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Message-Id: <20190717105255.63488-15-jasowang@redhat.com>
Date: Wed, 17 Jul 2019 06:52:54 -0400
From: Jason Wang <jasowang@...hat.com>
To: mst@...hat.com, jasowang@...hat.com
Cc: kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
jfreimann@...hat.com, tiwei.bie@...el.com,
maxime.coquelin@...hat.com
Subject: [PATCH V3 14/15] vhost: event suppression for packed ring
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@...hat.com>
---
drivers/vhost/vhost.c | 265 +++++++++++++++++++++++++++++++++++++++---
drivers/vhost/vhost.h | 11 +-
2 files changed, 255 insertions(+), 21 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a7d24b9d5204..a188e9af3b35 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1524,6 +1524,76 @@ static inline int vhost_put_desc_flags(struct vhost_virtqueue *vq,
return vhost_put_user(vq, *flags, &desc->flags, VHOST_ADDR_DESC);
}
+static int vhost_get_driver_off_wrap(struct vhost_virtqueue *vq,
+ __virtio16 *off_wrap)
+{
+#if VHOST_ARCH_CAN_ACCEL_UACCESS
+ struct vring_packed_desc_event *event =
+ vhost_get_meta_ptr(vq, VHOST_ADDR_AVAIL);
+ if (likely(event)) {
+ *off_wrap = event->off_wrap;
+ vhost_put_meta_ptr();
+ return 0;
+ }
+#endif
+ return vhost_get_user(vq, *off_wrap,
+ &vq->driver_event->off_wrap,
+ VHOST_ADDR_AVAIL);
+}
+
+static int vhost_get_driver_flags(struct vhost_virtqueue *vq,
+ __virtio16 *driver_flags)
+{
+#if VHOST_ARCH_CAN_ACCEL_UACCESS
+ struct vring_packed_desc_event *event =
+ vhost_get_meta_ptr(vq, VHOST_ADDR_AVAIL);
+
+ if (likely(event)) {
+ *driver_flags = event->flags;
+ vhost_put_meta_ptr();
+ return 0;
+ }
+#endif
+ return vhost_get_user(vq, *driver_flags, &vq->driver_event->flags,
+ VHOST_ADDR_AVAIL);
+}
+
+static int vhost_put_device_off_wrap(struct vhost_virtqueue *vq,
+ __virtio16 *off_wrap)
+{
+#if VHOST_ARCH_CAN_ACCEL_UACCESS
+ struct vring_packed_desc_event *event =
+ vhost_get_meta_ptr(vq, VHOST_ADDR_USED);
+
+ if (likely(event)) {
+ event->off_wrap = *off_wrap;
+ vhost_put_meta_ptr();
+ return 0;
+ }
+#endif
+ return vhost_put_user(vq, *off_wrap,
+ &vq->device_event->off_wrap,
+ VHOST_ADDR_USED);
+}
+
+static int vhost_put_device_flags(struct vhost_virtqueue *vq,
+ __virtio16 *device_flags)
+{
+#if VHOST_ARCH_CAN_ACCEL_UACCESS
+ struct vring_packed_desc_event *event =
+ vhost_get_meta_ptr(vq, VHOST_ADDR_USED);
+
+ if (likely(event)) {
+ event->flags = *device_flags;
+ vhost_put_meta_ptr();
+ return 0;
+ }
+#endif
+ return vhost_put_user(vq, *device_flags,
+ &vq->device_event->flags,
+ VHOST_ADDR_USED);
+}
+
static int vhost_new_umem_range(struct vhost_umem *umem,
u64 start, u64 size, u64 end,
u64 userspace_addr, int perm)
@@ -1809,10 +1879,15 @@ static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num,
struct vring_used __user *used)
{
struct vring_packed_desc *packed = (struct vring_packed_desc *)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(packed, num * sizeof(*packed)) &&
- access_ok(packed, num * sizeof(*packed));
+ access_ok(packed, num * sizeof(*packed)) &&
+ access_ok(driver_event, sizeof(*driver_event)) &&
+ access_ok(device_event, sizeof(*device_event));
}
static int vq_access_ok_split(struct vhost_virtqueue *vq, unsigned int num,
@@ -1904,16 +1979,25 @@ static void vhost_vq_map_prefetch(struct vhost_virtqueue *vq)
}
#endif
-int vq_meta_prefetch(struct vhost_virtqueue *vq)
+static int vq_iotlb_prefetch_packed(struct vhost_virtqueue *vq)
{
- unsigned int num = vq->num;
+ int num = vq->num;
- if (!vq->iotlb) {
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
- vhost_vq_map_prefetch(vq);
-#endif
- 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_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);
+}
+
+static int vq_iotlb_prefetch_split(struct vhost_virtqueue *vq)
+{
+ unsigned int num = vq->num;
return iotlb_access_ok(vq, VHOST_ACCESS_RO,
(u64)(uintptr_t)vq->desc,
@@ -1928,6 +2012,21 @@ int vq_meta_prefetch(struct vhost_virtqueue *vq)
vhost_get_used_size(vq, num),
VHOST_ADDR_USED);
}
+
+int vq_meta_prefetch(struct vhost_virtqueue *vq)
+{
+ if (!vq->iotlb) {
+#if VHOST_ARCH_CAN_ACCEL_UACCESS
+ vhost_vq_map_prefetch(vq);
+#endif
+ 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_meta_prefetch);
/* Can we log writes? */
@@ -2620,6 +2719,48 @@ 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_device_flags(vq, &device_flags))
+ 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_device_off_wrap(vq, &device_off_wrap))
+ 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_avail_event(vq))
@@ -3689,16 +3830,13 @@ int vhost_add_used(struct vhost_virtqueue *vq, struct vhost_used_elem *used,
}
EXPORT_SYMBOL_GPL(vhost_add_used);
-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. */
@@ -3731,6 +3869,62 @@ 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_driver_flags(vq, &event_flags)) {
+ 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, VRING_PACKED_EVENT_FLAG_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, VRING_PACKED_EVENT_FLAG_DESC))
+ return event_flags !=
+ cpu_to_vhost16(vq, VRING_PACKED_EVENT_FLAG_DISABLE);
+
+ /* Read desc event flags before event_off and event_wrap */
+ smp_rmb();
+
+ if (vhost_get_driver_off_wrap(vq, &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)
{
@@ -3836,10 +4030,34 @@ EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
static bool vhost_enable_notify_packed(struct vhost_virtqueue *vq)
{
struct vring_packed_desc *d = vq->desc_packed + vq->avail_idx;
- __virtio16 flags;
+ __virtio16 flags = cpu_to_vhost16(vq, VRING_PACKED_EVENT_FLAG_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, VRING_PACKED_EVENT_FLAG_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.
@@ -3901,7 +4119,18 @@ EXPORT_SYMBOL_GPL(vhost_enable_notify);
static void vhost_disable_notify_packed(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, VRING_PACKED_EVENT_FLAG_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_virtqueue *vq)
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 7f3a2dd1b628..bb3f8bb763b9 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -125,9 +125,14 @@ struct vhost_virtqueue {
struct vring_desc __user *desc;
struct vring_packed_desc __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;
+ };
#if VHOST_ARCH_CAN_ACCEL_UACCESS
/* Read by memory accessors, modified by meta data
* prefetching, MMU notifier and vring ioctl().
--
2.18.1
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