From 1bfa316ce776d1f90ac96c59b4b69910db19ed6d Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Fri, 5 Feb 2016 11:43:11 +0100 Subject: virtio-net: use the backend cross-endian capabilities When running a fully emulated device in cross-endian conditions, including a virtio 1.0 device offered to a big endian guest, we need to fix the vnet headers. This is currently handled by the virtio_net_hdr_swap() function in the core virtio-net code but it should actually be handled by the net backend. With this patch, virtio-net now tries to configure the backend to do the endian fixing when the device starts (i.e. drivers sets the CONFIG_OK bit). If the backend cannot support the requested endiannes, we have to fallback onto virtio_net_hdr_swap(): this is recorded in the needs_vnet_hdr_swap flag, to be used in the TX and RX paths. Note that we reset the backend to the default behaviour (guest native endianness) when the device stops (i.e. device status had CONFIG_OK bit and driver unsets it). This is needed, with the linux tap backend at least, otherwise the guest may lose network connectivity if rebooted into a different endianness. The current vhost-net code also tries to configure net backends. This will be no more needed and will be reverted in a subsequent patch. Reviewed-by: Cornelia Huck Reviewed-by: Laurent Vivier Signed-off-by: Greg Kurz Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Laurent Vivier --- include/hw/virtio/virtio-net.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/hw/virtio/virtio-net.h') diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h index 2ce3b03bd4..0cabdb6822 100644 --- a/include/hw/virtio/virtio-net.h +++ b/include/hw/virtio/virtio-net.h @@ -94,6 +94,7 @@ typedef struct VirtIONet { uint64_t curr_guest_offloads; QEMUTimer *announce_timer; int announce_counter; + bool needs_vnet_hdr_swap; } VirtIONet; void virtio_net_set_netclient_name(VirtIONet *n, const char *name, -- cgit 1.4.1