Jason Wang
2022-Feb-08 09:02 UTC
[PATCH 06/31] vhost: Route guest->host notification through shadow virtqueue
? 2022/1/31 ??7:33, Eugenio Perez Martin ??:> On Fri, Jan 28, 2022 at 7:57 AM Jason Wang <jasowang at redhat.com> wrote: >> >> ? 2022/1/22 ??4:27, Eugenio P?rez ??: >>> At this moment no buffer forwarding will be performed in SVQ mode: Qemu >>> just forward the guest's kicks to the device. This commit also set up >>> SVQs in the vhost device. >>> >>> Host memory notifiers regions are left out for simplicity, and they will >>> not be addressed in this series. >> >> I wonder if it's better to squash this into patch 5 since it gives us a >> full guest->host forwarding. >> > I'm fine with that if you think it makes the review easier.Yes please.> >>> Signed-off-by: Eugenio P?rez <eperezma at redhat.com> >>> --- >>> include/hw/virtio/vhost-vdpa.h | 4 ++ >>> hw/virtio/vhost-vdpa.c | 122 ++++++++++++++++++++++++++++++++- >>> 2 files changed, 124 insertions(+), 2 deletions(-) >>> >>> 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-vdpa.c b/hw/virtio/vhost-vdpa.c >>> index 6c10a7f05f..18de14f0fb 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 >>> @@ -409,8 +411,14 @@ 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) { >>> + /* SVQ is not compatible with host notifiers mr */ >> >> I guess there should be a TODO or FIXME here. >> > Sure I can add it. > >>> + return; >>> + } >>> + >>> for (i = dev->vq_index; i < dev->vq_index + dev->nvqs; i++) { >>> if (vhost_vdpa_host_notifier_init(dev, i)) { >>> goto err; >>> @@ -424,6 +432,17 @@ err: >>> return; >>> } >>> >>> +static void vhost_vdpa_svq_cleanup(struct vhost_dev *dev) >>> +{ >>> + struct vhost_vdpa *v = dev->opaque; >>> + size_t idx; >>> + >>> + 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; >>> @@ -432,6 +451,7 @@ 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); >>> @@ -507,9 +527,15 @@ static int vhost_vdpa_get_device_id(struct vhost_dev *dev, >>> >>> static int vhost_vdpa_reset_device(struct vhost_dev *dev) >>> { >>> + struct vhost_vdpa *v = dev->opaque; >>> int ret; >>> uint8_t status = 0; >>> >>> + for (unsigned i = 0; i < v->shadow_vqs->len; ++i) { >>> + VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, i); >>> + vhost_svq_stop(svq); >>> + } >>> + >>> ret = vhost_vdpa_call(dev, VHOST_VDPA_SET_STATUS, &status); >>> trace_vhost_vdpa_reset_device(dev, status); >>> return ret; >>> @@ -639,13 +665,28 @@ static int vhost_vdpa_get_vring_base(struct vhost_dev *dev, >>> return ret; >>> } >>> >>> -static int vhost_vdpa_set_vring_kick(struct vhost_dev *dev, >>> - struct vhost_vring_file *file) >>> +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); >>> } >>> >>> +static int vhost_vdpa_set_vring_kick(struct vhost_dev *dev, >>> + struct vhost_vring_file *file) >>> +{ >>> + struct vhost_vdpa *v = dev->opaque; >>> + int vdpa_idx = vhost_vdpa_get_vq_index(dev, file->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, >>> struct vhost_vring_file *file) >>> { >>> @@ -653,6 +694,33 @@ static int vhost_vdpa_set_vring_call(struct vhost_dev *dev, >>> return vhost_vdpa_call(dev, VHOST_SET_VRING_CALL, file); >>> } >>> >>> +/** >>> + * Set 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 >>> + */ >>> +static bool vhost_vdpa_svq_setup(struct vhost_dev *dev, >>> + VhostShadowVirtqueue *svq, >>> + unsigned idx) >>> +{ >>> + struct vhost_vring_file file = { >>> + .index = dev->vq_index + idx, >>> + }; >>> + const EventNotifier *event_notifier; >>> + int r; >>> + >>> + event_notifier = vhost_svq_get_dev_kick_notifier(svq); >> >> A question, any reason for making VhostShadowVirtqueue private? If we >> export it in .h we don't need helper to access its member like >> vhost_svq_get_dev_kick_notifier(). >> > To export it it's always a possibility of course, but that direct > access will not be thread safe if we decide to move SVQ to its own > iothread for example.I don't get this, maybe you can give me an example.> > I feel it will be easier to work with it this way but it might be that > I'm just used to making as much as possible private. Not like it's > needed to use the helpers in the hot paths, only in the setup and > teardown. > >> Note that vhost_dev is a public structure. >> > Sure we could embed in vhost_virtqueue if we choose to do it that way, > for example. > >>> + file.fd = event_notifier_get_fd(event_notifier); >>> + r = vhost_vdpa_set_vring_dev_kick(dev, &file); >>> + if (unlikely(r != 0)) { >>> + error_report("Can't set device kick fd (%d)", -r); >>> + } >> >> I wonder whether or not we can generalize the logic here and >> vhost_vdpa_set_vring_kick(). There's nothing vdpa specific unless the >> vhost_ops->set_vring_kick(). >> > If we call vhost_ops->set_vring_kick we are setting guest->SVQ kick > notifier, not SVQ -> vDPA device, because the > if(v->shadow_vqs_enabled). All of the modified ops callbacks are > hiding the actual device from the vhost subsystem so we need to > explicitly use the newly created _dev_ ones.Ok, I'm fine to start with vhost_vdpa specific code.> >>> + >>> + return r == 0; >>> +} >>> + >>> static int vhost_vdpa_dev_start(struct vhost_dev *dev, bool started) >>> { >>> struct vhost_vdpa *v = dev->opaque; >>> @@ -660,6 +728,13 @@ static int vhost_vdpa_dev_start(struct vhost_dev *dev, bool started) >>> >>> if (started) { >>> vhost_vdpa_host_notifiers_init(dev); >>> + for (unsigned 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); >>> + if (unlikely(!ok)) { >>> + return -1; >>> + } >>> + } >>> vhost_vdpa_set_vring_ready(dev); >>> } else { >>> vhost_vdpa_host_notifiers_uninit(dev, dev->nvqs); >>> @@ -737,6 +812,41 @@ static bool vhost_vdpa_force_iommu(struct vhost_dev *dev) >>> return true; >>> } >>> >>> +/** >>> + * Adaptor function to free shadow virtqueue through gpointer >>> + * >>> + * @svq The Shadow Virtqueue >>> + */ >>> +static void vhost_psvq_free(gpointer svq) >>> +{ >>> + vhost_svq_free(svq); >>> +} >> >> Any reason for such indirection? Can we simply use vhost_svq_free()? >> > GCC complains about different types. I think we could do a function > type cast and it's valid for every architecture qemu supports, but the > indirection seems cleaner to me, and I would be surprised if the > compiler does not optimize it away in the cases that the casting are > valid. > > ../hw/virtio/vhost-vdpa.c:1186:60: error: incompatible function > pointer types passing 'void (VhostShadowVirtqueue *)' (aka 'void > (struct VhostShadowVirtqueue *)') to parameter of type > 'GDestroyNotify' (aka 'void (*)(void *)')Or just change vhost_svq_free() to take gpointer instead? Then we don't need a cast. Thanks> > Thanks! > >> Thanks >> >> >>> + >>> +static int vhost_vdpa_init_svq(struct vhost_dev *hdev, struct vhost_vdpa *v, >>> + Error **errp) >>> +{ >>> + size_t n_svqs = v->shadow_vqs_enabled ? hdev->nvqs : 0; >>> + g_autoptr(GPtrArray) shadow_vqs = g_ptr_array_new_full(n_svqs, >>> + vhost_psvq_free); >>> + if (!v->shadow_vqs_enabled) { >>> + goto out; >>> + } >>> + >>> + for (unsigned n = 0; n < hdev->nvqs; ++n) { >>> + VhostShadowVirtqueue *svq = vhost_svq_new(); >>> + >>> + if (unlikely(!svq)) { >>> + error_setg(errp, "Cannot create svq %u", n); >>> + return -1; >>> + } >>> + g_ptr_array_add(v->shadow_vqs, svq); >>> + } >>> + >>> +out: >>> + 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; >>> @@ -759,6 +869,10 @@ 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); >>> >>> @@ -770,6 +884,10 @@ 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; >>> } >>> >>> const VhostOps vdpa_ops = {