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virtio-serial: enable virtio console emergency write feature 

Add support for enabling the virtio 1.0 "emergency write"
(VIRTIO_CONSOLE_F_EMERG_WRITE) feature. The previous patch introduced
the plumbing required for this; now we expose the virtio feature to
the guest. The feature is disabled for compatibility machines to avoid
exposing a new feature to existing guests.

As required by the virtio 1.0 spec, the emergency write functionality
is available to the guest even if the guest doesn't negotatiate the
feature, as well as before feature negotation.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Sascha Silbe 2016-09-27 15:43:37 +02:00 committed by Michael S. Tsirkin
parent 09da01c3f2
commit a06b1dae47
3 changed files with 15 additions and 3 deletions
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12
hw/char/virtio-serial-bus.c
View File

@ -541,6 +541,7 @@ static uint64_t get_features(VirtIODevice *vdev, uint64_t features,
vser = VIRTIO_SERIAL(vdev);
features |= vser->host_features;
if (vser->bus.max_nr_ports > 1) {
virtio_add_feature(&features, VIRTIO_CONSOLE_F_MULTIPORT);
}
@ -1003,6 +1004,7 @@ static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOSerial *vser = VIRTIO_SERIAL(dev);
uint32_t i, max_supported_ports;
size_t config_size = sizeof(struct virtio_console_config);
if (!vser->serial.max_virtserial_ports) {
error_setg(errp, "Maximum number of serial ports not specified");
@ -1017,10 +1019,12 @@ static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
return;
}
/* We don't support emergency write, skip it for now. */
/* TODO: cleaner fix, depending on host features. */
if (!virtio_has_feature(vser->host_features,
VIRTIO_CONSOLE_F_EMERG_WRITE)) {
config_size = offsetof(struct virtio_console_config, emerg_wr);
}
virtio_init(vdev, "virtio-serial", VIRTIO_ID_CONSOLE,
offsetof(struct virtio_console_config, emerg_wr));
config_size);
/* Spawn a new virtio-serial bus on which the ports will ride as devices */
qbus_create_inplace(&vser->bus, sizeof(vser->bus), TYPE_VIRTIO_SERIAL_BUS,
@ -1116,6 +1120,8 @@ VMSTATE_VIRTIO_DEVICE(console, 3, virtio_serial_load, virtio_vmstate_save);
static Property virtio_serial_properties[] = {
DEFINE_PROP_UINT32("max_ports", VirtIOSerial, serial.max_virtserial_ports,
31),
DEFINE_PROP_BIT64("emergency-write", VirtIOSerial, host_features,
VIRTIO_CONSOLE_F_EMERG_WRITE, true),
DEFINE_PROP_END_OF_LIST(),
};

4
include/hw/compat.h
View File

@ -6,6 +6,10 @@
.driver = "virtio-pci",\
.property = "page-per-vq",\
.value = "on",\
},{\
.driver = "virtio-serial-device",\
.property = "emergency-write",\
.value = "off",\
},{\
.driver = "ioapic",\
.property = "version",\

2
include/hw/virtio/virtio-serial.h
View File

@ -184,6 +184,8 @@ struct VirtIOSerial {
struct VirtIOSerialPostLoad *post_load;
virtio_serial_conf serial;
uint64_t host_features;
};
/* Interface to the virtio-serial bus */