From a06b1dae4706fccb9394b35e88d1905dabec85e7 Mon Sep 17 00:00:00 2001 From: Sascha Silbe Date: Tue, 27 Sep 2016 15:43:37 +0200 Subject: [PATCH] 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 Signed-off-by: Sascha Silbe Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/char/virtio-serial-bus.c | 12 +++++++++--- include/hw/compat.h | 4 ++++ include/hw/virtio/virtio-serial.h | 2 ++ 3 files changed, 15 insertions(+), 3 deletions(-) diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c index 57419b2b6a..db2a9f19bc 100644 --- a/hw/char/virtio-serial-bus.c +++ b/hw/char/virtio-serial-bus.c @@ -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(), }; diff --git a/include/hw/compat.h b/include/hw/compat.h index 46412b229a..ef3fae3e1b 100644 --- a/include/hw/compat.h +++ b/include/hw/compat.h @@ -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",\ diff --git a/include/hw/virtio/virtio-serial.h b/include/hw/virtio/virtio-serial.h index 730c88d2a7..b19c44727f 100644 --- a/include/hw/virtio/virtio-serial.h +++ b/include/hw/virtio/virtio-serial.h @@ -184,6 +184,8 @@ struct VirtIOSerial { struct VirtIOSerialPostLoad *post_load; virtio_serial_conf serial; + + uint64_t host_features; }; /* Interface to the virtio-serial bus */