diff options
Diffstat (limited to 'virtio-v1.0-wd01-part1-specification.txt')
| -rw-r--r-- | virtio-v1.0-wd01-part1-specification.txt | 112 |
1 files changed, 108 insertions, 4 deletions
diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt index ba08d49..b9e27ea 100644 --- a/virtio-v1.0-wd01-part1-specification.txt +++ b/virtio-v1.0-wd01-part1-specification.txt @@ -1709,6 +1709,7 @@ virtio: #define CCW_CMD_VDEV_RESET 0x33 #define CCW_CMD_SET_IND 0x43 #define CCW_CMD_SET_CONF_IND 0x53 +#define CCW_CMD_SET_IND_ADAPTER 0x73 #define CCW_CMD_READ_FEAT 0x12 #define CCW_CMD_WRITE_FEAT 0x11 #define CCW_CMD_READ_CONF 0x22 @@ -1842,15 +1843,80 @@ In both cases, the complete configuration space is transmitted. 2.3.3.2.5. Setting Up Indicators -------------------------------- +In order to set up the indicator bits for host->guest notification, +the driver uses different channel commands depending on whether it +wishes to use traditional I/O interrupts tied to a subchannel or +adapter I/O interrupts. For any given device, the two mechanisms +are mutually exclusive. + +For the configuration change indicators, the same mechanism is used +in both cases. + +2.3.3.2.5.1. Setting Up Classic Queue Indicators +------------------------------------------------ + +Indicators for notification via classic I/O interrupts are contained +in a 64 bit value per virtio-ccw proxy device. + To communicate the location of the indicator bits for host->guest notification, the guest uses the CCW_CMD_SET_IND command, pointing to a location containing the guest address of the indicators in a 64 bit value. -For the indicator bits used in the configuration change -host->guest notification, the CCW_CMD_SET_CONF_IND command is -used analogously. +If the driver has already set up two-staged queue indicators via the +CCW_CMD_SET_IND_ADAPTER command, the device MUST post a unit check +with command reject to any subsequent CCW_CMD_SET_IND command. + +2.3.3.2.5.2. Setting Up Configuration Change Indicators +------------------------------------------------------- + +Indicators for configuration change host->guest notification are +contained in a 64 bit value per virtio-ccw proxy device. + +To communicate the location of the indicator bits used in the +configuration change host->guest notification, the driver issues the +CCW_CMD_SET_CONF_IND command, pointing to a location containing the +guest address of the indicators in a 64 bit value. + +2.3.3.2.5.3. Setting Up Two-Stage Queue Indicators +-------------------------------------------------- + +Indicators for notification via adapter I/O interrupts consist of +two stages: +- a summary indicator byte covering the virtqueues for one or more + virtio-ccw proxy devices +- a set of contigous indicator bits for the virtqueues for a + virtio-ccw proxy device + +To communicate the location of the summary and queue indicator bits, +the driver uses the CCW_CMD_SET_IND_ADAPTER command with the following +payload: + +struct virtio_thinint_area { + __u64 summary_indicator; + __u64 indicator; + __u64 bit_nr; + __u8 isc; +} __attribute__ ((packed)); + +summary_indicator contains the guest address of the 8 bit summary +indicator. +indicator contains the guest address of an area wherin the indicators +for the devices are contained, starting at bit_nr, one bit per +virtqueue of the device. Bit numbers start at the left. +isc contains the I/O interruption subclass to be used for the adapter +I/O interrupt. It may be different from the isc used by the proxy +virtio-ccw device's subchannel. +If the driver has already set up classic queue indicators via the +CCW_CMD_SET_IND command, the device MUST post a unit check with +command reject to any subsequent CCW_CMD_SET_IND_ADAPTER command. + +2.3.3.2.5.4. Legacy Interfaces: A Note on Setting Up Indicators +--------------------------------------------------------------- + +Legacy devices will only support classic queue indicators; they will +reject CCW_CMD_SET_IND_ADAPTER as they don't know that command. 2.3.3.3. Device Operation ------------------------- @@ -1858,6 +1924,21 @@ used analogously. 2.3.3.3.1. Host->Guest Notification ----------------------------------- +There are two modes of operation regarding host->guest notifcation, +classic I/O interrupts and adapter I/O interrupts. The mode to be +used is determined by the driver by using CCW_CMD_SET_IND respectively +CCW_CMD_SET_IND_ADAPTER to set up queue indicators. + +For configuration changes, the driver will always use classic I/O +interrupts. + +2.3.3.3.1.1. Notification via Classic I/O Interrupts +---------------------------------------------------- + +If the driver used the CCW_CMD_SET_IND command to set up queue +indicators, the device will use classic I/O interrupts for +host->guest notification about virtqueue activity. + For notifying the guest of virtqueue buffers, the host sets the corresponding bit in the guest-provided indicators. If an interrupt is not already pending for the subchannel, the host @@ -1865,7 +1946,30 @@ generates an unsolicited I/O interrupt. If the host wants to notify the guest about configuration changes, it sets bit 0 in the configuration indicators and -generates an unsolicited I/O interrupt, if needed. +generates an unsolicited I/O interrupt, if needed. This also +applies if adapter I/O interrupts are used for queue notifications. + +2.3.3.3.1.2. Notification via Adapter I/O Interrupts +---------------------------------------------------- + +If the driver used the CCW_CMD_SET_IND_ADAPTER command to set up +queue indicators, the device will use adapter I/O interrupts for +host->guest notification about virtqueue activity. + +For notifying the guest of virtqueue buffers, the host sets the +bit in the guest-provided indicator area at the corresponding offset. +The guest-provided summary indicator is also set. An adapter I/O +interrupt for the corresponding interruption subclass is generated. +The device SHOULD only generate an adapter I/O interrupt if the +summary indicator had not been set prior to notification. The driver +MUST clear the summary indicator after receiving an adapter I/O +interrupt before it processes the queue indicators. + +2.3.3.3.1.3. Legacy Interfaces: A Note on Host->Guest Notification +------------------------------------------------------------------ + +As legacy devices and drivers support only classic queue indicators, +host->guest notification will always be done via classic I/O interrupts. 2.3.3.3.2. Guest->Host Notification ----------------------------------- |