Subject: [PATCH net 2/3] hv_netvsc: Limit the receive buffer size for legacy hosts

From: Stephen Hemminger <[email-masked]>
Date: Thu, 7 Dec 2017 16:10:54 -0800

From: Haiyang Zhang <[email-masked]>

Legacy hosts only allow 15 MB receive buffer, and we know the
NVSP version only after negotiation. So, we put the limit in
netvsc_init_buf().

Fixes: 5023a6db73196 ("netvsc: increase default receive buffer size")
Signed-off-by: Haiyang Zhang <[email-masked]>
Signed-off-by: Stephen Hemminger <[email-masked]>
---
 drivers/net/hyperv/netvsc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index e4bcd202a56a..e5d16a8cf0d6 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -268,6 +268,11 @@ static int netvsc_init_buf(struct hv_device *device,
 	buf_size = device_info->recv_sections * device_info->recv_section_size;
 	buf_size = roundup(buf_size, PAGE_SIZE);
 
+	/* Legacy hosts only allow smaller receive buffer */
+	if (net_device->nvsp_version <= NVSP_PROTOCOL_VERSION_2)
+		buf_size = min_t(unsigned int, buf_size,
+				 NETVSC_RECEIVE_BUFFER_SIZE_LEGACY);
+
 	net_device->recv_buf = vzalloc(buf_size);
 	if (!net_device->recv_buf) {
 		netdev_err(ndev,
-- 
2.11.0