kernel/virtio.h

1//2// virtio device definitions.3// for both the mmio interface, and virtio descriptors.4// only tested with qemu.5//6// the virtio spec:7// https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.pdf8//910// virtio mmio control registers, mapped starting at 0x10001000.11// from qemu virtio_mmio.h12#define VIRTIO_MMIO_MAGIC_VALUE		0x000 // 0x7472697613#define VIRTIO_MMIO_VERSION		0x004 // version; should be 214#define VIRTIO_MMIO_DEVICE_ID		0x008 // device type; 1 is net, 2 is disk15#define VIRTIO_MMIO_VENDOR_ID		0x00c // 0x554d455116#define VIRTIO_MMIO_DEVICE_FEATURES	0x01017#define VIRTIO_MMIO_DRIVER_FEATURES	0x02018#define VIRTIO_MMIO_QUEUE_SEL		0x030 // select queue, write-only19#define VIRTIO_MMIO_QUEUE_NUM_MAX	0x034 // max size of current queue, read-only20#define VIRTIO_MMIO_QUEUE_NUM		0x038 // size of current queue, write-only21#define VIRTIO_MMIO_QUEUE_READY		0x044 // ready bit22#define VIRTIO_MMIO_QUEUE_NOTIFY	0x050 // write-only23#define VIRTIO_MMIO_INTERRUPT_STATUS	0x060 // read-only24#define VIRTIO_MMIO_INTERRUPT_ACK	0x064 // write-only25#define VIRTIO_MMIO_STATUS		0x070 // read/write26#define VIRTIO_MMIO_QUEUE_DESC_LOW	0x080 // physical address for descriptor table, write-only27#define VIRTIO_MMIO_QUEUE_DESC_HIGH	0x08428#define VIRTIO_MMIO_DRIVER_DESC_LOW	0x090 // physical address for available ring, write-only29#define VIRTIO_MMIO_DRIVER_DESC_HIGH	0x09430#define VIRTIO_MMIO_DEVICE_DESC_LOW	0x0a0 // physical address for used ring, write-only31#define VIRTIO_MMIO_DEVICE_DESC_HIGH	0x0a43233// status register bits, from qemu virtio_config.h34#define VIRTIO_CONFIG_S_ACKNOWLEDGE	135#define VIRTIO_CONFIG_S_DRIVER		236#define VIRTIO_CONFIG_S_DRIVER_OK	437#define VIRTIO_CONFIG_S_FEATURES_OK	83839// device feature bits40#define VIRTIO_BLK_F_RO              5	/* Disk is read-only */41#define VIRTIO_BLK_F_SCSI            7	/* Supports scsi command passthru */42#define VIRTIO_BLK_F_CONFIG_WCE     11	/* Writeback mode available in config */43#define VIRTIO_BLK_F_MQ             12	/* support more than one vq */44#define VIRTIO_F_ANY_LAYOUT         2745#define VIRTIO_RING_F_INDIRECT_DESC 2846#define VIRTIO_RING_F_EVENT_IDX     294748// this many virtio descriptors.49// must be a power of two.50#define NUM 85152// a single descriptor, from the spec.53struct virtq_desc {54  uint64 addr;55  uint32 len;56  uint16 flags;57  uint16 next;58};59#define VRING_DESC_F_NEXT  1 // chained with another descriptor60#define VRING_DESC_F_WRITE 2 // device writes (vs read)6162// the (entire) avail ring, from the spec.63struct virtq_avail {64  uint16 flags; // always zero65  uint16 idx;   // driver will write ring[idx] next66  uint16 ring[NUM]; // descriptor numbers of chain heads67  uint16 unused;68};6970// one entry in the "used" ring, with which the71// device tells the driver about completed requests.72struct virtq_used_elem {73  uint32 id;   // index of start of completed descriptor chain74  uint32 len;75};7677struct virtq_used {78  uint16 flags; // always zero79  uint16 idx;   // device increments when it adds a ring[] entry80  struct virtq_used_elem ring[NUM];81};8283// these are specific to virtio block devices, e.g. disks,84// described in Section 5.2 of the spec.8586#define VIRTIO_BLK_T_IN  0 // read the disk87#define VIRTIO_BLK_T_OUT 1 // write the disk8889// the format of the first descriptor in a disk request.90// to be followed by two more descriptors containing91// the block, and a one-byte status.92struct virtio_blk_req {93  uint32 type; // VIRTIO_BLK_T_IN or ..._OUT94  uint32 reserved;95  uint64 sector;96};97