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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "David S . Miller" <davem@davemloft.net>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.14 10/67] hv_netvsc: Fix the receive buffer size
 limit
Thread-Topic: [PATCH AUTOSEL for 4.14 10/67] hv_netvsc: Fix the receive buffer
 size limit
Thread-Index: AQHTtpn5t0FHs5gbF0G4TDTUa93nHg==
Date:   Thu, 8 Mar 2018 04:57:35 +0000
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From: Haiyang Zhang <haiyangz@microsoft.com>

[ Upstream commit 11b2b653102571ac791885324371d9a1a17b900e ]

The max should be 31 MB on host with NVSP version > 2.

On legacy hosts (NVSP version <=3D2) only 15 MB receive buffer is allowed,
otherwise the buffer request will be rejected by the host, resulting
vNIC not coming up.

The NVSP version is only available after negotiation. So, we add the
limit checking for legacy hosts in netvsc_init_buf().

Fixes: 5023a6db73196 ("netvsc: increase default receive buffer size")
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/net/hyperv/hyperv_net.h | 6 ++++--
 drivers/net/hyperv/netvsc.c     | 5 +++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_ne=
t.h
index 5176be76ca7d..04e9852ab804 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -635,9 +635,11 @@ struct nvsp_message {
 #define NETVSC_MTU 65535
 #define NETVSC_MTU_MIN ETH_MIN_MTU
=20
-#define NETVSC_RECEIVE_BUFFER_SIZE		(1024*1024*16)	/* 16MB */
-#define NETVSC_RECEIVE_BUFFER_SIZE_LEGACY	(1024*1024*15)  /* 15MB */
+/* Max buffer sizes allowed by a host */
+#define NETVSC_RECEIVE_BUFFER_SIZE		(1024 * 1024 * 31) /* 31MB */
+#define NETVSC_RECEIVE_BUFFER_SIZE_LEGACY	(1024 * 1024 * 15) /* 15MB */
 #define NETVSC_SEND_BUFFER_SIZE			(1024 * 1024 * 15)   /* 15MB */
+
 #define NETVSC_INVALID_INDEX			-1
=20
 #define NETVSC_SEND_SECTION_SIZE		6144
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 8d5077fb0492..a6bafcf55776 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -262,6 +262,11 @@ static int netvsc_init_buf(struct hv_device *device,
 	buf_size =3D device_info->recv_sections * device_info->recv_section_size;
 	buf_size =3D roundup(buf_size, PAGE_SIZE);
=20
+	/* Legacy hosts only allow smaller receive buffer */
+	if (net_device->nvsp_version <=3D NVSP_PROTOCOL_VERSION_2)
+		buf_size =3D min_t(unsigned int, buf_size,
+				 NETVSC_RECEIVE_BUFFER_SIZE_LEGACY);
+
 	net_device->recv_buf =3D vzalloc(buf_size);
 	if (!net_device->recv_buf) {
 		netdev_err(ndev,
--=20
2.14.1