On Mon, Feb 28, 2022 at 3:57 AM Jason Wang <jasow...@redhat.com> wrote:
>
>
> 在 2022/2/27 下午9:40, Eugenio Pérez 写道:
> > At this mode no buffer forwarding will be performed in SVQ mode: Qemu
> > will just forward the guest's kicks to the device.
> >
> > Host memory notifiers regions are left out for simplicity, and they will
> > not be addressed in this series.
> >
> > Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> > ---
> > hw/virtio/vhost-shadow-virtqueue.h | 14 +++
> > include/hw/virtio/vhost-vdpa.h | 4 +
> > hw/virtio/vhost-shadow-virtqueue.c | 52 +++++++++++
> > hw/virtio/vhost-vdpa.c | 145 ++++++++++++++++++++++++++++-
> > 4 files changed, 213 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/virtio/vhost-shadow-virtqueue.h
> > b/hw/virtio/vhost-shadow-virtqueue.h
> > index f1519e3c7b..1cbc87d5d8 100644
> > --- a/hw/virtio/vhost-shadow-virtqueue.h
> > +++ b/hw/virtio/vhost-shadow-virtqueue.h
> > @@ -18,8 +18,22 @@ typedef struct VhostShadowVirtqueue {
> > EventNotifier hdev_kick;
> > /* Shadow call notifier, sent to vhost */
> > EventNotifier hdev_call;
> > +
> > + /*
> > + * Borrowed virtqueue's guest to host notifier. To borrow it in this
> > event
> > + * notifier allows to recover the VhostShadowVirtqueue from the event
> > loop
> > + * easily. If we use the VirtQueue's one, we don't have an easy way to
> > + * retrieve VhostShadowVirtqueue.
> > + *
> > + * So shadow virtqueue must not clean it, or we would lose VirtQueue
> > one.
> > + */
> > + EventNotifier svq_kick;
> > } VhostShadowVirtqueue;
> >
> > +void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
> > +
> > +void vhost_svq_stop(VhostShadowVirtqueue *svq);
> > +
> > VhostShadowVirtqueue *vhost_svq_new(void);
> >
> > void vhost_svq_free(gpointer vq);
> > diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
> > index 3ce79a646d..009a9f3b6b 100644
> > --- a/include/hw/virtio/vhost-vdpa.h
> > +++ b/include/hw/virtio/vhost-vdpa.h
> > @@ -12,6 +12,8 @@
> > #ifndef HW_VIRTIO_VHOST_VDPA_H
> > #define HW_VIRTIO_VHOST_VDPA_H
> >
> > +#include <gmodule.h>
> > +
> > #include "hw/virtio/virtio.h"
> > #include "standard-headers/linux/vhost_types.h"
> >
> > @@ -27,6 +29,8 @@ typedef struct vhost_vdpa {
> > bool iotlb_batch_begin_sent;
> > MemoryListener listener;
> > struct vhost_vdpa_iova_range iova_range;
> > + bool shadow_vqs_enabled;
> > + GPtrArray *shadow_vqs;
> > struct vhost_dev *dev;
> > VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
> > } VhostVDPA;
> > diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> > b/hw/virtio/vhost-shadow-virtqueue.c
> > index 019cf1950f..a5d0659f86 100644
> > --- a/hw/virtio/vhost-shadow-virtqueue.c
> > +++ b/hw/virtio/vhost-shadow-virtqueue.c
> > @@ -11,6 +11,56 @@
> > #include "hw/virtio/vhost-shadow-virtqueue.h"
> >
> > #include "qemu/error-report.h"
> > +#include "qemu/main-loop.h"
> > +#include "linux-headers/linux/vhost.h"
> > +
> > +/** Forward guest notifications */
> > +static void vhost_handle_guest_kick(EventNotifier *n)
> > +{
> > + VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue,
> > + svq_kick);
> > + event_notifier_test_and_clear(n);
> > + event_notifier_set(&svq->hdev_kick);
> > +}
> > +
> > +/**
> > + * Set a new file descriptor for the guest to kick the SVQ and notify for
> > avail
> > + *
> > + * @svq The svq
> > + * @svq_kick_fd The svq kick fd
> > + *
> > + * Note that the SVQ will never close the old file descriptor.
> > + */
> > +void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd)
> > +{
> > + EventNotifier *svq_kick = &svq->svq_kick;
> > + bool poll_stop = VHOST_FILE_UNBIND != event_notifier_get_fd(svq_kick);
>
>
> I wonder if this is robust. E.g is there any chance that may end up with
> both poll_stop and poll_start are false?
>
I cannot make that happen in qemu, but the function supports that case
well: It will do nothing. It's more or less the same code as used in
the vhost kernel, and is the expected behaviour if you send two
VHOST_FILE_UNBIND one right after another to me.
> If not, can we simple detect poll_stop as below and treat !poll_start
> and poll_stop?
>
I'm not sure what does it add. Is there an unexpected consequence with
the current do-nothing behavior I've missed?
Thanks!
> Other looks good.
>
> Thanks
>
>
> > + bool poll_start = svq_kick_fd != VHOST_FILE_UNBIND;
> > +
> > + if (poll_stop) {
> > + event_notifier_set_handler(svq_kick, NULL);
> > + }
> > +
> > + /*
> > + * event_notifier_set_handler already checks for guest's notifications
> > if
> > + * they arrive at the new file descriptor in the switch, so there is no
> > + * need to explicitly check for them.
> > + */
> > + if (poll_start) {
> > + event_notifier_init_fd(svq_kick, svq_kick_fd);
> > + event_notifier_set(svq_kick);
> > + event_notifier_set_handler(svq_kick, vhost_handle_guest_kick);
> > + }
> > +}
> > +
> > +/**
> > + * Stop the shadow virtqueue operation.
> > + * @svq Shadow Virtqueue
> > + */
> > +void vhost_svq_stop(VhostShadowVirtqueue *svq)
> > +{
> > + event_notifier_set_handler(&svq->svq_kick, NULL);
> > +}
> >
> > /**
> > * Creates vhost shadow virtqueue, and instructs the vhost device to use
> > the
> > @@ -39,6 +89,7 @@ VhostShadowVirtqueue *vhost_svq_new(void)
> > goto err_init_hdev_call;
> > }
> >
> > + event_notifier_init_fd(&svq->svq_kick, VHOST_FILE_UNBIND);
> > return g_steal_pointer(&svq);
> >
> > err_init_hdev_call:
> > @@ -56,6 +107,7 @@ err_init_hdev_kick:
> > void vhost_svq_free(gpointer pvq)
> > {
> > VhostShadowVirtqueue *vq = pvq;
> > + vhost_svq_stop(vq);
> > event_notifier_cleanup(&vq->hdev_kick);
> > event_notifier_cleanup(&vq->hdev_call);
> > g_free(vq);
> > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> > index 04ea43704f..454bf50735 100644
> > --- a/hw/virtio/vhost-vdpa.c
> > +++ b/hw/virtio/vhost-vdpa.c
> > @@ -17,12 +17,14 @@
> > #include "hw/virtio/vhost.h"
> > #include "hw/virtio/vhost-backend.h"
> > #include "hw/virtio/virtio-net.h"
> > +#include "hw/virtio/vhost-shadow-virtqueue.h"
> > #include "hw/virtio/vhost-vdpa.h"
> > #include "exec/address-spaces.h"
> > #include "qemu/main-loop.h"
> > #include "cpu.h"
> > #include "trace.h"
> > #include "qemu-common.h"
> > +#include "qapi/error.h"
> >
> > /*
> > * Return one past the end of the end of section. Be careful with uint64_t
> > @@ -342,6 +344,30 @@ static bool vhost_vdpa_one_time_request(struct
> > vhost_dev *dev)
> > return v->index != 0;
> > }
> >
> > +static int vhost_vdpa_init_svq(struct vhost_dev *hdev, struct vhost_vdpa
> > *v,
> > + Error **errp)
> > +{
> > + g_autoptr(GPtrArray) shadow_vqs = NULL;
> > +
> > + if (!v->shadow_vqs_enabled) {
> > + return 0;
> > + }
> > +
> > + shadow_vqs = g_ptr_array_new_full(hdev->nvqs, vhost_svq_free);
> > + for (unsigned n = 0; n < hdev->nvqs; ++n) {
> > + g_autoptr(VhostShadowVirtqueue) svq = vhost_svq_new();
> > +
> > + if (unlikely(!svq)) {
> > + error_setg(errp, "Cannot create svq %u", n);
> > + return -1;
> > + }
> > + g_ptr_array_add(shadow_vqs, g_steal_pointer(&svq));
> > + }
> > +
> > + v->shadow_vqs = g_steal_pointer(&shadow_vqs);
> > + return 0;
> > +}
> > +
> > static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error
> > **errp)
> > {
> > struct vhost_vdpa *v;
> > @@ -364,6 +390,10 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void
> > *opaque, Error **errp)
> > dev->opaque = opaque ;
> > v->listener = vhost_vdpa_memory_listener;
> > v->msg_type = VHOST_IOTLB_MSG_V2;
> > + ret = vhost_vdpa_init_svq(dev, v, errp);
> > + if (ret) {
> > + goto err;
> > + }
> >
> > vhost_vdpa_get_iova_range(v);
> >
> > @@ -375,6 +405,10 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void
> > *opaque, Error **errp)
> > VIRTIO_CONFIG_S_DRIVER);
> >
> > return 0;
> > +
> > +err:
> > + ram_block_discard_disable(false);
> > + return ret;
> > }
> >
> > static void vhost_vdpa_host_notifier_uninit(struct vhost_dev *dev,
> > @@ -444,8 +478,14 @@ err:
> >
> > static void vhost_vdpa_host_notifiers_init(struct vhost_dev *dev)
> > {
> > + struct vhost_vdpa *v = dev->opaque;
> > int i;
> >
> > + if (v->shadow_vqs_enabled) {
> > + /* FIXME SVQ is not compatible with host notifiers mr */
> > + return;
> > + }
> > +
> > for (i = dev->vq_index; i < dev->vq_index + dev->nvqs; i++) {
> > if (vhost_vdpa_host_notifier_init(dev, i)) {
> > goto err;
> > @@ -459,6 +499,21 @@ err:
> > return;
> > }
> >
> > +static void vhost_vdpa_svq_cleanup(struct vhost_dev *dev)
> > +{
> > + struct vhost_vdpa *v = dev->opaque;
> > + size_t idx;
> > +
> > + if (!v->shadow_vqs) {
> > + return;
> > + }
> > +
> > + for (idx = 0; idx < v->shadow_vqs->len; ++idx) {
> > + vhost_svq_stop(g_ptr_array_index(v->shadow_vqs, idx));
> > + }
> > + g_ptr_array_free(v->shadow_vqs, true);
> > +}
> > +
> > static int vhost_vdpa_cleanup(struct vhost_dev *dev)
> > {
> > struct vhost_vdpa *v;
> > @@ -467,6 +522,7 @@ static int vhost_vdpa_cleanup(struct vhost_dev *dev)
> > trace_vhost_vdpa_cleanup(dev, v);
> > vhost_vdpa_host_notifiers_uninit(dev, dev->nvqs);
> > memory_listener_unregister(&v->listener);
> > + vhost_vdpa_svq_cleanup(dev);
> >
> > dev->opaque = NULL;
> > ram_block_discard_disable(false);
> > @@ -558,11 +614,26 @@ static int vhost_vdpa_get_device_id(struct vhost_dev
> > *dev,
> > return ret;
> > }
> >
> > +static void vhost_vdpa_reset_svq(struct vhost_vdpa *v)
> > +{
> > + if (!v->shadow_vqs_enabled) {
> > + return;
> > + }
> > +
> > + for (unsigned i = 0; i < v->shadow_vqs->len; ++i) {
> > + VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, i);
> > + vhost_svq_stop(svq);
> > + }
> > +}
> > +
> > static int vhost_vdpa_reset_device(struct vhost_dev *dev)
> > {
> > + struct vhost_vdpa *v = dev->opaque;
> > int ret;
> > uint8_t status = 0;
> >
> > + vhost_vdpa_reset_svq(v);
> > +
> > ret = vhost_vdpa_call(dev, VHOST_VDPA_SET_STATUS, &status);
> > trace_vhost_vdpa_reset_device(dev, status);
> > return ret;
> > @@ -646,13 +717,75 @@ static int vhost_vdpa_get_config(struct vhost_dev
> > *dev, uint8_t *config,
> > return ret;
> > }
> >
> > +static int vhost_vdpa_set_vring_dev_kick(struct vhost_dev *dev,
> > + struct vhost_vring_file *file)
> > +{
> > + trace_vhost_vdpa_set_vring_kick(dev, file->index, file->fd);
> > + return vhost_vdpa_call(dev, VHOST_SET_VRING_KICK, file);
> > +}
> > +
> > +/**
> > + * Set the shadow virtqueue descriptors to the device
> > + *
> > + * @dev The vhost device model
> > + * @svq The shadow virtqueue
> > + * @idx The index of the virtqueue in the vhost device
> > + * @errp Error
> > + */
> > +static bool vhost_vdpa_svq_setup(struct vhost_dev *dev,
> > + VhostShadowVirtqueue *svq,
> > + unsigned idx,
> > + Error **errp)
> > +{
> > + struct vhost_vring_file file = {
> > + .index = dev->vq_index + idx,
> > + };
> > + const EventNotifier *event_notifier = &svq->hdev_kick;
> > + int r;
> > +
> > + file.fd = event_notifier_get_fd(event_notifier);
> > + r = vhost_vdpa_set_vring_dev_kick(dev, &file);
> > + if (unlikely(r != 0)) {
> > + error_setg_errno(errp, -r, "Can't set device kick fd");
> > + }
> > +
> > + return r == 0;
> > +}
> > +
> > +static bool vhost_vdpa_svqs_start(struct vhost_dev *dev)
> > +{
> > + struct vhost_vdpa *v = dev->opaque;
> > + Error *err = NULL;
> > + unsigned i;
> > +
> > + if (!v->shadow_vqs) {
> > + return true;
> > + }
> > +
> > + for (i = 0; i < v->shadow_vqs->len; ++i) {
> > + VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, i);
> > + bool ok = vhost_vdpa_svq_setup(dev, svq, i, &err);
> > + if (unlikely(!ok)) {
> > + error_reportf_err(err, "Cannot setup SVQ %u: ", i);
> > + return false;
> > + }
> > + }
> > +
> > + return true;
> > +}
> > +
> > static int vhost_vdpa_dev_start(struct vhost_dev *dev, bool started)
> > {
> > struct vhost_vdpa *v = dev->opaque;
> > + bool ok;
> > trace_vhost_vdpa_dev_start(dev, started);
> >
> > if (started) {
> > vhost_vdpa_host_notifiers_init(dev);
> > + ok = vhost_vdpa_svqs_start(dev);
> > + if (unlikely(!ok)) {
> > + return -1;
> > + }
> > vhost_vdpa_set_vring_ready(dev);
> > } else {
> > vhost_vdpa_host_notifiers_uninit(dev, dev->nvqs);
> > @@ -724,8 +857,16 @@ static int vhost_vdpa_get_vring_base(struct vhost_dev
> > *dev,
> > static int vhost_vdpa_set_vring_kick(struct vhost_dev *dev,
> > struct vhost_vring_file *file)
> > {
> > - trace_vhost_vdpa_set_vring_kick(dev, file->index, file->fd);
> > - return vhost_vdpa_call(dev, VHOST_SET_VRING_KICK, file);
> > + struct vhost_vdpa *v = dev->opaque;
> > + int vdpa_idx = file->index - dev->vq_index;
> > +
> > + if (v->shadow_vqs_enabled) {
> > + VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs,
> > vdpa_idx);
> > + vhost_svq_set_svq_kick_fd(svq, file->fd);
> > + return 0;
> > + } else {
> > + return vhost_vdpa_set_vring_dev_kick(dev, file);
> > + }
> > }
> >
> > static int vhost_vdpa_set_vring_call(struct vhost_dev *dev,
>
