Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally
on") added a check that returns an error if legacy support is on, but the
device is not legacy.
Unfortunately some devices were wrongly declared legacy even if they
were not (e.g vhost-vsock).
To avoid migration issues, we add a virtio-device property
(x-disable-legacy-check) to skip the legacy error, printing a warning
instaed, for machine types < 5.1.
Cc: qemu-sta...@nongnu.org
Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on")
Suggested-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
Suggested-by: Cornelia Huck <coh...@redhat.com>
Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
---
v3:
- added virtio_legacy_check_disabled() helper
- moved warning where error was returned [Cornelia]
v2:
- fixed Cornelia's e-mail address
---
include/hw/virtio/virtio.h | 2 ++
hw/core/machine.c | 1 +
hw/s390x/virtio-ccw.c | 15 ++++++++++++---
hw/virtio/virtio-pci.c | 14 ++++++++++++--
hw/virtio/virtio.c | 7 +++++++
5 files changed, 34 insertions(+), 5 deletions(-)
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 807280451b..f90cfb03e3 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -103,6 +103,7 @@ struct VirtIODevice
bool use_started;
bool started;
bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */
+ bool disable_legacy_check;
VMChangeStateEntry *vmstate;
char *bus_name;
uint8_t device_endian;
@@ -396,5 +397,6 @@ static inline bool virtio_device_disabled(VirtIODevice
*vdev)
}
bool virtio_legacy_allowed(VirtIODevice *vdev);
+bool virtio_legacy_check_disabled(VirtIODevice *vdev);
#endif
diff --git a/hw/core/machine.c b/hw/core/machine.c
index ea26d61237..b686eab798 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = {
{ "vmport", "x-signal-unsupported-cmd", "off" },
{ "vmport", "x-report-vmx-type", "off" },
{ "vmport", "x-cmds-v2", "off" },
+ { "virtio-device", "x-disable-legacy-check", "true" },
};
const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0);
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 8feb3451a0..97a01bc48a 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -1122,9 +1122,18 @@ static void virtio_ccw_device_plugged(DeviceState *d,
Error **errp)
}
if (!virtio_ccw_rev_max(dev) && !virtio_legacy_allowed(vdev)) {
- error_setg(errp, "Invalid value of property max_rev "
- "(is %d expected >= 1)", virtio_ccw_rev_max(dev));
- return;
+ /*
+ * To avoid migration issues, we allow legacy mode when legacy
+ * check is disabled in the old machine types (< 5.1).
+ */
+ if (virtio_legacy_check_disabled(vdev)) {
+ warn_report("device is modern-only, but for backward "
+ "compatibility legacy is allowed");
+ } else {
+ error_setg(errp, "Invalid value of property max_rev "
+ "(is %d expected >= 1)", virtio_ccw_rev_max(dev));
+ return;
+ }
}
if (virtio_get_num_queues(vdev) > VIRTIO_QUEUE_MAX) {
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 5bc769f685..bb91e34594 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1597,8 +1597,18 @@ static void virtio_pci_device_plugged(DeviceState *d,
Error **errp)
if (legacy) {
if (!virtio_legacy_allowed(vdev)) {
- error_setg(errp, "device is modern-only, use disable-legacy=on");
- return;
+ /*
+ * To avoid migration issues, we allow legacy mode when legacy
+ * check is disabled in the old machine types (< 5.1).
+ */
+ if (virtio_legacy_check_disabled(vdev)) {
+ warn_report("device is modern-only, but for backward "
+ "compatibility legacy is allowed");
+ } else {
+ error_setg(errp,
+ "device is modern-only, use disable-legacy=on");
+ return;
+ }
}
if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) {
error_setg(errp, "VIRTIO_F_IOMMU_PLATFORM was supported by"
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index e983025217..b85277da67 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -3304,6 +3304,11 @@ bool virtio_legacy_allowed(VirtIODevice *vdev)
}
}
+bool virtio_legacy_check_disabled(VirtIODevice *vdev)
+{
+ return vdev->disable_legacy_check;
+}
+
hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.desc;
@@ -3713,6 +3718,8 @@ static Property virtio_properties[] = {
DEFINE_VIRTIO_COMMON_FEATURES(VirtIODevice, host_features),
DEFINE_PROP_BOOL("use-started", VirtIODevice, use_started, true),
DEFINE_PROP_BOOL("use-disabled-flag", VirtIODevice, use_disabled_flag,
true),
+ DEFINE_PROP_BOOL("x-disable-legacy-check", VirtIODevice,
+ disable_legacy_check, false),
DEFINE_PROP_END_OF_LIST(),
};
--
2.26.2
