From 5df04f1762ef78c08fd69e19dcedf3d9ba8c9b86 Mon Sep 17 00:00:00 2001 From: Felipe Franciosi Date: Wed, 14 Jun 2017 18:44:38 +0100 Subject: 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 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'docs/interop') 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 ------------------- -- cgit v1.2.3