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virtio-bus: Plug devices after features are negotiated 

Currently, devices are plugged before features are negotiated.
If the backend doesn't support VIRTIO_F_VERSION_1, the transport
needs to rewind some settings.

This is the case for CCW, for which a post_plugged callback had
been introduced, where max_rev field is just updated if
VIRTIO_F_VERSION_1 is not supported by the backend.
For PCI, implementing post_plugged would be much more
complicated, so it needs to know whether the backend supports
VIRTIO_F_VERSION_1 at plug time.

Currently, nothing is done for PCI. Modern capabilities get
exposed to the guest even if VIRTIO_F_VERSION_1 is not supported
by the backend, which confuses the guest.

This patch replaces existing post_plugged solution with an
approach that fits with both transports.
Features negotiation is performed before ->device_plugged() call.
A pre_plugged callback is introduced so that the transports can
set their supported features.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: qemu-stable@nongnu.org
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com> [ccw]
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
This commit is contained in:
Maxime Coquelin 2016-09-13 15:30:30 +02:00 committed by Michael S. Tsirkin
parent d1eb8f2acb
commit d1b4259f1a
5 changed files with 62 additions and 28 deletions
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30
hw/s390x/virtio-ccw.c
View File

@ -1261,6 +1261,16 @@ static int virtio_ccw_load_config(DeviceState *d, QEMUFile *f)
return 0;
}
static void virtio_ccw_pre_plugged(DeviceState *d, Error **errp)
{
VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
VirtIODevice *vdev = virtio_bus_get_device(&dev->bus);
if (dev->max_rev >= 1) {
virtio_add_feature(&vdev->host_features, VIRTIO_F_VERSION_1);
}
}
/* This is called by virtio-bus just after the device is plugged. */
static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
{
@ -1270,6 +1280,10 @@ static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
SubchDev *sch = ccw_dev->sch;
int n = virtio_get_num_queues(vdev);
if (!virtio_has_feature(vdev->host_features, VIRTIO_F_VERSION_1)) {
dev->max_rev = 0;
}
if (virtio_get_num_queues(vdev) > VIRTIO_CCW_QUEUE_MAX) {
error_setg(errp, "The number of virtqueues %d "
"exceeds ccw limit %d", n,
@ -1283,25 +1297,11 @@ static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
sch->id.cu_model = virtio_bus_get_vdev_id(&dev->bus);
if (dev->max_rev >= 1) {
virtio_add_feature(&vdev->host_features, VIRTIO_F_VERSION_1);
}
css_generate_sch_crws(sch->cssid, sch->ssid, sch->schid,
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);
@ -1593,8 +1593,8 @@ static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data)
k->load_queue = virtio_ccw_load_queue;
k->save_config = virtio_ccw_save_config;
k->load_config = virtio_ccw_load_config;
k->pre_plugged = virtio_ccw_pre_plugged;
k->device_plugged = virtio_ccw_device_plugged;
k->post_plugged = virtio_ccw_post_plugged;
k->device_unplugged = virtio_ccw_device_unplugged;
k->ioeventfd_started = virtio_ccw_ioeventfd_started;
k->ioeventfd_set_started = virtio_ccw_ioeventfd_set_started;

9
hw/virtio/virtio-bus.c
View File

@ -49,16 +49,17 @@ void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
DPRINTF("%s: plug device.\n", qbus->name);
if (klass->device_plugged != NULL) {
klass->device_plugged(qbus->parent, errp);
if (klass->pre_plugged != NULL) {
klass->pre_plugged(qbus->parent, errp);
}
/* Get the features of the plugged device. */
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);
if (klass->device_plugged != NULL) {
klass->device_plugged(qbus->parent, errp);
}
}

36
hw/virtio/virtio-pci.c
View File

@ -1576,18 +1576,48 @@ static void virtio_pci_modern_io_region_unmap(VirtIOPCIProxy *proxy,
&region->mr);
}
static void virtio_pci_pre_plugged(DeviceState *d, Error **errp)
{
VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
if (virtio_pci_modern(proxy)) {
virtio_add_feature(&vdev->host_features, VIRTIO_F_VERSION_1);
}
virtio_add_feature(&vdev->host_features, VIRTIO_F_BAD_FEATURE);
}
/* This is called by virtio-bus just after the device is plugged. */
static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
{
VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
VirtioBusState *bus = &proxy->bus;
bool legacy = virtio_pci_legacy(proxy);
bool modern = virtio_pci_modern(proxy);
bool 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);
/*
* Virtio capabilities present without
* VIRTIO_F_VERSION_1 confuses guests
*/
if (!virtio_has_feature(vdev->host_features, VIRTIO_F_VERSION_1)) {
virtio_pci_disable_modern(proxy);
if (!legacy) {
error_setg(errp, "Device doesn't support modern mode, and legacy"
" mode is disabled");
error_append_hint(errp, "Set disable-legacy to off\n");
return;
}
}
modern = virtio_pci_modern(proxy);
config = proxy->pci_dev.config;
if (proxy->class_code) {
pci_config_set_class(config, proxy->class_code);
@ -1629,7 +1659,6 @@ 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);
@ -1694,8 +1723,6 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
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)
@ -2508,6 +2535,7 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
k->query_guest_notifiers = virtio_pci_query_guest_notifiers;
k->set_guest_notifiers = virtio_pci_set_guest_notifiers;
k->vmstate_change = virtio_pci_vmstate_change;
k->pre_plugged = virtio_pci_pre_plugged;
k->device_plugged = virtio_pci_device_plugged;
k->device_unplugged = virtio_pci_device_unplugged;
k->query_nvectors = virtio_pci_query_nvectors;

5
hw/virtio/virtio-pci.h
View File

@ -181,6 +181,11 @@ static inline void virtio_pci_force_virtio_1(VirtIOPCIProxy *proxy)
proxy->disable_legacy = ON_OFF_AUTO_ON;
}
static inline void virtio_pci_disable_modern(VirtIOPCIProxy *proxy)
{
proxy->disable_modern = true;
}
/*
* virtio-scsi-pci: This extends VirtioPCIProxy.
*/

10
include/hw/virtio/virtio-bus.h
View File

@ -53,16 +53,16 @@ typedef struct VirtioBusClass {
bool (*query_guest_notifiers)(DeviceState *d);
int (*set_guest_notifiers)(DeviceState *d, int nvqs, bool assign);
void (*vmstate_change)(DeviceState *d, bool running);
/*
* Expose the features the transport layer supports before
* the negotiation takes place.
*/
void (*pre_plugged)(DeviceState *d, Error **errp);
/*
* transport independent init function.
* This is called by virtio-bus just after the device is plugged.
*/
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.