On Mon, Sep 10, 2018 at 10:13:22AM +0800, Tiwei Bie wrote:

On Fri, Sep 07, 2018 at 09:51:23AM -0400, Michael S. Tsirkin wrote:

quoted

On Wed, Jul 11, 2018 at 10:27:07AM +0800, Tiwei Bie wrote:

quoted

Signed-off-by: Tiwei Bie <redacted>
---
 include/uapi/linux/virtio_config.h |  3 +++
 include/uapi/linux/virtio_ring.h   | 43 ++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
index 449132c76b1c..1196e1c1d4f6 100644
--- a/include/uapi/linux/virtio_config.h
+++ b/include/uapi/linux/virtio_config.h

@@ -75,6 +75,9 @@
  */
 #define VIRTIO_F_IOMMU_PLATFORM		33
 
+/* This feature indicates support for the packed virtqueue layout. */
+#define VIRTIO_F_RING_PACKED		34
+
 /*
  * Does the device support Single Root I/O Virtualization?
  */

diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h
index 6d5d5faa989b..0254a2ba29cf 100644
--- a/include/uapi/linux/virtio_ring.h
+++ b/include/uapi/linux/virtio_ring.h

@@ -44,6 +44,10 @@
 /* This means the buffer contains a list of buffer descriptors. */
 #define VRING_DESC_F_INDIRECT	4
 
+/* Mark a descriptor as available or used. */
+#define VRING_DESC_F_AVAIL	(1ul << 7)
+#define VRING_DESC_F_USED	(1ul << 15)
+
 /* The Host uses this in used->flags to advise the Guest: don't kick me when
  * you add a buffer.  It's unreliable, so it's simply an optimization.  Guest
  * will still kick if it's out of buffers. */

@@ -53,6 +57,17 @@
  * optimization.  */
 #define VRING_AVAIL_F_NO_INTERRUPT	1
 
+/* Enable events. */
+#define VRING_EVENT_F_ENABLE	0x0
+/* Disable events. */
+#define VRING_EVENT_F_DISABLE	0x1
+/*
+ * Enable events for a specific descriptor
+ * (as specified by Descriptor Ring Change Event Offset/Wrap Counter).
+ * Only valid if VIRTIO_RING_F_EVENT_IDX has been negotiated.
+ */
+#define VRING_EVENT_F_DESC	0x2
+
 /* We support indirect buffer descriptors */
 #define VIRTIO_RING_F_INDIRECT_DESC	28
 

These are for the packed ring, right? Pls prefix accordingly.

How about something like this:

#define VRING_PACKED_DESC_F_AVAIL	(1u << 7)
#define VRING_PACKED_DESC_F_USED	(1u << 15)

_F_ should be a bit number, not a shifted value.
Yes I know current virtio_ring.h is inconsistent in
that respect. changes welcome though we need to
maintain the old names for the sake of old apps.

#define VRING_PACKED_EVENT_F_ENABLE	0x0
#define VRING_PACKED_EVENT_F_DISABLE	0x1
#define VRING_PACKED_EVENT_F_DESC	0x2

These are values, I think they should not have _F_.
Yes I know current virtio_ring.h is inconsistent in
that respect.

quoted

Also, you likely need macros for the wrap counters.

How about something like this:

#define VRING_PACKED_EVENT_WRAP_COUNTER_SHIFT	15

Given it's a single bit, maybe even
VRING_PACKED_EVENT_F_WRAP_CTR

#define VRING_PACKED_EVENT_WRAP_COUNTER_MASK	\
			(1u << VRING_PACKED_WRAP_COUNTER_SHIFT)
#define VRING_PACKED_EVENT_OFFSET_MASK	\
			((1u << VRING_PACKED_WRAP_COUNTER_SHIFT) - 1)

I'm not sure the mask is justified.

quoted

quoted

@@ -171,4 +186,32 @@ static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old)
 	return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);
 }
 
+struct vring_packed_desc_event {
+	/* Descriptor Ring Change Event Offset/Wrap Counter. */
+	__virtio16 off_wrap;
+	/* Descriptor Ring Change Event Flags. */
+	__virtio16 flags;
+};
+
+struct vring_packed_desc {
+	/* Buffer Address. */
+	__virtio64 addr;
+	/* Buffer Length. */
+	__virtio32 len;
+	/* Buffer ID. */
+	__virtio16 id;
+	/* The flags depending on descriptor type. */
+	__virtio16 flags;
+};

Don't use __virtioXX types, just __leXX ones.

Got it, will do that.

quoted

quoted

+
+struct vring_packed {
+	unsigned int num;
+
+	struct vring_packed_desc *desc;
+
+	struct vring_packed_desc_event *driver;
+
+	struct vring_packed_desc_event *device;
+};
+
 #endif /* _UAPI_LINUX_VIRTIO_RING_H */
-- 
2.18.0