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-rw-r--r--hw/virtio-pci.c194
-rw-r--r--hw/virtio.c14
-rw-r--r--hw/virtio.h1
3 files changed, 184 insertions, 25 deletions
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 13dd39194a..70c40eeb56 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -83,6 +83,11 @@
/* Flags track per-device state like workarounds for quirks in older guests. */
#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG (1 << 0)
+/* Performance improves when virtqueue kick processing is decoupled from the
+ * vcpu thread using ioeventfd for some devices. */
+#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
+#define VIRTIO_PCI_FLAG_USE_IOEVENTFD (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
+
/* QEMU doesn't strictly need write barriers since everything runs in
* lock-step. We'll leave the calls to wmb() in though to make it obvious for
* KVM or if kqemu gets SMP support.
@@ -107,6 +112,8 @@ typedef struct {
/* Max. number of ports we can have for a the virtio-serial device */
uint32_t max_virtserial_ports;
virtio_net_conf net;
+ bool ioeventfd_disabled;
+ bool ioeventfd_started;
} VirtIOPCIProxy;
/* virtio device */
@@ -179,12 +186,132 @@ static int virtio_pci_load_queue(void * opaque, int n, QEMUFile *f)
return 0;
}
+static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
+ int n, bool assign)
+{
+ VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
+ EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
+ int r;
+ if (assign) {
+ r = event_notifier_init(notifier, 1);
+ if (r < 0) {
+ return r;
+ }
+ r = kvm_set_ioeventfd_pio_word(event_notifier_get_fd(notifier),
+ proxy->addr + VIRTIO_PCI_QUEUE_NOTIFY,
+ n, assign);
+ if (r < 0) {
+ event_notifier_cleanup(notifier);
+ }
+ } else {
+ r = kvm_set_ioeventfd_pio_word(event_notifier_get_fd(notifier),
+ proxy->addr + VIRTIO_PCI_QUEUE_NOTIFY,
+ n, assign);
+ if (r < 0) {
+ return r;
+ }
+
+ /* Handle the race condition where the guest kicked and we deassigned
+ * before we got around to handling the kick.
+ */
+ if (event_notifier_test_and_clear(notifier)) {
+ virtio_queue_notify_vq(vq);
+ }
+
+ event_notifier_cleanup(notifier);
+ }
+ return r;
+}
+
+static void virtio_pci_host_notifier_read(void *opaque)
+{
+ VirtQueue *vq = opaque;
+ EventNotifier *n = virtio_queue_get_host_notifier(vq);
+ if (event_notifier_test_and_clear(n)) {
+ virtio_queue_notify_vq(vq);
+ }
+}
+
+static void virtio_pci_set_host_notifier_fd_handler(VirtIOPCIProxy *proxy,
+ int n, bool assign)
+{
+ VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
+ EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
+ if (assign) {
+ qemu_set_fd_handler(event_notifier_get_fd(notifier),
+ virtio_pci_host_notifier_read, NULL, vq);
+ } else {
+ qemu_set_fd_handler(event_notifier_get_fd(notifier),
+ NULL, NULL, NULL);
+ }
+}
+
+static int virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
+{
+ int n, r;
+
+ if (!(proxy->flags & VIRTIO_PCI_FLAG_USE_IOEVENTFD) ||
+ proxy->ioeventfd_disabled ||
+ proxy->ioeventfd_started) {
+ return 0;
+ }
+
+ for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
+ if (!virtio_queue_get_num(proxy->vdev, n)) {
+ continue;
+ }
+
+ r = virtio_pci_set_host_notifier_internal(proxy, n, true);
+ if (r < 0) {
+ goto assign_error;
+ }
+
+ virtio_pci_set_host_notifier_fd_handler(proxy, n, true);
+ }
+ proxy->ioeventfd_started = true;
+ return 0;
+
+assign_error:
+ while (--n >= 0) {
+ if (!virtio_queue_get_num(proxy->vdev, n)) {
+ continue;
+ }
+
+ virtio_pci_set_host_notifier_fd_handler(proxy, n, false);
+ virtio_pci_set_host_notifier_internal(proxy, n, false);
+ }
+ proxy->ioeventfd_started = false;
+ proxy->ioeventfd_disabled = true;
+ return r;
+}
+
+static int virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
+{
+ int n;
+
+ if (!proxy->ioeventfd_started) {
+ return 0;
+ }
+
+ for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
+ if (!virtio_queue_get_num(proxy->vdev, n)) {
+ continue;
+ }
+
+ virtio_pci_set_host_notifier_fd_handler(proxy, n, false);
+ virtio_pci_set_host_notifier_internal(proxy, n, false);
+ }
+ proxy->ioeventfd_started = false;
+ return 0;
+}
+
static void virtio_pci_reset(DeviceState *d)
{
VirtIOPCIProxy *proxy = container_of(d, VirtIOPCIProxy, pci_dev.qdev);
+ virtio_pci_stop_ioeventfd(proxy);
virtio_reset(proxy->vdev);
msix_reset(&proxy->pci_dev);
- proxy->flags = 0;
+ proxy->flags &= ~VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
}
static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
@@ -209,6 +336,7 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
case VIRTIO_PCI_QUEUE_PFN:
pa = (target_phys_addr_t)val << VIRTIO_PCI_QUEUE_ADDR_SHIFT;
if (pa == 0) {
+ virtio_pci_stop_ioeventfd(proxy);
virtio_reset(proxy->vdev);
msix_unuse_all_vectors(&proxy->pci_dev);
}
@@ -223,7 +351,16 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
virtio_queue_notify(vdev, val);
break;
case VIRTIO_PCI_STATUS:
+ if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
+ virtio_pci_stop_ioeventfd(proxy);
+ }
+
virtio_set_status(vdev, val & 0xFF);
+
+ if (val & VIRTIO_CONFIG_S_DRIVER_OK) {
+ virtio_pci_start_ioeventfd(proxy);
+ }
+
if (vdev->status == 0) {
virtio_reset(proxy->vdev);
msix_unuse_all_vectors(&proxy->pci_dev);
@@ -403,6 +540,7 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address,
if (PCI_COMMAND == address) {
if (!(val & PCI_COMMAND_MASTER)) {
if (!(proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG)) {
+ virtio_pci_stop_ioeventfd(proxy);
virtio_set_status(proxy->vdev,
proxy->vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK);
}
@@ -480,30 +618,30 @@ assign_error:
static int virtio_pci_set_host_notifier(void *opaque, int n, bool assign)
{
VirtIOPCIProxy *proxy = opaque;
- VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
- EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
- int r;
+
+ /* Stop using ioeventfd for virtqueue kick if the device starts using host
+ * notifiers. This makes it easy to avoid stepping on each others' toes.
+ */
+ proxy->ioeventfd_disabled = assign;
if (assign) {
- r = event_notifier_init(notifier, 1);
- if (r < 0) {
- return r;
- }
- r = kvm_set_ioeventfd_pio_word(event_notifier_get_fd(notifier),
- proxy->addr + VIRTIO_PCI_QUEUE_NOTIFY,
- n, assign);
- if (r < 0) {
- event_notifier_cleanup(notifier);
- }
+ virtio_pci_stop_ioeventfd(proxy);
+ }
+ /* We don't need to start here: it's not needed because backend
+ * currently only stops on status change away from ok,
+ * reset, vmstop and such. If we do add code to start here,
+ * need to check vmstate, device state etc. */
+ return virtio_pci_set_host_notifier_internal(proxy, n, assign);
+}
+
+static void virtio_pci_vmstate_change(void *opaque, bool running)
+{
+ VirtIOPCIProxy *proxy = opaque;
+
+ if (running) {
+ virtio_pci_start_ioeventfd(proxy);
} else {
- r = kvm_set_ioeventfd_pio_word(event_notifier_get_fd(notifier),
- proxy->addr + VIRTIO_PCI_QUEUE_NOTIFY,
- n, assign);
- if (r < 0) {
- return r;
- }
- event_notifier_cleanup(notifier);
+ virtio_pci_stop_ioeventfd(proxy);
}
- return r;
}
static const VirtIOBindings virtio_pci_bindings = {
@@ -515,6 +653,7 @@ static const VirtIOBindings virtio_pci_bindings = {
.get_features = virtio_pci_get_features,
.set_host_notifier = virtio_pci_set_host_notifier,
.set_guest_notifiers = virtio_pci_set_guest_notifiers,
+ .vmstate_change = virtio_pci_vmstate_change,
};
static void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice *vdev,
@@ -559,10 +698,15 @@ static void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice *vdev,
pci_register_bar(&proxy->pci_dev, 0, size, PCI_BASE_ADDRESS_SPACE_IO,
virtio_map);
+ if (!kvm_has_many_ioeventfds()) {
+ proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
+ }
+
virtio_bind_device(vdev, &virtio_pci_bindings, proxy);
proxy->host_features |= 0x1 << VIRTIO_F_NOTIFY_ON_EMPTY;
proxy->host_features |= 0x1 << VIRTIO_F_BAD_FEATURE;
proxy->host_features = vdev->get_features(vdev, proxy->host_features);
+
}
static int virtio_blk_init_pci(PCIDevice *pci_dev)
@@ -597,6 +741,7 @@ static int virtio_blk_exit_pci(PCIDevice *pci_dev)
{
VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
+ virtio_pci_stop_ioeventfd(proxy);
virtio_blk_exit(proxy->vdev);
blockdev_mark_auto_del(proxy->block.bs);
return virtio_exit_pci(pci_dev);
@@ -658,6 +803,7 @@ static int virtio_net_exit_pci(PCIDevice *pci_dev)
{
VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
+ virtio_pci_stop_ioeventfd(proxy);
virtio_net_exit(proxy->vdev);
return virtio_exit_pci(pci_dev);
}
@@ -705,6 +851,8 @@ static PCIDeviceInfo virtio_info[] = {
.qdev.props = (Property[]) {
DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
DEFINE_BLOCK_PROPERTIES(VirtIOPCIProxy, block),
+ DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
+ VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
DEFINE_VIRTIO_BLK_FEATURES(VirtIOPCIProxy, host_features),
DEFINE_PROP_END_OF_LIST(),
@@ -717,6 +865,8 @@ static PCIDeviceInfo virtio_info[] = {
.exit = virtio_net_exit_pci,
.romfile = "pxe-virtio.bin",
.qdev.props = (Property[]) {
+ DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
+ VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, false),
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3),
DEFINE_VIRTIO_NET_FEATURES(VirtIOPCIProxy, host_features),
DEFINE_NIC_PROPERTIES(VirtIOPCIProxy, nic),
diff --git a/hw/virtio.c b/hw/virtio.c
index 1d20be2ca3..31bd9e32dc 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -575,11 +575,19 @@ int virtio_queue_get_num(VirtIODevice *vdev, int n)
return vdev->vq[n].vring.num;
}
+void virtio_queue_notify_vq(VirtQueue *vq)
+{
+ if (vq->vring.desc) {
+ VirtIODevice *vdev = vq->vdev;
+ trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
+ vq->handle_output(vdev, vq);
+ }
+}
+
void virtio_queue_notify(VirtIODevice *vdev, int n)
{
- if (n < VIRTIO_PCI_QUEUE_MAX && vdev->vq[n].vring.desc) {
- trace_virtio_queue_notify(vdev, n, &vdev->vq[n]);
- vdev->vq[n].handle_output(vdev, &vdev->vq[n]);
+ if (n < VIRTIO_PCI_QUEUE_MAX) {
+ virtio_queue_notify_vq(&vdev->vq[n]);
}
}
diff --git a/hw/virtio.h b/hw/virtio.h
index bd5274225e..d8546d5b30 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -222,5 +222,6 @@ void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx);
VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n);
EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq);
EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
+void virtio_queue_notify_vq(VirtQueue *vq);
void virtio_irq(VirtQueue *vq);
#endif
generated by cgit v1.2.1 (git 2.18.0) at 2024-06-28 15:43:03 +0000