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[Qemu-devel] [PATCH] vhost-user: support cross-endianess negatiation
From: |
Felipe Franciosi |
Subject: |
[Qemu-devel] [PATCH] vhost-user: support cross-endianess negatiation |
Date: |
Wed, 14 Jun 2017 17:41:26 +0100 |
Currently, vhost-user does not implement any means for notifying the
backend about guest endianess. This commit introduces a new message
called VHOST_USER_SET_VRING_ENDIAN which is analogous to the ioctl()
called VHOST_SET_VRING_ENDIAN used for kernel vhost backends. Such
message is necessary for backends supporting legacy (pre-1.0) virtio
devices running in big-endian guests.
Signed-off-by: Felipe Franciosi <address@hidden>
Signed-off-by: Mike Cui <address@hidden>
---
docs/specs/vhost-user.txt | 14 ++++++++++++++
hw/virtio/vhost-user.c | 23 +++++++++++++++++++++--
2 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 481ab56..eafbed9 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -326,6 +326,7 @@ Protocol features
#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
#define VHOST_USER_PROTOCOL_F_MTU 4
#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
+#define VHOST_USER_PROTOCOL_F_CROSS_ENDIAN 6
Master message types
--------------------
@@ -580,6 +581,19 @@ Master message types
This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
has been successfully negotiated.
+ * VHOST_USER_SET_VRING_ENDIAN
+
+ Id: 22
+ Equivalent ioctl: VHOST_SET_VRING_ENDIAN
+ Master payload: vring state description
+
+ Set the endianess of a VQ for legacy devices. Big-endian is indicated
+ with state.num set to true, and little-endian is indicated with state.num
+ set to false.
+ This request should be sent only when VHOST_USER_PROTOCOL_F_CROSS_ENDIAN
+ has been negotiated.
+
+
Slave message types
-------------------
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 958ee09..006af1c 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -33,6 +33,7 @@ enum VhostUserProtocolFeature {
VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
VHOST_USER_PROTOCOL_F_NET_MTU = 4,
VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
+ VHOST_USER_PROTOCOL_F_CROSS_ENDIAN = 6,
VHOST_USER_PROTOCOL_F_MAX
};
@@ -63,6 +64,7 @@ typedef enum VhostUserRequest {
VHOST_USER_NET_SET_MTU = 20,
VHOST_USER_SET_SLAVE_REQ_FD = 21,
VHOST_USER_IOTLB_MSG = 22,
+ VHOST_USER_SET_VRING_ENDIAN = 23,
VHOST_USER_MAX
} VhostUserRequest;
@@ -367,8 +369,25 @@ static int vhost_user_set_vring_addr(struct vhost_dev *dev,
static int vhost_user_set_vring_endian(struct vhost_dev *dev,
struct vhost_vring_state *ring)
{
- error_report("vhost-user trying to send unhandled ioctl");
- return -1;
+ bool cross_endian = virtio_has_feature(dev->protocol_features,
+ VHOST_USER_PROTOCOL_F_CROSS_ENDIAN);
+ VhostUserMsg msg = {
+ .request = VHOST_USER_SET_VRING_ENDIAN,
+ .flags = VHOST_USER_VERSION,
+ .payload.state = *ring,
+ .size = sizeof(msg.payload.state),
+ };
+
+ if (!cross_endian) {
+ error_report("vhost-user trying to send unhandled ioctl");
+ return -1;
+ }
+
+ if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+ return -1;
+ }
+
+ return 0;
}
static int vhost_set_vring(struct vhost_dev *dev,
--
1.9.5