mirror of https://github.com/proxmox/mirror_qemu
virtio-rng: add rate limiting support
This adds parameters to virtio-rng-pci to allow rate limiting the entropy a guest receives. An example command line: $ qemu -device virtio-rng-pci,max-bytes=1024,period=1000 Would limit entropy collection to 1Kb/s. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>master
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16c915ba42
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904d6f5880
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@ -1015,6 +1015,13 @@ static void virtio_rng_initfn(Object *obj)
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static Property virtio_rng_properties[] = {
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static Property virtio_rng_properties[] = {
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DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
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DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
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/* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s. If
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you have an entropy source capable of generating more entropy than this
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and you can pass it through via virtio-rng, then hats off to you. Until
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then, this is unlimited for all practical purposes.
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*/
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DEFINE_PROP_UINT64("max-bytes", VirtIOPCIProxy, rng.max_bytes, INT64_MAX),
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DEFINE_PROP_UINT32("period", VirtIOPCIProxy, rng.period_ms, 1 << 16),
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DEFINE_PROP_END_OF_LIST(),
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DEFINE_PROP_END_OF_LIST(),
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};
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};
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@ -31,6 +31,12 @@ typedef struct VirtIORNG {
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bool popped;
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bool popped;
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RngBackend *rng;
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RngBackend *rng;
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/* We purposefully don't migrate this state. The quota will reset on the
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* destination as a result. Rate limiting is host state, not guest state.
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*/
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QEMUTimer *rate_limit_timer;
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int64_t quota_remaining;
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} VirtIORNG;
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} VirtIORNG;
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static bool is_guest_ready(VirtIORNG *vrng)
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static bool is_guest_ready(VirtIORNG *vrng)
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@ -55,6 +61,8 @@ static size_t pop_an_elem(VirtIORNG *vrng)
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return size;
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return size;
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}
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}
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static void virtio_rng_process(VirtIORNG *vrng);
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/* Send data from a char device over to the guest */
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/* Send data from a char device over to the guest */
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static void chr_read(void *opaque, const void *buf, size_t size)
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static void chr_read(void *opaque, const void *buf, size_t size)
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{
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{
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@ -66,6 +74,8 @@ static void chr_read(void *opaque, const void *buf, size_t size)
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return;
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return;
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}
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}
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vrng->quota_remaining -= size;
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offset = 0;
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offset = 0;
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while (offset < size) {
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while (offset < size) {
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if (!pop_an_elem(vrng)) {
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if (!pop_an_elem(vrng)) {
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@ -85,21 +95,30 @@ static void chr_read(void *opaque, const void *buf, size_t size)
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* didn't have enough data to fill them all, indicate we want more
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* didn't have enough data to fill them all, indicate we want more
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* data.
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* data.
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*/
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*/
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len = pop_an_elem(vrng);
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virtio_rng_process(vrng);
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if (len) {
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}
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static void virtio_rng_process(VirtIORNG *vrng)
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{
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ssize_t size;
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if (!is_guest_ready(vrng)) {
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return;
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}
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size = pop_an_elem(vrng);
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size = MIN(vrng->quota_remaining, size);
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if (size > 0) {
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rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
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rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
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}
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}
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}
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}
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static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
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static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
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{
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{
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VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
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VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
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size_t size;
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virtio_rng_process(vrng);
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size = pop_an_elem(vrng);
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if (size) {
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rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
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}
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}
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}
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static uint32_t get_features(VirtIODevice *vdev, uint32_t f)
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static uint32_t get_features(VirtIODevice *vdev, uint32_t f)
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@ -163,9 +182,27 @@ static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id)
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virtqueue_map_sg(vrng->elem.out_sg, vrng->elem.out_addr,
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virtqueue_map_sg(vrng->elem.out_sg, vrng->elem.out_addr,
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vrng->elem.out_num, 0);
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vrng->elem.out_num, 0);
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}
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}
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/* We may have an element ready but couldn't process it due to a quota
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limit. Make sure to try again after live migration when the quota may
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have been reset.
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*/
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virtio_rng_process(vrng);
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return 0;
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return 0;
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}
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}
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static void check_rate_limit(void *opaque)
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{
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VirtIORNG *s = opaque;
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s->quota_remaining = s->conf->max_bytes;
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virtio_rng_process(s);
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qemu_mod_timer(s->rate_limit_timer,
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qemu_get_clock_ms(vm_clock) + s->conf->period_ms);
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}
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VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf)
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VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf)
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{
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{
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VirtIORNG *vrng;
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VirtIORNG *vrng;
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@ -196,6 +233,16 @@ VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf)
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vrng->qdev = dev;
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vrng->qdev = dev;
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vrng->conf = conf;
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vrng->conf = conf;
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vrng->popped = false;
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vrng->popped = false;
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vrng->quota_remaining = vrng->conf->max_bytes;
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g_assert_cmpint(vrng->conf->max_bytes, <=, INT64_MAX);
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vrng->rate_limit_timer = qemu_new_timer_ms(vm_clock,
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check_rate_limit, vrng);
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qemu_mod_timer(vrng->rate_limit_timer,
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qemu_get_clock_ms(vm_clock) + vrng->conf->period_ms);
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register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save,
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register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save,
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virtio_rng_load, vrng);
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virtio_rng_load, vrng);
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@ -19,6 +19,8 @@
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struct VirtIORNGConf {
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struct VirtIORNGConf {
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RngBackend *rng;
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RngBackend *rng;
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uint64_t max_bytes;
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uint32_t period_ms;
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};
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};
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#endif
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#endif
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