diff options
Diffstat (limited to 'hw/virtio.c')
| -rw-r--r-- | hw/virtio.c | 97 |
1 files changed, 85 insertions, 12 deletions
diff --git a/hw/virtio.c b/hw/virtio.c index 6e8814cb64..e6043de827 100644 --- a/hw/virtio.c +++ b/hw/virtio.c @@ -71,7 +71,17 @@ struct VirtQueue VRing vring; target_phys_addr_t pa; uint16_t last_avail_idx; + /* Last used index value we have signalled on */ + uint16_t signalled_used; + + /* Last used index value we have signalled on */ + bool signalled_used_valid; + + /* Notification enabled? */ + bool notification; + int inuse; + uint16_t vector; void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq); VirtIODevice *vdev; @@ -140,6 +150,11 @@ static inline uint16_t vring_avail_ring(VirtQueue *vq, int i) return lduw_phys(pa); } +static inline uint16_t vring_used_event(VirtQueue *vq) +{ + return vring_avail_ring(vq, vq->vring.num); +} + static inline void vring_used_ring_id(VirtQueue *vq, int i, uint32_t val) { target_phys_addr_t pa; @@ -161,11 +176,11 @@ static uint16_t vring_used_idx(VirtQueue *vq) return lduw_phys(pa); } -static inline void vring_used_idx_increment(VirtQueue *vq, uint16_t val) +static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val) { target_phys_addr_t pa; pa = vq->vring.used + offsetof(VRingUsed, idx); - stw_phys(pa, vring_used_idx(vq) + val); + stw_phys(pa, val); } static inline void vring_used_flags_set_bit(VirtQueue *vq, int mask) @@ -182,12 +197,26 @@ static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask) stw_phys(pa, lduw_phys(pa) & ~mask); } +static inline void vring_avail_event(VirtQueue *vq, uint16_t val) +{ + target_phys_addr_t pa; + if (!vq->notification) { + return; + } + pa = vq->vring.used + offsetof(VRingUsed, ring[vq->vring.num]); + stw_phys(pa, val); +} + void virtio_queue_set_notification(VirtQueue *vq, int enable) { - if (enable) + vq->notification = enable; + if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) { + vring_avail_event(vq, vring_avail_idx(vq)); + } else if (enable) { vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY); - else + } else { vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY); + } } int virtio_queue_ready(VirtQueue *vq) @@ -233,11 +262,16 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem, void virtqueue_flush(VirtQueue *vq, unsigned int count) { + uint16_t old, new; /* Make sure buffer is written before we update index. */ wmb(); trace_virtqueue_flush(vq, count); - vring_used_idx_increment(vq, count); + old = vring_used_idx(vq); + new = old + count; + vring_used_idx_set(vq, new); vq->inuse -= count; + if (unlikely((int16_t)(new - vq->signalled_used) < (uint16_t)(new - old))) + vq->signalled_used_valid = false; } void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem, @@ -394,6 +428,9 @@ int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem) max = vq->vring.num; i = head = virtqueue_get_head(vq, vq->last_avail_idx++); + if (vq->vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) { + vring_avail_event(vq, vring_avail_idx(vq)); + } if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) { if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) { @@ -477,6 +514,9 @@ void virtio_reset(void *opaque) vdev->vq[i].last_avail_idx = 0; vdev->vq[i].pa = 0; vdev->vq[i].vector = VIRTIO_NO_VECTOR; + vdev->vq[i].signalled_used = 0; + vdev->vq[i].signalled_used_valid = false; + vdev->vq[i].notification = true; } } @@ -585,9 +625,7 @@ void virtio_queue_notify_vq(VirtQueue *vq) void virtio_queue_notify(VirtIODevice *vdev, int n) { - if (n < VIRTIO_PCI_QUEUE_MAX) { - virtio_queue_notify_vq(&vdev->vq[n]); - } + virtio_queue_notify_vq(&vdev->vq[n]); } uint16_t virtio_queue_vector(VirtIODevice *vdev, int n) @@ -628,13 +666,45 @@ void virtio_irq(VirtQueue *vq) virtio_notify_vector(vq->vdev, vq->vector); } -void virtio_notify(VirtIODevice *vdev, VirtQueue *vq) +/* Assuming a given event_idx value from the other size, if + * we have just incremented index from old to new_idx, + * should we trigger an event? */ +static inline int vring_need_event(uint16_t event, uint16_t new, uint16_t old) +{ + /* Note: Xen has similar logic for notification hold-off + * in include/xen/interface/io/ring.h with req_event and req_prod + * corresponding to event_idx + 1 and new respectively. + * Note also that req_event and req_prod in Xen start at 1, + * event indexes in virtio start at 0. */ + return (uint16_t)(new - event - 1) < (uint16_t)(new - old); +} + +static bool vring_notify(VirtIODevice *vdev, VirtQueue *vq) { + uint16_t old, new; + bool v; /* Always notify when queue is empty (when feature acknowledge) */ - if ((vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT) && - (!(vdev->guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) || - (vq->inuse || vring_avail_idx(vq) != vq->last_avail_idx))) + if (((vdev->guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) && + !vq->inuse && vring_avail_idx(vq) == vq->last_avail_idx)) { + return true; + } + + if (!(vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX))) { + return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT); + } + + v = vq->signalled_used_valid; + vq->signalled_used_valid = true; + old = vq->signalled_used; + new = vq->signalled_used = vring_used_idx(vq); + return !v || vring_need_event(vring_used_event(vq), new, old); +} + +void virtio_notify(VirtIODevice *vdev, VirtQueue *vq) +{ + if (!vring_notify(vdev, vq)) { return; + } trace_virtio_notify(vdev, vq); vdev->isr |= 0x01; @@ -717,6 +787,8 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f) vdev->vq[i].vring.num = qemu_get_be32(f); vdev->vq[i].pa = qemu_get_be64(f); qemu_get_be16s(f, &vdev->vq[i].last_avail_idx); + vdev->vq[i].signalled_used_valid = false; + vdev->vq[i].notification = true; if (vdev->vq[i].pa) { uint16_t nheads; @@ -789,6 +861,7 @@ VirtIODevice *virtio_common_init(const char *name, uint16_t device_id, vdev->queue_sel = 0; vdev->config_vector = VIRTIO_NO_VECTOR; vdev->vq = qemu_mallocz(sizeof(VirtQueue) * VIRTIO_PCI_QUEUE_MAX); + vdev->vm_running = vm_running; for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) { vdev->vq[i].vector = VIRTIO_NO_VECTOR; vdev->vq[i].vdev = vdev; |