From 5df04f1762ef78c08fd69e19dcedf3d9ba8c9b86 Mon Sep 17 00:00:00 2001 From: Felipe Franciosi Date: Wed, 14 Jun 2017 18:44:38 +0100 Subject: [PATCH] vhost-user: fix legacy cross-endian configurations 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 Signed-off-by: Mike Cui --- docs/interop/vhost-user.txt | 16 ++++++++++++++++ hw/virtio/vhost-user.c | 23 +++++++++++++++++++++-- 2 files changed, 37 insertions(+), 2 deletions(-) diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt index 481ab56e35..954771d0d8 100644 --- a/docs/interop/vhost-user.txt +++ b/docs/interop/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 +581,21 @@ 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: 23 + Equivalent ioctl: VHOST_SET_VRING_ENDIAN + Master payload: vring state description + + Set the endianess of a VQ for legacy devices. Little-endian is indicated + with state.num set to 0 and big-endian is indicated with state.num set + to 1. Other values are invalid. + This request should be sent only when VHOST_USER_PROTOCOL_F_CROSS_ENDIAN + has been negotiated. + Backends that negotiated this feature should handle both endianesses + and expect this message once (per VQ) during device configuration + (ie. before the master starts the VQ). + Slave message types ------------------- diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 2203011125..093675ed98 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,