Displaying 20 results from an estimated 206 matches for "virtio_mb".
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2011 Dec 21
0
[PATCH] virtio: harsher barriers for virtio-mmio.
...rivers/virtio/virtio_ring.c
@@ -28,17 +28,20 @@
#ifdef CONFIG_SMP
/* Where possible, use SMP barriers which are more lightweight than mandatory
* barriers, because mandatory barriers control MMIO effects on accesses
- * through relaxed memory I/O windows (which virtio does not use). */
-#define virtio_mb() smp_mb()
-#define virtio_rmb() smp_rmb()
-#define virtio_wmb() smp_wmb()
+ * through relaxed memory I/O windows (which virtio-pci does not use). */
+#define virtio_mb(vq) \
+ do { if ((vq)->weak_barriers) smp_mb(); else mb(); } while(0)
+#define virtio_rmb(vq) \
+ do { if ((vq)->weak_barrie...
2011 Dec 21
0
[PATCH] virtio: harsher barriers for virtio-mmio.
...rivers/virtio/virtio_ring.c
@@ -28,17 +28,20 @@
#ifdef CONFIG_SMP
/* Where possible, use SMP barriers which are more lightweight than mandatory
* barriers, because mandatory barriers control MMIO effects on accesses
- * through relaxed memory I/O windows (which virtio does not use). */
-#define virtio_mb() smp_mb()
-#define virtio_rmb() smp_rmb()
-#define virtio_wmb() smp_wmb()
+ * through relaxed memory I/O windows (which virtio-pci does not use). */
+#define virtio_mb(vq) \
+ do { if ((vq)->weak_barriers) smp_mb(); else mb(); } while(0)
+#define virtio_rmb(vq) \
+ do { if ((vq)->weak_barrie...
2011 Nov 29
4
[RFC] virtio: use mandatory barriers for remote processor vdevs
...d be used by virtio devices that run on remote
processors. The CONFIG_SMP variant of virtio_{mb, rmb, wmb} is then changed
to use SMP barriers only if VIRTIO_RING_F_REMOTEPROC was absent.
Signed-off-by: Ohad Ben-Cohen <ohad at wizery.com>
---
Alternatively, we can also introduce some kind of virtio_mb_ops and set it
according to the nature of the vdev with handlers that just do the right
thing, instead of introducting that branch.
Though I also wonder how big really is the perforamnce gain of d57ed95 ?
drivers/virtio/virtio_ring.c | 78 +++++++++++++++++++++++++++++-------------
include/lin...
2011 Nov 29
4
[RFC] virtio: use mandatory barriers for remote processor vdevs
...d be used by virtio devices that run on remote
processors. The CONFIG_SMP variant of virtio_{mb, rmb, wmb} is then changed
to use SMP barriers only if VIRTIO_RING_F_REMOTEPROC was absent.
Signed-off-by: Ohad Ben-Cohen <ohad at wizery.com>
---
Alternatively, we can also introduce some kind of virtio_mb_ops and set it
according to the nature of the vdev with handlers that just do the right
thing, instead of introducting that branch.
Though I also wonder how big really is the perforamnce gain of d57ed95 ?
drivers/virtio/virtio_ring.c | 78 +++++++++++++++++++++++++++++-------------
include/lin...
2015 Dec 17
2
[PATCH] virtio_ring: use smp_store_mb
...t; > + __virtio16 *p, __virtio16 v)
> > +{
> > +#ifdef CONFIG_SMP
> > + if (weak_barriers)
> > + smp_store_mb(*p, v);
> > + else
> > +#endif
> > + {
> > + WRITE_ONCE(*p, v);
> > + mb();
> > + }
> > +}
>
> Note that virtio_mb() is weirdly inconsistent with virtio_[rw]mb() in
> that they use dma_* ops for weak_barriers, while virtio_mb() uses
> smp_mb().
It's a hack really. I think I'll clean it up a bit to
make it more consistent.
To simplify things, you may consider things before
the optimization brough...
2015 Dec 17
2
[PATCH] virtio_ring: use smp_store_mb
...t; > + __virtio16 *p, __virtio16 v)
> > +{
> > +#ifdef CONFIG_SMP
> > + if (weak_barriers)
> > + smp_store_mb(*p, v);
> > + else
> > +#endif
> > + {
> > + WRITE_ONCE(*p, v);
> > + mb();
> > + }
> > +}
>
> Note that virtio_mb() is weirdly inconsistent with virtio_[rw]mb() in
> that they use dma_* ops for weak_barriers, while virtio_mb() uses
> smp_mb().
It's a hack really. I think I'll clean it up a bit to
make it more consistent.
To simplify things, you may consider things before
the optimization brough...
2010 Jan 27
1
[PATCHv2] virtio: use smp_XX barriers on SMP
...ry barriers are used to control SMP effects. */
+#ifdef CONFIG_SMP
+/* Where possible, use SMP barriers which are more lightweight than mandatory
+ * barriers, because mandatory barriers control MMIO effects on accesses
+ * through relaxed memory I/O windows (which virtio does not use). */
+#define virtio_mb() smp_mb()
+#define virtio_rmb() smp_rmb()
+#define virtio_wmb() smp_wmb()
+#else
+/* We must force memory ordering even if guest is UP since host could be
+ * running on another CPU, but SMP barriers are defined to barrier() in that
+ * configuration. So fall back to mandatory barriers instead. */...
2010 Jan 27
1
[PATCHv2] virtio: use smp_XX barriers on SMP
...ry barriers are used to control SMP effects. */
+#ifdef CONFIG_SMP
+/* Where possible, use SMP barriers which are more lightweight than mandatory
+ * barriers, because mandatory barriers control MMIO effects on accesses
+ * through relaxed memory I/O windows (which virtio does not use). */
+#define virtio_mb() smp_mb()
+#define virtio_rmb() smp_rmb()
+#define virtio_wmb() smp_wmb()
+#else
+/* We must force memory ordering even if guest is UP since host could be
+ * running on another CPU, but SMP barriers are defined to barrier() in that
+ * configuration. So fall back to mandatory barriers instead. */...
2015 Dec 17
4
[PATCH] virtio_ring: use smp_store_mb
...for the next entry, tell host
* by writing event index and flush out the write before
* the read in the next get_buf call. */
- if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
- vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, vq->last_used_idx);
- virtio_mb(vq->weak_barriers);
- }
+ if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+ virtio_store_mb(vq->weak_barriers,
+ &vring_used_event(&vq->vring),
+ cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
#ifdef DEBUG
vq->last_add_time_valid = false;
@@...
2015 Dec 17
4
[PATCH] virtio_ring: use smp_store_mb
...for the next entry, tell host
* by writing event index and flush out the write before
* the read in the next get_buf call. */
- if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
- vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, vq->last_used_idx);
- virtio_mb(vq->weak_barriers);
- }
+ if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+ virtio_store_mb(vq->weak_barriers,
+ &vring_used_event(&vq->vring),
+ cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
#ifdef DEBUG
vq->last_add_time_valid = false;
@@...
2018 Sep 07
1
[PATCH net-next v2 4/5] virtio_ring: add event idx support in packed ring
...ruct vring_virtqueue *vq = to_vvq(_vq);
> - u16 flags;
> + u16 new, old, off_wrap, flags, wrap_counter, event_idx;
> bool needs_kick;
> u32 snapshot;
>
> @@ -1059,9 +1059,19 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
> * suppressions. */
> virtio_mb(vq->weak_barriers);
>
> + old = vq->next_avail_idx - vq->num_added;
> + new = vq->next_avail_idx;
> + vq->num_added = 0;
> +
> snapshot = READ_ONCE(*(u32 *)vq->vring_packed.device);
> + off_wrap = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot & 0...
2012 Jan 20
3
[PATCH 1/2] virtio: fix typos of memory barriers
Signed-off-by: Jason Wang <jasowang at redhat.com>
---
drivers/virtio/virtio_ring.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 79e1b29..78428a8 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -35,7 +35,7 @@
#define virtio_rmb(vq) \
do { if
2012 Jan 20
3
[PATCH 1/2] virtio: fix typos of memory barriers
Signed-off-by: Jason Wang <jasowang at redhat.com>
---
drivers/virtio/virtio_ring.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 79e1b29..78428a8 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -35,7 +35,7 @@
#define virtio_rmb(vq) \
do { if
2018 Jun 07
1
[RFC v6 4/5] virtio_ring: add event idx support in packed ring
...t;event ? VRING_EVENT_F_DESC :
> + VRING_EVENT_F_ENABLE;
> vq->vring_packed.driver->flags = cpu_to_virtio16(_vq->vdev,
> vq->event_flags_shadow);
> - /* We need to enable interrupts first before re-checking
> - * for more used buffers. */
> - virtio_mb(vq->weak_barriers);
> }
>
> + /* We need to update event suppression structure first
> + * before re-checking for more used buffers. */
> + virtio_mb(vq->weak_barriers);
> +
> if (more_used_packed(vq)) {
> END_USE(vq);
> return false;
I think what...
2016 Jan 01
0
[PATCH v2 30/32] virtio_ring: update weak barriers to use __smp_xxx
...xed memory I/O windows, so smp_mb() et al are
+ * accesses through relaxed memory I/O windows, so virt_mb() et al are
* sufficient.
*
* For using virtio to talk to real devices (eg. other heterogeneous
@@ -21,11 +21,10 @@
* actually quite cheap.
*/
-#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers)
{
if (weak_barriers)
- smp_mb();
+ virt_mb();
else
mb();
}
@@ -33,7 +32,7 @@ static inline void virtio_mb(bool weak_barriers)
static inline void virtio_rmb(bool weak_barriers)
{
if (weak_barriers)
- smp_rmb();
+ virt_rmb();
else
rmb();
}
@@ -41,26 +40,10 @...
2013 Jul 08
4
[PATCH 2/2] virtio_net: fix race in RX VQ processing
...onize virtqueue_enable_cq wrt
virtqueue_add_buf. In particular, used event can move backwards,
causing us to lose interrupts.
In a debug build, this can trigger panic within START_USE.
Jason Wang reports that he can trigger the races artificially,
by adding udelay() in virtqueue_enable_cb() after virtio_mb().
However, we must call napi_complete to clear NAPI_STATE_SCHED before
polling the virtqueue for used buffers, otherwise napi_schedule_prep in
a callback will fail, causing us to lose RX events.
To fix, call virtqueue_enable_cb_prepare with NAPI_STATE_SCHED
set (under napi lock), later call virt...
2013 Jul 08
4
[PATCH 2/2] virtio_net: fix race in RX VQ processing
...onize virtqueue_enable_cq wrt
virtqueue_add_buf. In particular, used event can move backwards,
causing us to lose interrupts.
In a debug build, this can trigger panic within START_USE.
Jason Wang reports that he can trigger the races artificially,
by adding udelay() in virtqueue_enable_cb() after virtio_mb().
However, we must call napi_complete to clear NAPI_STATE_SCHED before
polling the virtqueue for used buffers, otherwise napi_schedule_prep in
a callback will fail, causing us to lose RX events.
To fix, call virtqueue_enable_cb_prepare with NAPI_STATE_SCHED
set (under napi lock), later call virt...
2015 Apr 08
3
[PATCH] virtio_ring: Update weak barriers to use dma_wmb/rmb
...ertions(+), 19 deletions(-)
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 67e06fe18c03..8e50888a6d59 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -21,19 +21,20 @@
* actually quite cheap.
*/
-#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers)
{
+#ifdef CONFIG_SMP
if (weak_barriers)
smp_mb();
else
+#endif
mb();
}
static inline void virtio_rmb(bool weak_barriers)
{
if (weak_barriers)
- smp_rmb();
+ dma_rmb();
else
rmb();
}
@@ -41,26 +42,10 @@ static inline void virtio_rmb(bool weak_barriers)...
2015 Apr 08
3
[PATCH] virtio_ring: Update weak barriers to use dma_wmb/rmb
...ertions(+), 19 deletions(-)
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 67e06fe18c03..8e50888a6d59 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -21,19 +21,20 @@
* actually quite cheap.
*/
-#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers)
{
+#ifdef CONFIG_SMP
if (weak_barriers)
smp_mb();
else
+#endif
mb();
}
static inline void virtio_rmb(bool weak_barriers)
{
if (weak_barriers)
- smp_rmb();
+ dma_rmb();
else
rmb();
}
@@ -41,26 +42,10 @@ static inline void virtio_rmb(bool weak_barriers)...
2018 Jul 09
0
[PATCH net-next v1 4/5] virtio_ring: add event idx support in packed ring
...re_packed(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
- u16 flags;
+ u16 new, old, off_wrap, flags, wrap_counter, event_idx;
bool needs_kick;
u32 snapshot;
@@ -1059,9 +1059,19 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
* suppressions. */
virtio_mb(vq->weak_barriers);
+ old = vq->next_avail_idx - vq->num_added;
+ new = vq->next_avail_idx;
+ vq->num_added = 0;
+
snapshot = *(u32 *)vq->vring_packed.device;
+ off_wrap = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot & 0xffff));
flags = virtio16_to_cpu(_vq->vde...