From 14417039653d3293a795646730a7bf5055d78709 Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Wed, 21 Nov 2012 11:21:18 +0530 Subject: virtio-rng: use virtqueue_get_avail_bytes, fix migration Popping an elem from the vq just to find out its length causes problems with save/load later on. Use the new virtqueue_get_avail_bytes() function instead, saves us the complexity in the migration code, as well as makes the migration endian-safe. Signed-off-by: Amit Shah Reviewed-by: Anthony Liguori Signed-off-by: Anthony Liguori --- hw/virtio-rng.c | 76 +++++++++------------------------------------------------ 1 file changed, 12 insertions(+), 64 deletions(-) diff --git a/hw/virtio-rng.c b/hw/virtio-rng.c index 3ca96c855..6c49bb2e9 100644 --- a/hw/virtio-rng.c +++ b/hw/virtio-rng.c @@ -22,14 +22,10 @@ typedef struct VirtIORNG { /* Only one vq - guest puts buffer(s) on it when it needs entropy */ VirtQueue *vq; - VirtQueueElement elem; /* Config data for the device -- currently only chardev */ VirtIORNGConf *conf; - /* Whether we've popped a vq element into 'elem' above */ - bool popped; - RngBackend *rng; /* We purposefully don't migrate this state. The quota will reset on the @@ -48,17 +44,12 @@ static bool is_guest_ready(VirtIORNG *vrng) return false; } -static size_t pop_an_elem(VirtIORNG *vrng) +static size_t get_request_size(VirtQueue *vq) { - size_t size; + unsigned int in, out; - if (!vrng->popped && !virtqueue_pop(vrng->vq, &vrng->elem)) { - return 0; - } - vrng->popped = true; - - size = iov_size(vrng->elem.in_sg, vrng->elem.in_num); - return size; + virtqueue_get_avail_bytes(vq, &in, &out); + return in; } static void virtio_rng_process(VirtIORNG *vrng); @@ -67,6 +58,7 @@ static void virtio_rng_process(VirtIORNG *vrng); static void chr_read(void *opaque, const void *buf, size_t size) { VirtIORNG *vrng = opaque; + VirtQueueElement elem; size_t len; int offset; @@ -78,15 +70,14 @@ static void chr_read(void *opaque, const void *buf, size_t size) offset = 0; while (offset < size) { - if (!pop_an_elem(vrng)) { + if (!virtqueue_pop(vrng->vq, &elem)) { break; } - len = iov_from_buf(vrng->elem.in_sg, vrng->elem.in_num, + len = iov_from_buf(elem.in_sg, elem.in_num, 0, buf + offset, size - offset); offset += len; - virtqueue_push(vrng->vq, &vrng->elem, len); - vrng->popped = false; + virtqueue_push(vrng->vq, &elem, len); } virtio_notify(&vrng->vdev, vrng->vq); @@ -100,21 +91,19 @@ static void chr_read(void *opaque, const void *buf, size_t size) static void virtio_rng_process(VirtIORNG *vrng) { - ssize_t size; + size_t size; if (!is_guest_ready(vrng)) { return; } - size = pop_an_elem(vrng); + size = get_request_size(vrng->vq); size = MIN(vrng->quota_remaining, size); - - if (size > 0) { + if (size) { rng_backend_request_entropy(vrng->rng, size, chr_read, vrng); } } - static void handle_input(VirtIODevice *vdev, VirtQueue *vq) { VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev); @@ -131,23 +120,6 @@ static void virtio_rng_save(QEMUFile *f, void *opaque) VirtIORNG *vrng = opaque; virtio_save(&vrng->vdev, f); - - qemu_put_byte(f, vrng->popped); - if (vrng->popped) { - int i; - - qemu_put_be32(f, vrng->elem.index); - - qemu_put_be32(f, vrng->elem.in_num); - for (i = 0; i < vrng->elem.in_num; i++) { - qemu_put_be64(f, vrng->elem.in_addr[i]); - } - - qemu_put_be32(f, vrng->elem.out_num); - for (i = 0; i < vrng->elem.out_num; i++) { - qemu_put_be64(f, vrng->elem.out_addr[i]); - } - } } static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id) @@ -159,30 +131,6 @@ static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id) } virtio_load(&vrng->vdev, f); - vrng->popped = qemu_get_byte(f); - if (vrng->popped) { - int i; - - vrng->elem.index = qemu_get_be32(f); - - vrng->elem.in_num = qemu_get_be32(f); - g_assert(vrng->elem.in_num < VIRTQUEUE_MAX_SIZE); - for (i = 0; i < vrng->elem.in_num; i++) { - vrng->elem.in_addr[i] = qemu_get_be64(f); - } - - vrng->elem.out_num = qemu_get_be32(f); - g_assert(vrng->elem.out_num < VIRTQUEUE_MAX_SIZE); - for (i = 0; i < vrng->elem.out_num; i++) { - vrng->elem.out_addr[i] = qemu_get_be64(f); - } - - virtqueue_map_sg(vrng->elem.in_sg, vrng->elem.in_addr, - vrng->elem.in_num, 1); - virtqueue_map_sg(vrng->elem.out_sg, vrng->elem.out_addr, - vrng->elem.out_num, 0); - } - /* We may have an element ready but couldn't process it due to a quota limit. Make sure to try again after live migration when the quota may have been reset. @@ -232,7 +180,7 @@ VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf) vrng->qdev = dev; vrng->conf = conf; - vrng->popped = false; + vrng->quota_remaining = vrng->conf->max_bytes; g_assert_cmpint(vrng->conf->max_bytes, <=, INT64_MAX); -- cgit v1.2.3