virtio-mmio: ioeventfd support
set_host_notifier and set_guest_notifiers supported by virtio-mmio now. Most code copied from virtio-pci. This makes it possible to use vhost-net with virtio-mmio, improving performance by about 30%. The kvm-arm does not yet support irqfd, need to fix the hard-coded part after kvm-arm gets irqfd support. Signed-off-by: Ying-Shiuan Pan <yingshiuan.pan@gmail.com> Signed-off-by: Pavel Fedin <p.fedin@samsung.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Ying-Shiuan Pan
Michael S. Tsirkin
parent
afcf905cff
commit
434027badb
@ -22,7 +22,9 @@
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#include "hw/sysbus.h"
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#include "hw/virtio/virtio.h"
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#include "qemu/host-utils.h"
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#include "sysemu/kvm.h"
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#include "hw/virtio/virtio-bus.h"
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#include "qemu/error-report.h"
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/* #define DEBUG_VIRTIO_MMIO */
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@ -86,8 +88,96 @@ typedef struct {
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uint32_t guest_page_shift;
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/* virtio-bus */
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VirtioBusState bus;
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bool ioeventfd_disabled;
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bool ioeventfd_started;
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} VirtIOMMIOProxy;
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static int virtio_mmio_set_host_notifier_internal(VirtIOMMIOProxy *proxy,
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int n, bool assign,
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bool set_handler)
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{
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VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
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VirtQueue *vq = virtio_get_queue(vdev, n);
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EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
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int r = 0;
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if (assign) {
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r = event_notifier_init(notifier, 1);
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if (r < 0) {
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error_report("%s: unable to init event notifier: %d",
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__func__, r);
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return r;
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}
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virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
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memory_region_add_eventfd(&proxy->iomem, VIRTIO_MMIO_QUEUENOTIFY, 4,
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true, n, notifier);
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} else {
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memory_region_del_eventfd(&proxy->iomem, VIRTIO_MMIO_QUEUENOTIFY, 4,
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true, n, notifier);
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virtio_queue_set_host_notifier_fd_handler(vq, false, false);
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event_notifier_cleanup(notifier);
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}
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return r;
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}
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static void virtio_mmio_start_ioeventfd(VirtIOMMIOProxy *proxy)
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{
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VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
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int n, r;
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if (!kvm_eventfds_enabled() ||
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proxy->ioeventfd_disabled ||
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proxy->ioeventfd_started) {
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return;
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}
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for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
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if (!virtio_queue_get_num(vdev, n)) {
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continue;
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}
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r = virtio_mmio_set_host_notifier_internal(proxy, n, true, true);
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if (r < 0) {
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goto assign_error;
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}
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}
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proxy->ioeventfd_started = true;
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return;
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assign_error:
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while (--n >= 0) {
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if (!virtio_queue_get_num(vdev, n)) {
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continue;
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}
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r = virtio_mmio_set_host_notifier_internal(proxy, n, false, false);
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assert(r >= 0);
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}
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proxy->ioeventfd_started = false;
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error_report("%s: failed. Fallback to a userspace (slower).", __func__);
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}
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static void virtio_mmio_stop_ioeventfd(VirtIOMMIOProxy *proxy)
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{
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int r;
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int n;
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VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
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if (!proxy->ioeventfd_started) {
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return;
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}
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for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
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if (!virtio_queue_get_num(vdev, n)) {
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continue;
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}
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r = virtio_mmio_set_host_notifier_internal(proxy, n, false, false);
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assert(r >= 0);
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}
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proxy->ioeventfd_started = false;
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}
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static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size)
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{
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VirtIOMMIOProxy *proxy = (VirtIOMMIOProxy *)opaque;
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@ -265,7 +355,16 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, uint64_t value,
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virtio_update_irq(vdev);
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break;
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case VIRTIO_MMIO_STATUS:
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if (!(value & VIRTIO_CONFIG_S_DRIVER_OK)) {
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virtio_mmio_stop_ioeventfd(proxy);
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}
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virtio_set_status(vdev, value & 0xff);
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if (value & VIRTIO_CONFIG_S_DRIVER_OK) {
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virtio_mmio_start_ioeventfd(proxy);
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}
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if (vdev->status == 0) {
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virtio_reset(vdev);
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}
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@ -328,12 +427,92 @@ static void virtio_mmio_reset(DeviceState *d)
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{
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VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
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virtio_mmio_stop_ioeventfd(proxy);
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virtio_bus_reset(&proxy->bus);
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proxy->host_features_sel = 0;
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proxy->guest_features_sel = 0;
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proxy->guest_page_shift = 0;
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}
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static int virtio_mmio_set_guest_notifier(DeviceState *d, int n, bool assign,
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bool with_irqfd)
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{
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VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
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VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
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VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
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VirtQueue *vq = virtio_get_queue(vdev, n);
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EventNotifier *notifier = virtio_queue_get_guest_notifier(vq);
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if (assign) {
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int r = event_notifier_init(notifier, 0);
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if (r < 0) {
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return r;
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}
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virtio_queue_set_guest_notifier_fd_handler(vq, true, with_irqfd);
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} else {
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virtio_queue_set_guest_notifier_fd_handler(vq, false, with_irqfd);
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event_notifier_cleanup(notifier);
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}
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if (vdc->guest_notifier_mask) {
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vdc->guest_notifier_mask(vdev, n, !assign);
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}
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return 0;
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}
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static int virtio_mmio_set_guest_notifiers(DeviceState *d, int nvqs,
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bool assign)
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{
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VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
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VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
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/* TODO: need to check if kvm-arm supports irqfd */
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bool with_irqfd = false;
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int r, n;
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nvqs = MIN(nvqs, VIRTIO_QUEUE_MAX);
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for (n = 0; n < nvqs; n++) {
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if (!virtio_queue_get_num(vdev, n)) {
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break;
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}
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r = virtio_mmio_set_guest_notifier(d, n, assign, with_irqfd);
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if (r < 0) {
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goto assign_error;
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}
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}
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return 0;
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assign_error:
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/* We get here on assignment failure. Recover by undoing for VQs 0 .. n. */
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assert(assign);
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while (--n >= 0) {
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virtio_mmio_set_guest_notifier(d, n, !assign, false);
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}
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return r;
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}
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static int virtio_mmio_set_host_notifier(DeviceState *opaque, int n,
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bool assign)
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{
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VirtIOMMIOProxy *proxy = VIRTIO_MMIO(opaque);
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/* Stop using ioeventfd for virtqueue kick if the device starts using host
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* notifiers. This makes it easy to avoid stepping on each others' toes.
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*/
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proxy->ioeventfd_disabled = assign;
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if (assign) {
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virtio_mmio_stop_ioeventfd(proxy);
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}
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/* We don't need to start here: it's not needed because backend
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* currently only stops on status change away from ok,
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* reset, vmstop and such. If we do add code to start here,
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* need to check vmstate, device state etc. */
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return virtio_mmio_set_host_notifier_internal(proxy, n, assign, false);
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}
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/* virtio-mmio device */
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static void virtio_mmio_realizefn(DeviceState *d, Error **errp)
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@ -375,6 +554,8 @@ static void virtio_mmio_bus_class_init(ObjectClass *klass, void *data)
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k->notify = virtio_mmio_update_irq;
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k->save_config = virtio_mmio_save_config;
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k->load_config = virtio_mmio_load_config;
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k->set_host_notifier = virtio_mmio_set_host_notifier;
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k->set_guest_notifiers = virtio_mmio_set_guest_notifiers;
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k->has_variable_vring_alignment = true;
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bus_class->max_dev = 1;
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}
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