diff options
| -rw-r--r-- | hw/virtio-pci.c | 7 | ||||
| -rw-r--r-- | hw/virtio-rng.c | 63 | ||||
| -rw-r--r-- | hw/virtio-rng.h | 2 |
3 files changed, 64 insertions, 8 deletions
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index a3d4777e8d..f90296d672 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -1015,6 +1015,13 @@ static void virtio_rng_initfn(Object *obj) static Property virtio_rng_properties[] = { DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features), + /* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s. If + you have an entropy source capable of generating more entropy than this + and you can pass it through via virtio-rng, then hats off to you. Until + then, this is unlimited for all practical purposes. + */ + DEFINE_PROP_UINT64("max-bytes", VirtIOPCIProxy, rng.max_bytes, INT64_MAX), + DEFINE_PROP_UINT32("period", VirtIOPCIProxy, rng.period_ms, 1 << 16), DEFINE_PROP_END_OF_LIST(), }; diff --git a/hw/virtio-rng.c b/hw/virtio-rng.c index b7fb5e9d61..3ca96c855f 100644 --- a/hw/virtio-rng.c +++ b/hw/virtio-rng.c @@ -31,6 +31,12 @@ typedef struct VirtIORNG { bool popped; RngBackend *rng; + + /* We purposefully don't migrate this state. The quota will reset on the + * destination as a result. Rate limiting is host state, not guest state. + */ + QEMUTimer *rate_limit_timer; + int64_t quota_remaining; } VirtIORNG; static bool is_guest_ready(VirtIORNG *vrng) @@ -55,6 +61,8 @@ static size_t pop_an_elem(VirtIORNG *vrng) return size; } +static void virtio_rng_process(VirtIORNG *vrng); + /* Send data from a char device over to the guest */ static void chr_read(void *opaque, const void *buf, size_t size) { @@ -66,6 +74,8 @@ static void chr_read(void *opaque, const void *buf, size_t size) return; } + vrng->quota_remaining -= size; + offset = 0; while (offset < size) { if (!pop_an_elem(vrng)) { @@ -85,23 +95,32 @@ static void chr_read(void *opaque, const void *buf, size_t size) * didn't have enough data to fill them all, indicate we want more * data. */ - len = pop_an_elem(vrng); - if (len) { - rng_backend_request_entropy(vrng->rng, size, chr_read, vrng); - } + virtio_rng_process(vrng); } -static void handle_input(VirtIODevice *vdev, VirtQueue *vq) +static void virtio_rng_process(VirtIORNG *vrng) { - VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev); - size_t size; + ssize_t size; + + if (!is_guest_ready(vrng)) { + return; + } size = pop_an_elem(vrng); - if (size) { + size = MIN(vrng->quota_remaining, size); + + if (size > 0) { 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); + virtio_rng_process(vrng); +} + static uint32_t get_features(VirtIODevice *vdev, uint32_t f) { return f; @@ -163,9 +182,27 @@ static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id) 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. + */ + virtio_rng_process(vrng); + return 0; } +static void check_rate_limit(void *opaque) +{ + VirtIORNG *s = opaque; + + s->quota_remaining = s->conf->max_bytes; + virtio_rng_process(s); + qemu_mod_timer(s->rate_limit_timer, + qemu_get_clock_ms(vm_clock) + s->conf->period_ms); +} + + VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf) { VirtIORNG *vrng; @@ -196,6 +233,16 @@ 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); + + vrng->rate_limit_timer = qemu_new_timer_ms(vm_clock, + check_rate_limit, vrng); + + qemu_mod_timer(vrng->rate_limit_timer, + qemu_get_clock_ms(vm_clock) + vrng->conf->period_ms); + register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save, virtio_rng_load, vrng); diff --git a/hw/virtio-rng.h b/hw/virtio-rng.h index fbb01048ba..7324d0ab57 100644 --- a/hw/virtio-rng.h +++ b/hw/virtio-rng.h @@ -19,6 +19,8 @@ struct VirtIORNGConf { RngBackend *rng; + uint64_t max_bytes; + uint32_t period_ms; }; #endif |