* [Qemu-devel] [PATCH for-2.5] virtio: handle non-virtio-1-capable backend
@ 2015-12-02 14:09 Cornelia Huck
2015-12-02 16:43 ` Michael S. Tsirkin
0 siblings, 1 reply; 4+ messages in thread
From: Cornelia Huck @ 2015-12-02 14:09 UTC (permalink / raw)
To: mst; +Cc: Cornelia Huck, borntraeger, jasowang, qemu-devel
If you run a qemu advertising VERSION_1 with an old kernel where
vhost did not yet support VERSION_1, you'll end up with a device
that is {modern pci|ccw revision 1} but does not advertise VERSION_1.
This is not a sensible configuration and is rejected by the Linux
guest drivers.
To fix this, add a ->post_plugged() callback invoked after features
have been queried that can handle the VERSION_1 bit being withdrawn
and change pci (only setup modern if VERSION_1 is still present) and
ccw (fall back to revision 0 if VERSION_1 is gone).
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
Michael: I think this should go into 2.5, as otherwise ccw (which
defaults to virtio-1 with 2.5) will be broken with old host kernels.
I need someone to give virtio-pci some testing, as I do not have
a proper setup for that. ccw is working fine.
Changes from initial writeup:
- Move pci-modern init to post_plugged instead of undoing [Jason]
- Add a proper patch description + signoff
- Add some comments
---
hw/s390x/virtio-ccw.c | 12 ++++++
hw/virtio/virtio-bus.c | 3 ++
hw/virtio/virtio-pci.c | 96 ++++++++++++++++++++++++++----------------
include/hw/virtio/virtio-bus.h | 5 +++
4 files changed, 80 insertions(+), 36 deletions(-)
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index fb103b7..63da303 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -1555,6 +1555,17 @@ static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
d->hotplugged, 1);
}
+static void virtio_ccw_post_plugged(DeviceState *d, Error **errp)
+{
+ VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
+ VirtIODevice *vdev = virtio_bus_get_device(&dev->bus);
+
+ if (!virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+ /* A backend didn't support modern virtio. */
+ dev->max_rev = 0;
+ }
+}
+
static void virtio_ccw_device_unplugged(DeviceState *d)
{
VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
@@ -1891,6 +1902,7 @@ static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data)
k->save_config = virtio_ccw_save_config;
k->load_config = virtio_ccw_load_config;
k->device_plugged = virtio_ccw_device_plugged;
+ k->post_plugged = virtio_ccw_post_plugged;
k->device_unplugged = virtio_ccw_device_unplugged;
}
diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index febda76..81c7cdd 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -56,6 +56,9 @@ void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
assert(vdc->get_features != NULL);
vdev->host_features = vdc->get_features(vdev, vdev->host_features,
errp);
+ if (klass->post_plugged != NULL) {
+ klass->post_plugged(qbus->parent, errp);
+ }
}
/* Reset the virtio_bus */
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index dd48562..af59496 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1626,7 +1626,6 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
VirtioBusState *bus = &proxy->bus;
bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
- bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY;
uint8_t *config;
uint32_t size;
VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
@@ -1653,6 +1652,65 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
if (modern) {
+ virtio_add_feature(&vdev->host_features, VIRTIO_F_VERSION_1);
+ /* Let's see if this feature bit sticks before doing further init. */
+ }
+
+ if (proxy->nvectors) {
+ int err = msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors,
+ proxy->msix_bar);
+ if (err) {
+ /* Notice when a system that supports MSIx can't initialize it. */
+ if (err != -ENOTSUP) {
+ error_report("unable to init msix vectors to %" PRIu32,
+ proxy->nvectors);
+ }
+ proxy->nvectors = 0;
+ }
+ }
+
+ proxy->pci_dev.config_write = virtio_write_config;
+ proxy->pci_dev.config_read = virtio_read_config;
+
+ if (legacy) {
+ size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev)
+ + virtio_bus_get_vdev_config_len(bus);
+ size = pow2ceil(size);
+
+ memory_region_init_io(&proxy->bar, OBJECT(proxy),
+ &virtio_pci_config_ops,
+ proxy, "virtio-pci", size);
+
+ pci_register_bar(&proxy->pci_dev, proxy->legacy_io_bar,
+ PCI_BASE_ADDRESS_SPACE_IO, &proxy->bar);
+ }
+
+ if (!kvm_has_many_ioeventfds()) {
+ proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
+ }
+
+ virtio_add_feature(&vdev->host_features, VIRTIO_F_BAD_FEATURE);
+}
+
+static void virtio_pci_post_plugged(DeviceState *d, Error **errp)
+{
+ VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
+ bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
+ bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
+ bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY;
+ VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+
+ if (modern && !virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+ /* A backend didn't support modern virtio. */
+ if (legacy) {
+ proxy->flags |= VIRTIO_PCI_FLAG_DISABLE_MODERN;
+ modern = false;
+ } else {
+ error_setg(errp, "can't fall back to legacy virtio");
+ return;
+ }
+ }
+ if (modern) {
struct virtio_pci_cap cap = {
.cap_len = sizeof cap,
};
@@ -1672,7 +1730,6 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
struct virtio_pci_cfg_cap *cfg_mask;
- virtio_add_feature(&vdev->host_features, VIRTIO_F_VERSION_1);
virtio_pci_modern_regions_init(proxy);
virtio_pci_modern_mem_region_map(proxy, &proxy->common, &cap);
@@ -1705,40 +1762,6 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
pci_set_long(cfg_mask->pci_cfg_data, ~0x0);
}
- if (proxy->nvectors) {
- int err = msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors,
- proxy->msix_bar);
- if (err) {
- /* Notice when a system that supports MSIx can't initialize it. */
- if (err != -ENOTSUP) {
- error_report("unable to init msix vectors to %" PRIu32,
- proxy->nvectors);
- }
- proxy->nvectors = 0;
- }
- }
-
- proxy->pci_dev.config_write = virtio_write_config;
- proxy->pci_dev.config_read = virtio_read_config;
-
- if (legacy) {
- size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev)
- + virtio_bus_get_vdev_config_len(bus);
- size = pow2ceil(size);
-
- memory_region_init_io(&proxy->bar, OBJECT(proxy),
- &virtio_pci_config_ops,
- proxy, "virtio-pci", size);
-
- pci_register_bar(&proxy->pci_dev, proxy->legacy_io_bar,
- PCI_BASE_ADDRESS_SPACE_IO, &proxy->bar);
- }
-
- if (!kvm_has_many_ioeventfds()) {
- proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
- }
-
- virtio_add_feature(&vdev->host_features, VIRTIO_F_BAD_FEATURE);
}
static void virtio_pci_device_unplugged(DeviceState *d)
@@ -2474,6 +2497,7 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
k->set_guest_notifiers = virtio_pci_set_guest_notifiers;
k->vmstate_change = virtio_pci_vmstate_change;
k->device_plugged = virtio_pci_device_plugged;
+ k->post_plugged = virtio_pci_post_plugged;
k->device_unplugged = virtio_pci_device_unplugged;
k->query_nvectors = virtio_pci_query_nvectors;
}
diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
index 6c3d4cb..3f2c136 100644
--- a/include/hw/virtio/virtio-bus.h
+++ b/include/hw/virtio/virtio-bus.h
@@ -60,6 +60,11 @@ typedef struct VirtioBusClass {
*/
void (*device_plugged)(DeviceState *d, Error **errp);
/*
+ * Re-evaluate setup after feature bits have been validated
+ * by the device backend.
+ */
+ void (*post_plugged)(DeviceState *d, Error **errp);
+ /*
* transport independent exit function.
* This is called by virtio-bus just before the device is unplugged.
*/
--
2.3.9
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH for-2.5] virtio: handle non-virtio-1-capable backend
2015-12-02 14:09 [Qemu-devel] [PATCH for-2.5] virtio: handle non-virtio-1-capable backend Cornelia Huck
@ 2015-12-02 16:43 ` Michael S. Tsirkin
2015-12-02 17:19 ` Cornelia Huck
2015-12-03 9:14 ` Christian Borntraeger
0 siblings, 2 replies; 4+ messages in thread
From: Michael S. Tsirkin @ 2015-12-02 16:43 UTC (permalink / raw)
To: Cornelia Huck; +Cc: borntraeger, jasowang, qemu-devel
On Wed, Dec 02, 2015 at 03:09:58PM +0100, Cornelia Huck wrote:
> If you run a qemu advertising VERSION_1 with an old kernel where
> vhost did not yet support VERSION_1, you'll end up with a device
> that is {modern pci|ccw revision 1} but does not advertise VERSION_1.
> This is not a sensible configuration and is rejected by the Linux
> guest drivers.
>
> To fix this, add a ->post_plugged() callback invoked after features
> have been queried that can handle the VERSION_1 bit being withdrawn
> and change pci (only setup modern if VERSION_1 is still present) and
> ccw (fall back to revision 0 if VERSION_1 is gone).
>
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Unfortunately this is too late: we need to know
whether modern will be supported to know whether
to add the pci express capability :(
Maybe this should be moved into plugged
callback?
> ---
> Michael: I think this should go into 2.5, as otherwise ccw (which
> defaults to virtio-1 with 2.5) will be broken with old host kernels.
> I need someone to give virtio-pci some testing, as I do not have
> a proper setup for that. ccw is working fine.
>
> Changes from initial writeup:
> - Move pci-modern init to post_plugged instead of undoing [Jason]
> - Add a proper patch description + signoff
> - Add some comments
> ---
> hw/s390x/virtio-ccw.c | 12 ++++++
> hw/virtio/virtio-bus.c | 3 ++
> hw/virtio/virtio-pci.c | 96 ++++++++++++++++++++++++++----------------
> include/hw/virtio/virtio-bus.h | 5 +++
> 4 files changed, 80 insertions(+), 36 deletions(-)
>
> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> index fb103b7..63da303 100644
> --- a/hw/s390x/virtio-ccw.c
> +++ b/hw/s390x/virtio-ccw.c
> @@ -1555,6 +1555,17 @@ static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
> d->hotplugged, 1);
> }
>
> +static void virtio_ccw_post_plugged(DeviceState *d, Error **errp)
> +{
> + VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
> + VirtIODevice *vdev = virtio_bus_get_device(&dev->bus);
> +
> + if (!virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> + /* A backend didn't support modern virtio. */
> + dev->max_rev = 0;
> + }
> +}
> +
> static void virtio_ccw_device_unplugged(DeviceState *d)
> {
> VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
> @@ -1891,6 +1902,7 @@ static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data)
> k->save_config = virtio_ccw_save_config;
> k->load_config = virtio_ccw_load_config;
> k->device_plugged = virtio_ccw_device_plugged;
> + k->post_plugged = virtio_ccw_post_plugged;
> k->device_unplugged = virtio_ccw_device_unplugged;
> }
>
> diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
> index febda76..81c7cdd 100644
> --- a/hw/virtio/virtio-bus.c
> +++ b/hw/virtio/virtio-bus.c
> @@ -56,6 +56,9 @@ void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
> assert(vdc->get_features != NULL);
> vdev->host_features = vdc->get_features(vdev, vdev->host_features,
> errp);
> + if (klass->post_plugged != NULL) {
> + klass->post_plugged(qbus->parent, errp);
> + }
> }
>
> /* Reset the virtio_bus */
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index dd48562..af59496 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1626,7 +1626,6 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
> VirtioBusState *bus = &proxy->bus;
> bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
> bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
> - bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY;
> uint8_t *config;
> uint32_t size;
> VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> @@ -1653,6 +1652,65 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
>
>
> if (modern) {
> + virtio_add_feature(&vdev->host_features, VIRTIO_F_VERSION_1);
> + /* Let's see if this feature bit sticks before doing further init. */
> + }
> +
> + if (proxy->nvectors) {
> + int err = msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors,
> + proxy->msix_bar);
> + if (err) {
> + /* Notice when a system that supports MSIx can't initialize it. */
> + if (err != -ENOTSUP) {
> + error_report("unable to init msix vectors to %" PRIu32,
> + proxy->nvectors);
> + }
> + proxy->nvectors = 0;
> + }
> + }
> +
> + proxy->pci_dev.config_write = virtio_write_config;
> + proxy->pci_dev.config_read = virtio_read_config;
> +
> + if (legacy) {
> + size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev)
> + + virtio_bus_get_vdev_config_len(bus);
> + size = pow2ceil(size);
> +
> + memory_region_init_io(&proxy->bar, OBJECT(proxy),
> + &virtio_pci_config_ops,
> + proxy, "virtio-pci", size);
> +
> + pci_register_bar(&proxy->pci_dev, proxy->legacy_io_bar,
> + PCI_BASE_ADDRESS_SPACE_IO, &proxy->bar);
> + }
> +
> + if (!kvm_has_many_ioeventfds()) {
> + proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
> + }
> +
> + virtio_add_feature(&vdev->host_features, VIRTIO_F_BAD_FEATURE);
> +}
> +
> +static void virtio_pci_post_plugged(DeviceState *d, Error **errp)
> +{
> + VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
> + bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
> + bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
> + bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY;
> + VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> +
> + if (modern && !virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> + /* A backend didn't support modern virtio. */
> + if (legacy) {
> + proxy->flags |= VIRTIO_PCI_FLAG_DISABLE_MODERN;
> + modern = false;
> + } else {
> + error_setg(errp, "can't fall back to legacy virtio");
> + return;
> + }
> + }
> + if (modern) {
> struct virtio_pci_cap cap = {
> .cap_len = sizeof cap,
> };
> @@ -1672,7 +1730,6 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
>
> struct virtio_pci_cfg_cap *cfg_mask;
>
> - virtio_add_feature(&vdev->host_features, VIRTIO_F_VERSION_1);
> virtio_pci_modern_regions_init(proxy);
>
> virtio_pci_modern_mem_region_map(proxy, &proxy->common, &cap);
> @@ -1705,40 +1762,6 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
> pci_set_long(cfg_mask->pci_cfg_data, ~0x0);
> }
>
> - if (proxy->nvectors) {
> - int err = msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors,
> - proxy->msix_bar);
> - if (err) {
> - /* Notice when a system that supports MSIx can't initialize it. */
> - if (err != -ENOTSUP) {
> - error_report("unable to init msix vectors to %" PRIu32,
> - proxy->nvectors);
> - }
> - proxy->nvectors = 0;
> - }
> - }
> -
> - proxy->pci_dev.config_write = virtio_write_config;
> - proxy->pci_dev.config_read = virtio_read_config;
> -
> - if (legacy) {
> - size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev)
> - + virtio_bus_get_vdev_config_len(bus);
> - size = pow2ceil(size);
> -
> - memory_region_init_io(&proxy->bar, OBJECT(proxy),
> - &virtio_pci_config_ops,
> - proxy, "virtio-pci", size);
> -
> - pci_register_bar(&proxy->pci_dev, proxy->legacy_io_bar,
> - PCI_BASE_ADDRESS_SPACE_IO, &proxy->bar);
> - }
> -
> - if (!kvm_has_many_ioeventfds()) {
> - proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
> - }
> -
> - virtio_add_feature(&vdev->host_features, VIRTIO_F_BAD_FEATURE);
> }
>
> static void virtio_pci_device_unplugged(DeviceState *d)
> @@ -2474,6 +2497,7 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
> k->set_guest_notifiers = virtio_pci_set_guest_notifiers;
> k->vmstate_change = virtio_pci_vmstate_change;
> k->device_plugged = virtio_pci_device_plugged;
> + k->post_plugged = virtio_pci_post_plugged;
> k->device_unplugged = virtio_pci_device_unplugged;
> k->query_nvectors = virtio_pci_query_nvectors;
> }
> diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
> index 6c3d4cb..3f2c136 100644
> --- a/include/hw/virtio/virtio-bus.h
> +++ b/include/hw/virtio/virtio-bus.h
> @@ -60,6 +60,11 @@ typedef struct VirtioBusClass {
> */
> void (*device_plugged)(DeviceState *d, Error **errp);
> /*
> + * Re-evaluate setup after feature bits have been validated
> + * by the device backend.
> + */
> + void (*post_plugged)(DeviceState *d, Error **errp);
> + /*
> * transport independent exit function.
> * This is called by virtio-bus just before the device is unplugged.
> */
> --
> 2.3.9
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH for-2.5] virtio: handle non-virtio-1-capable backend
2015-12-02 16:43 ` Michael S. Tsirkin
@ 2015-12-02 17:19 ` Cornelia Huck
2015-12-03 9:14 ` Christian Borntraeger
1 sibling, 0 replies; 4+ messages in thread
From: Cornelia Huck @ 2015-12-02 17:19 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: borntraeger, jasowang, qemu-devel
On Wed, 2 Dec 2015 18:43:05 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Wed, Dec 02, 2015 at 03:09:58PM +0100, Cornelia Huck wrote:
> > If you run a qemu advertising VERSION_1 with an old kernel where
> > vhost did not yet support VERSION_1, you'll end up with a device
> > that is {modern pci|ccw revision 1} but does not advertise VERSION_1.
> > This is not a sensible configuration and is rejected by the Linux
> > guest drivers.
> >
> > To fix this, add a ->post_plugged() callback invoked after features
> > have been queried that can handle the VERSION_1 bit being withdrawn
> > and change pci (only setup modern if VERSION_1 is still present) and
> > ccw (fall back to revision 0 if VERSION_1 is gone).
> >
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>
>
> Unfortunately this is too late: we need to know
> whether modern will be supported to know whether
> to add the pci express capability :(
>
> Maybe this should be moved into plugged
> callback?
As discussed on irc: I'll cut this down to ccw only for 2.5, and we'll
rethink for 2.6. Patch in progress.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH for-2.5] virtio: handle non-virtio-1-capable backend
2015-12-02 16:43 ` Michael S. Tsirkin
2015-12-02 17:19 ` Cornelia Huck
@ 2015-12-03 9:14 ` Christian Borntraeger
1 sibling, 0 replies; 4+ messages in thread
From: Christian Borntraeger @ 2015-12-03 9:14 UTC (permalink / raw)
To: Michael S. Tsirkin, Cornelia Huck; +Cc: jasowang, qemu-devel
On 12/02/2015 05:43 PM, Michael S. Tsirkin wrote:
> On Wed, Dec 02, 2015 at 03:09:58PM +0100, Cornelia Huck wrote:
>> If you run a qemu advertising VERSION_1 with an old kernel where
>> vhost did not yet support VERSION_1, you'll end up with a device
>> that is {modern pci|ccw revision 1} but does not advertise VERSION_1.
>> This is not a sensible configuration and is rejected by the Linux
>> guest drivers.
>>
>> To fix this, add a ->post_plugged() callback invoked after features
>> have been queried that can handle the VERSION_1 bit being withdrawn
>> and change pci (only setup modern if VERSION_1 is still present) and
>> ccw (fall back to revision 0 if VERSION_1 is gone).
>>
>> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>
>
> Unfortunately this is too late: we need to know
> whether modern will be supported to know whether
> to add the pci express capability :(
I can at least confirm that this patch "fixes" the guest error message
virtio_net virtio0: virtio: device uses modern interface but does not have VIRTIO_F_VERSION_1
virtio_net: probe of virtio0 failed with error -22
is gone. but yes, its not enough for the other aspects.
>
> Maybe this should be moved into plugged
> callback?
^ permalink raw reply [flat|nested] 4+ messages in thread
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2015-12-02 14:09 [Qemu-devel] [PATCH for-2.5] virtio: handle non-virtio-1-capable backend Cornelia Huck
2015-12-02 16:43 ` Michael S. Tsirkin
2015-12-02 17:19 ` Cornelia Huck
2015-12-03 9:14 ` Christian Borntraeger
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