From b027f55a994af885a7a498a40373a2dcc2d8b15e Mon Sep 17 00:00:00 2001
From: Konstantin Shkolnyy <kshk@linux.ibm.com>
Date: Fri, 21 Feb 2025 13:07:33 -0600
Subject: vdpa: Allow vDPA to work on big-endian machine
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Add .set_vnet_le() function that always returns success, assuming that
vDPA h/w always implements LE data format. Otherwise, QEMU disables vDPA and
outputs the message:
"backend does not support LE vnet headers; falling back on userspace virtio"
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Konstantin Shkolnyy <kshk@linux.ibm.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
net/vhost-vdpa.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index f7a54f4..7ca8b46 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -262,6 +262,18 @@ static bool vhost_vdpa_has_ufo(NetClientState *nc)
}
+/*
+ * FIXME: vhost_vdpa doesn't have an API to "set h/w endianness". But it's
+ * reasonable to assume that h/w is LE by default, because LE is what
+ * virtio 1.0 and later ask for. So, this function just says "yes, the h/w is
+ * LE". Otherwise, on a BE machine, higher-level code would mistakely think
+ * the h/w is BE and can't support VDPA for a virtio 1.0 client.
+ */
+static int vhost_vdpa_set_vnet_le(NetClientState *nc, bool enable)
+{
+ return 0;
+}
+
static bool vhost_vdpa_check_peer_type(NetClientState *nc, ObjectClass *oc,
Error **errp)
{
@@ -429,6 +441,7 @@ static NetClientInfo net_vhost_vdpa_info = {
.cleanup = vhost_vdpa_cleanup,
.has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
.has_ufo = vhost_vdpa_has_ufo,
+ .set_vnet_le = vhost_vdpa_set_vnet_le,
.check_peer_type = vhost_vdpa_check_peer_type,
.set_steering_ebpf = vhost_vdpa_set_steering_ebpf,
};
--
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