: qemu-devel, Michael S. Tsirkin
Cc: Eduardo Habkost, Juan Quintela, qemu-stable,
Dr . David Alan Gilbert, Jing Zhao
Ping :-)
On Fri, Jan 08, 2021 at 06:12:52PM +0100, Stefano Garzarella 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.
>
>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>
>---
> 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
>
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
2021-01-18 9:19 ` Stefano Garzarella
@ 2021-01-18 11:51 ` Michael S. Tsirkin
0 siblings, 0 replies; 8+ messages in thread
From: Michael S. Tsirkin @ 2021-01-18 11:51 UTC (permalink / raw)
To: Stefano Garzarella
Cc: Eduardo Habkost, Juan Quintela, qemu-stable, qemu-devel,
Jing Zhao, Dr . David Alan Gilbert
queued, thanks!
On Mon, Jan 18, 2021 at 10:19:55AM +0100, Stefano Garzarella wrote:
> Ping :-)
>
> On Fri, Jan 08, 2021 at 06:12:52PM +0100, Stefano Garzarella 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.
> >
> > 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>
> > ---
> > 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
> >
> >
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
2021-01-08 17:12 [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2 Stefano Garzarella
2021-01-18 9:19 ` Stefano Garzarella
@ 2021-01-18 16:03 ` Dr. David Alan Gilbert
2021-01-19 8:45 ` Stefano Garzarella
1 sibling, 1 reply; 8+ messages in thread
From: Dr. David Alan Gilbert @ 2021-01-18 16:03 UTC (permalink / raw)
To: Stefano Garzarella
Cc: Eduardo Habkost, Juan Quintela, qemu-stable, Michael S. Tsirkin,
mdroth, qemu-devel, Jing Zhao
* Stefano Garzarella (sgarzare@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.
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 <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>
> ---
> 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 / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
2021-01-18 16:03 ` Dr. David Alan Gilbert
@ 2021-01-19 8:45 ` Stefano Garzarella
2021-01-26 14:17 ` Michael S. Tsirkin
2021-01-27 14:28 ` Dr. David Alan Gilbert
0 siblings, 2 replies; 8+ messages in thread
From: Stefano Garzarella @ 2021-01-19 8:45 UTC (permalink / raw)
To: Dr. David Alan Gilbert
Cc: Eduardo Habkost, Juan Quintela, qemu-stable, Michael S. Tsirkin,
mdroth, qemu-devel, Jing Zhao
On Mon, Jan 18, 2021 at 04:03:12PM +0000, Dr. David Alan Gilbert wrote:
>* Stefano Garzarella (sgarzare@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 <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>
>> ---
>> 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 / dgilbert@redhat.com / Manchester, UK
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
2021-01-19 8:45 ` Stefano Garzarella
@ 2021-01-26 14:17 ` Michael S. Tsirkin
2021-01-27 14:28 ` Dr. David Alan Gilbert
1 sibling, 0 replies; 8+ messages in thread
From: Michael S. Tsirkin @ 2021-01-26 14:17 UTC (permalink / raw)
To: Stefano Garzarella
Cc: Eduardo Habkost, Juan Quintela, qemu-devel, qemu-stable, mdroth,
Dr. David Alan Gilbert, Jing Zhao
On Tue, Jan 19, 2021 at 09:45:19AM +0100, Stefano Garzarella wrote:
> On Mon, Jan 18, 2021 at 04:03:12PM +0000, Dr. David Alan Gilbert wrote:
> > * Stefano Garzarella (sgarzare@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
dgilbert how about an ack?
> >
> > 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 <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>
> > > ---
> > > 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 / dgilbert@redhat.com / Manchester, UK
> >
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
2021-01-19 8:45 ` Stefano Garzarella
2021-01-26 14:17 ` Michael S. Tsirkin
@ 2021-01-27 14:28 ` Dr. David Alan Gilbert
2021-01-27 14:34 ` Stefano Garzarella
1 sibling, 1 reply; 8+ messages in thread
From: Dr. David Alan Gilbert @ 2021-01-27 14:28 UTC (permalink / raw)
To: Stefano Garzarella
Cc: Eduardo Habkost, Juan Quintela, qemu-stable, Michael S. Tsirkin,
mdroth, qemu-devel, Jing Zhao
* Stefano Garzarella (sgarzare@redhat.com) wrote:
> On Mon, Jan 18, 2021 at 04:03:12PM +0000, Dr. David Alan Gilbert wrote:
> > * Stefano Garzarella (sgarzare@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?
Apologies for the delay; I had to step back and understand a bit about
what was going on.
The problem here is that you're sending a 'disabled' subsection when
that option is true; your patch doesn't change the 4.1 machine type but
it does change the 4.2 machine type; and that makes the 4.2 machine type
not send it; so that means your patched version *will* work to existing
code (because it's a subsection anyway it doesn't break the stream
format when it's missing).
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 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 <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>
> > > ---
> > > 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 / dgilbert@redhat.com / Manchester, UK
> >
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2
2021-01-27 14:28 ` Dr. David Alan Gilbert
@ 2021-01-27 14:34 ` Stefano Garzarella
0 siblings, 0 replies; 8+ messages in thread
From: Stefano Garzarella @ 2021-01-27 14:34 UTC (permalink / raw)
To: Dr. David Alan Gilbert
Cc: Eduardo Habkost, Juan Quintela, qemu-stable, Michael S. Tsirkin,
mdroth, qemu-devel, Jing Zhao
On Wed, Jan 27, 2021 at 02:28:13PM +0000, Dr. David Alan Gilbert wrote:
>* Stefano Garzarella (sgarzare@redhat.com) wrote:
>> On Mon, Jan 18, 2021 at 04:03:12PM +0000, Dr. David Alan Gilbert wrote:
>> > * Stefano Garzarella (sgarzare@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?
>
>Apologies for the delay; I had to step back and understand a bit about
>what was going on.
no problem :-)
>
>The problem here is that you're sending a 'disabled' subsection when
>that option is true; your patch doesn't change the 4.1 machine type but
>it does change the 4.2 machine type; and that makes the 4.2 machine type
>not send it; so that means your patched version *will* work to existing
>code (because it's a subsection anyway it doesn't break the stream
>format when it's missing).
>
Thanks for the detailed explanation!
>
>Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
Thanks,
Stefano
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2021-01-27 14:36 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-08 17:12 [PATCH] virtio: move 'use-disabled-flag' property to hw_compat_4_2 Stefano Garzarella
2021-01-18 9:19 ` Stefano Garzarella
2021-01-18 11:51 ` Michael S. Tsirkin
2021-01-18 16:03 ` Dr. David Alan Gilbert
2021-01-19 8:45 ` Stefano Garzarella
2021-01-26 14:17 ` Michael S. Tsirkin
2021-01-27 14:28 ` Dr. David Alan Gilbert
2021-01-27 14:34 ` Stefano Garzarella
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