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virtio: support VIRTIO_F_IO_BARRIER

PATCH In review Tiwei Bie 2 participants 7 messages May 4, 2018 – May 10, 2018 virtio core

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Tiwei Bie

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#0 lore raw

PATCH 1/1 virtio: support VIRTIO_F_IO_BARRIER

This patch introduces the support for VIRTIO_F_IO_BARRIER. When this feature is negotiated, driver will use the barriers suitable for hardware devices.

Signed-off-by Tiwei Bie <[email protected]>

---
This patch depends on below proposal for virtio-spec:
https://lists.oasis-open.org/archives/virtio-dev/201805/msg00019.html

This patch also depends on below patch:
https://lkml.org/lkml/2018/4/19/789

RFC -> v1:
- Address the changes in the proposal;

 drivers/virtio/virtio_ring.c       | 5 +++++
 include/uapi/linux/virtio_config.h | 8 +++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)
drivers/virtio/virtio_ring.c +5 -0
index 21d464a29cf8..edb565643bf4 100644
@@ -996,6 +996,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 		!context;
 	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
 
+	if (virtio_has_feature(vdev, VIRTIO_F_IO_BARRIER))
+		vq->weak_barriers = false;
+
 	/* No callback?  Tell other side not to bother us. */
 	if (!callback) {
 		vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;

@@ -1164,6 +1167,8 @@ void vring_transport_features(struct virtio_device *vdev)
 			break;
 		case VIRTIO_F_IOMMU_PLATFORM:
 			break;
+		case VIRTIO_F_IO_BARRIER:
+			break;
 		default:
 			/* We don't understand this bit. */
 			__virtio_clear_bit(vdev, i);
include/uapi/linux/virtio_config.h +7 -1
index 308e2096291f..9fb519a9df28 100644
@@ -49,7 +49,7 @@
  * transport being used (eg. virtio_ring), the rest are per-device feature
  * bits. */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		34
+#define VIRTIO_TRANSPORT_F_END		37
 
 #ifndef VIRTIO_CONFIG_NO_LEGACY
 /* Do we get callbacks when the ring is completely used, even if we've

@@ -71,4 +71,10 @@
  * this is for compatibility with legacy systems.
  */
 #define VIRTIO_F_IOMMU_PLATFORM		33
+
+/*
+ * If clear - driver may use barriers suitable for CPU cores.
+ * If set - driver must use barriers suitable for hardware devices.
+ */
+#define VIRTIO_F_IO_BARRIER		36
 #endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
Signature · 1 line
2.11.0
#1 lore raw

include/uapi/linux/virtio_config.h line 52

Quoted 10 lines · Tiwei Bie
include/uapi/linux/virtio_config.h +1 -1
index 308e2096291f..9fb519a9df28 100644
@@ -49,7 +49,7 @@
  * transport being used (eg. virtio_ring), the rest are per-device feature
  * bits. */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		34
+#define VIRTIO_TRANSPORT_F_END		37

Have you updated "2.2 Feature Bits" in the VIRTIO spec?

In 1.0 it says:

24 to 32
Feature bits reserved for extensions to the queue and feature negotiation mechanisms

This information is out-of-date.

Stefan

_______________________________________________
Virtualization mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

author
#2 lore raw
Quoted 14 lines · Stefan Hajnoczi

include/uapi/linux/virtio_config.h line 52

Quoted 10 lines · Tiwei Bie
include/uapi/linux/virtio_config.h +1 -1
index 308e2096291f..9fb519a9df28 100644
@@ -49,7 +49,7 @@
  * transport being used (eg. virtio_ring), the rest are per-device feature
  * bits. */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		34
+#define VIRTIO_TRANSPORT_F_END		37

Have you updated "2.2 Feature Bits" in the VIRTIO spec?

Quoted 7 lines

In 1.0 it says:

24 to 32
Feature bits reserved for extensions to the queue and feature negotiation mechanisms

This information is out-of-date.

No. In the latest spec draft, it's 24 to 33. And it becomes out-of-date since VIRTIO_F_RING_PACKED(34) and VIRTIO_F_IN_ORDER(35) were introduced. Do you want me to update it in the IO_BARRIER patch or do you want me to update it in a new patch?

Best regards,
Tiwei Bie

#3 lore raw
Quoted 20 lines · Tiwei Bie
Quoted 19 lines · Stefan Hajnoczi

include/uapi/linux/virtio_config.h line 52

Quoted 10 lines · Tiwei Bie
include/uapi/linux/virtio_config.h +1 -1
index 308e2096291f..9fb519a9df28 100644
@@ -49,7 +49,7 @@
  * transport being used (eg. virtio_ring), the rest are per-device feature
  * bits. */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		34
+#define VIRTIO_TRANSPORT_F_END		37

Have you updated "2.2 Feature Bits" in the VIRTIO spec?

In 1.0 it says:

24 to 32
Feature bits reserved for extensions to the queue and feature negotiation mechanisms

Quoted 8 lines
Quoted 2 lines

This information is out-of-date.

No. In the latest spec draft, it's 24 to 33. And it becomes out-of-date since VIRTIO_F_RING_PACKED(34) and VIRTIO_F_IN_ORDER(35) were introduced. Do you want me to update it in the IO_BARRIER patch or do you want me to update it in a new patch?

Please update it to 37 in the IO_BARRIER patch.

Stefan

_______________________________________________
Virtualization mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

#4 lore raw
In reply to Tiwei Bie
Quoted 20 lines · Tiwei Bie
Quoted 19 lines · Stefan Hajnoczi

include/uapi/linux/virtio_config.h line 52

Quoted 10 lines · Tiwei Bie
include/uapi/linux/virtio_config.h +1 -1
index 308e2096291f..9fb519a9df28 100644
@@ -49,7 +49,7 @@
  * transport being used (eg. virtio_ring), the rest are per-device feature
  * bits. */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		34
+#define VIRTIO_TRANSPORT_F_END		37

Have you updated "2.2 Feature Bits" in the VIRTIO spec?

In 1.0 it says:

24 to 32
Feature bits reserved for extensions to the queue and feature negotiation mechanisms

Quoted 8 lines
Quoted 2 lines

This information is out-of-date.

No. In the latest spec draft, it's 24 to 33. And it becomes out-of-date since VIRTIO_F_RING_PACKED(34) and VIRTIO_F_IN_ORDER(35) were introduced. Do you want me to update it in the IO_BARRIER patch or do you want me to update it in a new patch?

Please update it to 37 in the IO_BARRIER patch.

Stefan

author
#5 lore raw
Quoted 24 lines · Stefan Hajnoczi
Quoted 23 lines · Tiwei Bie
Quoted 21 lines · Stefan Hajnoczi

include/uapi/linux/virtio_config.h line 52

Quoted 10 lines · Tiwei Bie
include/uapi/linux/virtio_config.h +1 -1
index 308e2096291f..9fb519a9df28 100644
@@ -49,7 +49,7 @@
  * transport being used (eg. virtio_ring), the rest are per-device feature
  * bits. */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		34
+#define VIRTIO_TRANSPORT_F_END		37

Have you updated "2.2 Feature Bits" in the VIRTIO spec?

In 1.0 it says:

24 to 32
Feature bits reserved for extensions to the queue and feature negotiation mechanisms

This information is out-of-date.

Quoted 7 lines
Quoted 5 lines

No. In the latest spec draft, it's 24 to 33. And it becomes out-of-date since VIRTIO_F_RING_PACKED(34) and VIRTIO_F_IN_ORDER(35) were introduced. Do you want me to update it in the IO_BARRIER patch or do you want me to update it in a new patch?

Please update it to 37 in the IO_BARRIER patch.

Will do it! Thanks!

Best regards,
Tiwei Bie

author
#6 lore raw
In reply to Stefan Hajnoczi
Quoted 14 lines · Stefan Hajnoczi

include/uapi/linux/virtio_config.h line 52

Quoted 10 lines · Tiwei Bie
include/uapi/linux/virtio_config.h +1 -1
index 308e2096291f..9fb519a9df28 100644
@@ -49,7 +49,7 @@
  * transport being used (eg. virtio_ring), the rest are per-device feature
  * bits. */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		34
+#define VIRTIO_TRANSPORT_F_END		37

Have you updated "2.2 Feature Bits" in the VIRTIO spec?

Quoted 7 lines

In 1.0 it says:

24 to 32
Feature bits reserved for extensions to the queue and feature negotiation mechanisms

This information is out-of-date.

No. In the latest spec draft, it's 24 to 33. And it becomes out-of-date since VIRTIO_F_RING_PACKED(34) and VIRTIO_F_IN_ORDER(35) were introduced. Do you want me to update it in the IO_BARRIER patch or do you want me to update it in a new patch?

Best regards,
Tiwei Bie