| Message ID | 1530596284-4101-9-git-send-email-jasowang@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jul 03, 2018 at 01:38:04PM +0800, Jason Wang wrote: > This patch introduces support for event suppression. This is done by > have a two areas: device area and driver area. One side could then try > to disable or enable (delayed) notification from other side by using a > boolean hint or event index interface in the areas. > > For more information, please refer Virtio spec. > > Signed-off-by: Jason Wang <jasowang@redhat.com> > --- > drivers/vhost/vhost.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++---- > drivers/vhost/vhost.h | 10 ++- > 2 files changed, 185 insertions(+), 16 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 0f3f07c..cccbc82 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -1115,10 +1115,15 @@ static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num, > struct vring_used __user *used) > { > struct vring_desc_packed *packed = (struct vring_desc_packed *)desc; > + struct vring_packed_desc_event *driver_event = > + (struct vring_packed_desc_event *)avail; > + struct vring_packed_desc_event *device_event = > + (struct vring_packed_desc_event *)used; > > - /* TODO: check device area and driver area */ > return access_ok(VERIFY_READ, packed, num * sizeof(*packed)) && > - access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)); > + access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)) && R/W parameter doesn't make sense to most architectures and the comment in x86 says WRITE is a superset of READ, is it possible to converge them here? /** * access_ok: - Checks if a user space pointer is valid * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe * to write to a block, it is always safe to read from it. * @addr: User space pointer to start of block to check * @size: Size of block to check * * Context: User context only. This function may sleep if pagefaults are * enabled. * * Checks if a pointer to a block of memory in user space is valid. * * Returns true (nonzero) if the memory block may be valid, false (zero) * if it is definitely invalid. * * Note that, depending on architecture, this function probably just * checks that the pointer is in the user space range - after calling * this function, memory access functions may still return -EFAULT. */ #define access_ok(type, addr, size) ...... Thanks, Wei > + access_ok(VERIFY_READ, driver_event, sizeof(*driver_event)) && > + access_ok(VERIFY_WRITE, device_event, sizeof(*device_event)); > } > > static int vq_access_ok_split(struct vhost_virtqueue *vq, unsigned int num, > @@ -1193,14 +1198,27 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq, > return true; > } > > -int vq_iotlb_prefetch(struct vhost_virtqueue *vq) > +int vq_iotlb_prefetch_packed(struct vhost_virtqueue *vq) > +{ > + int num = vq->num; > + > + return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc, > + num * sizeof(*vq->desc), VHOST_ADDR_DESC) && > + iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->desc, > + num * sizeof(*vq->desc), VHOST_ADDR_DESC) && > + iotlb_access_ok(vq, VHOST_ACCESS_RO, > + (u64)(uintptr_t)vq->driver_event, > + sizeof(*vq->driver_event), VHOST_ADDR_AVAIL) && > + iotlb_access_ok(vq, VHOST_ACCESS_WO, > + (u64)(uintptr_t)vq->device_event, > + sizeof(*vq->device_event), VHOST_ADDR_USED); > +} > + > +int vq_iotlb_prefetch_split(struct vhost_virtqueue *vq) > { > size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; > unsigned int num = vq->num; > > - if (!vq->iotlb) > - return 1; > - > return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc, > num * sizeof(*vq->desc), VHOST_ADDR_DESC) && > iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail, > @@ -1212,6 +1230,17 @@ int vq_iotlb_prefetch(struct vhost_virtqueue *vq) > num * sizeof(*vq->used->ring) + s, > VHOST_ADDR_USED); > } > + > +int vq_iotlb_prefetch(struct vhost_virtqueue *vq) > +{ > + if (!vq->iotlb) > + return 1; > + > + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) > + return vq_iotlb_prefetch_packed(vq); > + else > + return vq_iotlb_prefetch_split(vq); > +} > EXPORT_SYMBOL_GPL(vq_iotlb_prefetch); > > /* Can we log writes? */ > @@ -1771,6 +1800,50 @@ static int vhost_update_used_flags(struct vhost_virtqueue *vq) > return 0; > } > > +static int vhost_update_device_flags(struct vhost_virtqueue *vq, > + __virtio16 device_flags) > +{ > + void __user *flags; > + > + if (vhost_put_user(vq, device_flags, &vq->device_event->flags, > + VHOST_ADDR_USED) < 0) > + return -EFAULT; > + if (unlikely(vq->log_used)) { > + /* Make sure the flag is seen before log. */ > + smp_wmb(); > + /* Log used flag write. */ > + flags = &vq->device_event->flags; > + log_write(vq->log_base, vq->log_addr + > + (flags - (void __user *)vq->device_event), > + sizeof(vq->device_event->flags)); > + if (vq->log_ctx) > + eventfd_signal(vq->log_ctx, 1); > + } > + return 0; > +} > + > +static int vhost_update_device_off_wrap(struct vhost_virtqueue *vq, > + __virtio16 device_off_wrap) > +{ > + void __user *off_wrap; > + > + if (vhost_put_user(vq, device_off_wrap, &vq->device_event->off_wrap, > + VHOST_ADDR_USED) < 0) > + return -EFAULT; > + if (unlikely(vq->log_used)) { > + /* Make sure the flag is seen before log. */ > + smp_wmb(); > + /* Log used flag write. */ > + off_wrap = &vq->device_event->off_wrap; > + log_write(vq->log_base, vq->log_addr + > + (off_wrap - (void __user *)vq->device_event), > + sizeof(vq->device_event->off_wrap)); > + if (vq->log_ctx) > + eventfd_signal(vq->log_ctx, 1); > + } > + return 0; > +} > + > static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) > { > if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx), > @@ -2756,16 +2829,13 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, > } > EXPORT_SYMBOL_GPL(vhost_add_used_n); > > -static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) > +static bool vhost_notify_split(struct vhost_dev *dev, > + struct vhost_virtqueue *vq) > { > __u16 old, new; > __virtio16 event; > bool v; > > - /* TODO: check driver area */ > - if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) > - return true; > - > /* Flush out used index updates. This is paired > * with the barrier that the Guest executes when enabling > * interrupts. */ > @@ -2798,6 +2868,64 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) > return vring_need_event(vhost16_to_cpu(vq, event), new, old); > } > > +static bool vhost_notify_packed(struct vhost_dev *dev, > + struct vhost_virtqueue *vq) > +{ > + __virtio16 event_off_wrap, event_flags; > + __u16 old, new, off_wrap; > + bool v; > + > + /* Flush out used descriptors updates. This is paired > + * with the barrier that the Guest executes when enabling > + * interrupts. > + */ > + smp_mb(); > + > + if (vhost_get_avail(vq, event_flags, > + &vq->driver_event->flags) < 0) { > + vq_err(vq, "Failed to get driver desc_event_flags"); > + return true; > + } > + > + if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) > + return event_flags != > + cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE); > + > + old = vq->signalled_used; > + v = vq->signalled_used_valid; > + new = vq->signalled_used = vq->last_used_idx; > + vq->signalled_used_valid = true; > + > + if (event_flags != cpu_to_vhost16(vq, RING_EVENT_FLAGS_DESC)) > + return event_flags != > + cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE); > + > + /* Read desc event flags before event_off and event_wrap */ > + smp_rmb(); > + > + if (vhost_get_avail(vq, event_off_wrap, > + &vq->driver_event->off_wrap) < 0) { > + vq_err(vq, "Failed to get driver desc_event_off/wrap"); > + return true; > + } > + > + off_wrap = vhost16_to_cpu(vq, event_off_wrap); > + > + if (unlikely(!v)) > + return true; > + > + return vhost_vring_packed_need_event(vq, vq->last_used_wrap_counter, > + off_wrap, new, old); > +} > + > +static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) > +{ > + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) > + return vhost_notify_packed(dev, vq); > + else > + return vhost_notify_split(dev, vq); > +} > + > /* This actually signals the guest, using eventfd. */ > void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) > { > @@ -2875,10 +3003,34 @@ static bool vhost_enable_notify_packed(struct vhost_dev *dev, > struct vhost_virtqueue *vq) > { > struct vring_desc_packed *d = vq->desc_packed + vq->avail_idx; > - __virtio16 flags; > + __virtio16 flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_ENABLE); > int ret; > > - /* TODO: enable notification through device area */ > + if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) > + return false; > + vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; > + > + if (vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { > + __virtio16 off_wrap = cpu_to_vhost16(vq, vq->avail_idx | > + vq->avail_wrap_counter << 15); > + > + ret = vhost_update_device_off_wrap(vq, off_wrap); > + if (ret) { > + vq_err(vq, "Failed to write to off warp at %p: %d\n", > + &vq->device_event->off_wrap, ret); > + return false; > + } > + /* Make sure off_wrap is wrote before flags */ > + smp_wmb(); > + flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_DESC); > + } > + > + ret = vhost_update_device_flags(vq, flags); > + if (ret) { > + vq_err(vq, "Failed to enable notification at %p: %d\n", > + &vq->device_event->flags, ret); > + return false; > + } > > /* They could have slipped one in as we were doing that: make > * sure it's written, then check again. > @@ -2945,7 +3097,18 @@ EXPORT_SYMBOL_GPL(vhost_enable_notify); > static void vhost_disable_notify_packed(struct vhost_dev *dev, > struct vhost_virtqueue *vq) > { > - /* TODO: disable notification through device area */ > + __virtio16 flags; > + int r; > + > + if (vq->used_flags & VRING_USED_F_NO_NOTIFY) > + return; > + vq->used_flags |= VRING_USED_F_NO_NOTIFY; > + > + flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE); > + r = vhost_update_device_flags(vq, flags); > + if (r) > + vq_err(vq, "Failed to enable notification at %p: %d\n", > + &vq->device_event->flags, r); > } > > static void vhost_disable_notify_split(struct vhost_dev *dev, > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index db09958..d071daf 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -96,8 +96,14 @@ struct vhost_virtqueue { > struct vring_desc __user *desc; > struct vring_desc_packed __user *desc_packed; > }; > - struct vring_avail __user *avail; > - struct vring_used __user *used; > + union { > + struct vring_avail __user *avail; > + struct vring_packed_desc_event __user *driver_event; > + }; > + union { > + struct vring_used __user *used; > + struct vring_packed_desc_event __user *device_event; > + }; > const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS]; > struct file *kick; > struct eventfd_ctx *call_ctx; > -- > 2.7.4 >
On 2018年07月04日 12:13, Wei Xu wrote: > On Tue, Jul 03, 2018 at 01:38:04PM +0800, Jason Wang wrote: >> This patch introduces support for event suppression. This is done by >> have a two areas: device area and driver area. One side could then try >> to disable or enable (delayed) notification from other side by using a >> boolean hint or event index interface in the areas. >> >> For more information, please refer Virtio spec. >> >> Signed-off-by: Jason Wang<jasowang@redhat.com> >> --- >> drivers/vhost/vhost.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++---- >> drivers/vhost/vhost.h | 10 ++- >> 2 files changed, 185 insertions(+), 16 deletions(-) >> >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >> index 0f3f07c..cccbc82 100644 >> --- a/drivers/vhost/vhost.c >> +++ b/drivers/vhost/vhost.c >> @@ -1115,10 +1115,15 @@ static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num, >> struct vring_used __user *used) >> { >> struct vring_desc_packed *packed = (struct vring_desc_packed *)desc; >> + struct vring_packed_desc_event *driver_event = >> + (struct vring_packed_desc_event *)avail; >> + struct vring_packed_desc_event *device_event = >> + (struct vring_packed_desc_event *)used; >> >> - /* TODO: check device area and driver area */ >> return access_ok(VERIFY_READ, packed, num * sizeof(*packed)) && >> - access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)); >> + access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)) && > R/W parameter doesn't make sense to most architectures and the comment in x86 > says WRITE is a superset of READ, is it possible to converge them here? > > /** > * access_ok: - Checks if a user space pointer is valid > * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that > * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe > * to write to a block, it is always safe to read from it. > * @addr: User space pointer to start of block to check > * @size: Size of block to check > * > * Context: User context only. This function may sleep if pagefaults are > * enabled. > * > * Checks if a pointer to a block of memory in user space is valid. > * > * Returns true (nonzero) if the memory block may be valid, false (zero) > * if it is definitely invalid. > * > * Note that, depending on architecture, this function probably just > * checks that the pointer is in the user space range - after calling > * this function, memory access functions may still return -EFAULT. > */ > #define access_ok(type, addr, size) > ...... > > Thanks, > Wei > Well, this is a question that beyond the scope of this patch. My understanding is we should keep it unless type was meaningless on all archs. Thanks
On Wed, Jul 04, 2018 at 01:23:18PM +0800, Jason Wang wrote: > > > On 2018年07月04日 12:13, Wei Xu wrote: > >On Tue, Jul 03, 2018 at 01:38:04PM +0800, Jason Wang wrote: > >>This patch introduces support for event suppression. This is done by > >>have a two areas: device area and driver area. One side could then try > >>to disable or enable (delayed) notification from other side by using a > >>boolean hint or event index interface in the areas. > >> > >>For more information, please refer Virtio spec. > >> > >>Signed-off-by: Jason Wang<jasowang@redhat.com> > >>--- > >> drivers/vhost/vhost.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++---- > >> drivers/vhost/vhost.h | 10 ++- > >> 2 files changed, 185 insertions(+), 16 deletions(-) > >> > >>diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > >>index 0f3f07c..cccbc82 100644 > >>--- a/drivers/vhost/vhost.c > >>+++ b/drivers/vhost/vhost.c > >>@@ -1115,10 +1115,15 @@ static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num, > >> struct vring_used __user *used) > >> { > >> struct vring_desc_packed *packed = (struct vring_desc_packed *)desc; > >>+ struct vring_packed_desc_event *driver_event = > >>+ (struct vring_packed_desc_event *)avail; > >>+ struct vring_packed_desc_event *device_event = > >>+ (struct vring_packed_desc_event *)used; > >>- /* TODO: check device area and driver area */ > >> return access_ok(VERIFY_READ, packed, num * sizeof(*packed)) && > >>- access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)); > >>+ access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)) && > >R/W parameter doesn't make sense to most architectures and the comment in x86 > >says WRITE is a superset of READ, is it possible to converge them here? > > > >/** > > * access_ok: - Checks if a user space pointer is valid > > * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that > > * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe > > * to write to a block, it is always safe to read from it. > > * @addr: User space pointer to start of block to check > > * @size: Size of block to check > > * > > * Context: User context only. This function may sleep if pagefaults are > > * enabled. > > * > > * Checks if a pointer to a block of memory in user space is valid. > > * > > * Returns true (nonzero) if the memory block may be valid, false (zero) > > * if it is definitely invalid. > > * > > * Note that, depending on architecture, this function probably just > > * checks that the pointer is in the user space range - after calling > > * this function, memory access functions may still return -EFAULT. > > */ > >#define access_ok(type, addr, size) > >...... > > > >Thanks, > >Wei > > > > Well, this is a question that beyond the scope of this patch. > > My understanding is we should keep it unless type was meaningless on all > archs. No problem, go ahead. Wei > > Thanks >
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 0f3f07c..cccbc82 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1115,10 +1115,15 @@ static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num, struct vring_used __user *used) { struct vring_desc_packed *packed = (struct vring_desc_packed *)desc; + struct vring_packed_desc_event *driver_event = + (struct vring_packed_desc_event *)avail; + struct vring_packed_desc_event *device_event = + (struct vring_packed_desc_event *)used; - /* TODO: check device area and driver area */ return access_ok(VERIFY_READ, packed, num * sizeof(*packed)) && - access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)); + access_ok(VERIFY_WRITE, packed, num * sizeof(*packed)) && + access_ok(VERIFY_READ, driver_event, sizeof(*driver_event)) && + access_ok(VERIFY_WRITE, device_event, sizeof(*device_event)); } static int vq_access_ok_split(struct vhost_virtqueue *vq, unsigned int num, @@ -1193,14 +1198,27 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq, return true; } -int vq_iotlb_prefetch(struct vhost_virtqueue *vq) +int vq_iotlb_prefetch_packed(struct vhost_virtqueue *vq) +{ + int num = vq->num; + + return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc, + num * sizeof(*vq->desc), VHOST_ADDR_DESC) && + iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->desc, + num * sizeof(*vq->desc), VHOST_ADDR_DESC) && + iotlb_access_ok(vq, VHOST_ACCESS_RO, + (u64)(uintptr_t)vq->driver_event, + sizeof(*vq->driver_event), VHOST_ADDR_AVAIL) && + iotlb_access_ok(vq, VHOST_ACCESS_WO, + (u64)(uintptr_t)vq->device_event, + sizeof(*vq->device_event), VHOST_ADDR_USED); +} + +int vq_iotlb_prefetch_split(struct vhost_virtqueue *vq) { size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; unsigned int num = vq->num; - if (!vq->iotlb) - return 1; - return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc, num * sizeof(*vq->desc), VHOST_ADDR_DESC) && iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail, @@ -1212,6 +1230,17 @@ int vq_iotlb_prefetch(struct vhost_virtqueue *vq) num * sizeof(*vq->used->ring) + s, VHOST_ADDR_USED); } + +int vq_iotlb_prefetch(struct vhost_virtqueue *vq) +{ + if (!vq->iotlb) + return 1; + + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) + return vq_iotlb_prefetch_packed(vq); + else + return vq_iotlb_prefetch_split(vq); +} EXPORT_SYMBOL_GPL(vq_iotlb_prefetch); /* Can we log writes? */ @@ -1771,6 +1800,50 @@ static int vhost_update_used_flags(struct vhost_virtqueue *vq) return 0; } +static int vhost_update_device_flags(struct vhost_virtqueue *vq, + __virtio16 device_flags) +{ + void __user *flags; + + if (vhost_put_user(vq, device_flags, &vq->device_event->flags, + VHOST_ADDR_USED) < 0) + return -EFAULT; + if (unlikely(vq->log_used)) { + /* Make sure the flag is seen before log. */ + smp_wmb(); + /* Log used flag write. */ + flags = &vq->device_event->flags; + log_write(vq->log_base, vq->log_addr + + (flags - (void __user *)vq->device_event), + sizeof(vq->device_event->flags)); + if (vq->log_ctx) + eventfd_signal(vq->log_ctx, 1); + } + return 0; +} + +static int vhost_update_device_off_wrap(struct vhost_virtqueue *vq, + __virtio16 device_off_wrap) +{ + void __user *off_wrap; + + if (vhost_put_user(vq, device_off_wrap, &vq->device_event->off_wrap, + VHOST_ADDR_USED) < 0) + return -EFAULT; + if (unlikely(vq->log_used)) { + /* Make sure the flag is seen before log. */ + smp_wmb(); + /* Log used flag write. */ + off_wrap = &vq->device_event->off_wrap; + log_write(vq->log_base, vq->log_addr + + (off_wrap - (void __user *)vq->device_event), + sizeof(vq->device_event->off_wrap)); + if (vq->log_ctx) + eventfd_signal(vq->log_ctx, 1); + } + return 0; +} + static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) { if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx), @@ -2756,16 +2829,13 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, } EXPORT_SYMBOL_GPL(vhost_add_used_n); -static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) +static bool vhost_notify_split(struct vhost_dev *dev, + struct vhost_virtqueue *vq) { __u16 old, new; __virtio16 event; bool v; - /* TODO: check driver area */ - if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) - return true; - /* Flush out used index updates. This is paired * with the barrier that the Guest executes when enabling * interrupts. */ @@ -2798,6 +2868,64 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) return vring_need_event(vhost16_to_cpu(vq, event), new, old); } +static bool vhost_notify_packed(struct vhost_dev *dev, + struct vhost_virtqueue *vq) +{ + __virtio16 event_off_wrap, event_flags; + __u16 old, new, off_wrap; + bool v; + + /* Flush out used descriptors updates. This is paired + * with the barrier that the Guest executes when enabling + * interrupts. + */ + smp_mb(); + + if (vhost_get_avail(vq, event_flags, + &vq->driver_event->flags) < 0) { + vq_err(vq, "Failed to get driver desc_event_flags"); + return true; + } + + if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) + return event_flags != + cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE); + + old = vq->signalled_used; + v = vq->signalled_used_valid; + new = vq->signalled_used = vq->last_used_idx; + vq->signalled_used_valid = true; + + if (event_flags != cpu_to_vhost16(vq, RING_EVENT_FLAGS_DESC)) + return event_flags != + cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE); + + /* Read desc event flags before event_off and event_wrap */ + smp_rmb(); + + if (vhost_get_avail(vq, event_off_wrap, + &vq->driver_event->off_wrap) < 0) { + vq_err(vq, "Failed to get driver desc_event_off/wrap"); + return true; + } + + off_wrap = vhost16_to_cpu(vq, event_off_wrap); + + if (unlikely(!v)) + return true; + + return vhost_vring_packed_need_event(vq, vq->last_used_wrap_counter, + off_wrap, new, old); +} + +static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) +{ + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) + return vhost_notify_packed(dev, vq); + else + return vhost_notify_split(dev, vq); +} + /* This actually signals the guest, using eventfd. */ void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) { @@ -2875,10 +3003,34 @@ static bool vhost_enable_notify_packed(struct vhost_dev *dev, struct vhost_virtqueue *vq) { struct vring_desc_packed *d = vq->desc_packed + vq->avail_idx; - __virtio16 flags; + __virtio16 flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_ENABLE); int ret; - /* TODO: enable notification through device area */ + if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) + return false; + vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; + + if (vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { + __virtio16 off_wrap = cpu_to_vhost16(vq, vq->avail_idx | + vq->avail_wrap_counter << 15); + + ret = vhost_update_device_off_wrap(vq, off_wrap); + if (ret) { + vq_err(vq, "Failed to write to off warp at %p: %d\n", + &vq->device_event->off_wrap, ret); + return false; + } + /* Make sure off_wrap is wrote before flags */ + smp_wmb(); + flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_DESC); + } + + ret = vhost_update_device_flags(vq, flags); + if (ret) { + vq_err(vq, "Failed to enable notification at %p: %d\n", + &vq->device_event->flags, ret); + return false; + } /* They could have slipped one in as we were doing that: make * sure it's written, then check again. @@ -2945,7 +3097,18 @@ EXPORT_SYMBOL_GPL(vhost_enable_notify); static void vhost_disable_notify_packed(struct vhost_dev *dev, struct vhost_virtqueue *vq) { - /* TODO: disable notification through device area */ + __virtio16 flags; + int r; + + if (vq->used_flags & VRING_USED_F_NO_NOTIFY) + return; + vq->used_flags |= VRING_USED_F_NO_NOTIFY; + + flags = cpu_to_vhost16(vq, RING_EVENT_FLAGS_DISABLE); + r = vhost_update_device_flags(vq, flags); + if (r) + vq_err(vq, "Failed to enable notification at %p: %d\n", + &vq->device_event->flags, r); } static void vhost_disable_notify_split(struct vhost_dev *dev, diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index db09958..d071daf 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -96,8 +96,14 @@ struct vhost_virtqueue { struct vring_desc __user *desc; struct vring_desc_packed __user *desc_packed; }; - struct vring_avail __user *avail; - struct vring_used __user *used; + union { + struct vring_avail __user *avail; + struct vring_packed_desc_event __user *driver_event; + }; + union { + struct vring_used __user *used; + struct vring_packed_desc_event __user *device_event; + }; const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS]; struct file *kick; struct eventfd_ctx *call_ctx;
This patch introduces support for event suppression. This is done by have a two areas: device area and driver area. One side could then try to disable or enable (delayed) notification from other side by using a boolean hint or event index interface in the areas. For more information, please refer Virtio spec. Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/vhost.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++---- drivers/vhost/vhost.h | 10 ++- 2 files changed, 185 insertions(+), 16 deletions(-)