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From: Si-Wei Liu <si-wei.liu@oracle.com>
To: mst@redhat.com, jasowang@redhat.com, elic@nvidia.com
Cc: linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, si-wei.liu@oracle.com
Subject: [PATCH v2 1/3] vdpa/mlx5: should exclude header length and fcs from mtu
Date: Wed, 10 Feb 2021 13:47:58 -0800 (PST)	[thread overview]
Message-ID: <1612993680-29454-2-git-send-email-si-wei.liu@oracle.com> (raw)
In-Reply-To: <1612993680-29454-1-git-send-email-si-wei.liu@oracle.com>

When feature VIRTIO_NET_F_MTU is negotiated on mlx5_vdpa,
22 extra bytes worth of MTU length is shown in guest.
This is because the mlx5_query_port_max_mtu API returns
the "hardware" MTU value, which does not just contain the
 Ethernet payload, but includes extra lengths starting
from the Ethernet header up to the FCS altogether.

Fix the MTU so packets won't get dropped silently.

Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Eli Cohen <elic@nvidia.com>
---
 drivers/vdpa/mlx5/core/mlx5_vdpa.h |  4 ++++
 drivers/vdpa/mlx5/net/mlx5_vnet.c  | 15 ++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
index 08f742f..b6cc53b 100644
--- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
+++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
@@ -4,9 +4,13 @@
 #ifndef __MLX5_VDPA_H__
 #define __MLX5_VDPA_H__
 
+#include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
 #include <linux/vdpa.h>
 #include <linux/mlx5/driver.h>
 
+#define MLX5V_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
+
 struct mlx5_vdpa_direct_mr {
 	u64 start;
 	u64 end;
diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index dc88559..b8416c4 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -1907,6 +1907,19 @@ static int mlx5_get_vq_irq(struct vdpa_device *vdv, u16 idx)
 	.free = mlx5_vdpa_free,
 };
 
+static int query_mtu(struct mlx5_core_dev *mdev, u16 *mtu)
+{
+	u16 hw_mtu;
+	int err;
+
+	err = mlx5_query_nic_vport_mtu(mdev, &hw_mtu);
+	if (err)
+		return err;
+
+	*mtu = hw_mtu - MLX5V_ETH_HARD_MTU;
+	return 0;
+}
+
 static int alloc_resources(struct mlx5_vdpa_net *ndev)
 {
 	struct mlx5_vdpa_net_resources *res = &ndev->res;
@@ -1992,7 +2005,7 @@ static int mlx5v_probe(struct auxiliary_device *adev,
 	init_mvqs(ndev);
 	mutex_init(&ndev->reslock);
 	config = &ndev->config;
-	err = mlx5_query_nic_vport_mtu(mdev, &ndev->mtu);
+	err = query_mtu(mdev, &ndev->mtu);
 	if (err)
 		goto err_mtu;
 
-- 
1.8.3.1


WARNING: multiple messages have this Message-ID (diff)
From: Si-Wei Liu <si-wei.liu@oracle.com>
To: mst@redhat.com, jasowang@redhat.com, elic@nvidia.com
Cc: si-wei.liu@oracle.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org
Subject: [PATCH v2 1/3] vdpa/mlx5: should exclude header length and fcs from mtu
Date: Wed, 10 Feb 2021 13:47:58 -0800 (PST)	[thread overview]
Message-ID: <1612993680-29454-2-git-send-email-si-wei.liu@oracle.com> (raw)
In-Reply-To: <1612993680-29454-1-git-send-email-si-wei.liu@oracle.com>

When feature VIRTIO_NET_F_MTU is negotiated on mlx5_vdpa,
22 extra bytes worth of MTU length is shown in guest.
This is because the mlx5_query_port_max_mtu API returns
the "hardware" MTU value, which does not just contain the
 Ethernet payload, but includes extra lengths starting
from the Ethernet header up to the FCS altogether.

Fix the MTU so packets won't get dropped silently.

Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Eli Cohen <elic@nvidia.com>
---
 drivers/vdpa/mlx5/core/mlx5_vdpa.h |  4 ++++
 drivers/vdpa/mlx5/net/mlx5_vnet.c  | 15 ++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
index 08f742f..b6cc53b 100644
--- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
+++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
@@ -4,9 +4,13 @@
 #ifndef __MLX5_VDPA_H__
 #define __MLX5_VDPA_H__
 
+#include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
 #include <linux/vdpa.h>
 #include <linux/mlx5/driver.h>
 
+#define MLX5V_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
+
 struct mlx5_vdpa_direct_mr {
 	u64 start;
 	u64 end;
diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index dc88559..b8416c4 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -1907,6 +1907,19 @@ static int mlx5_get_vq_irq(struct vdpa_device *vdv, u16 idx)
 	.free = mlx5_vdpa_free,
 };
 
+static int query_mtu(struct mlx5_core_dev *mdev, u16 *mtu)
+{
+	u16 hw_mtu;
+	int err;
+
+	err = mlx5_query_nic_vport_mtu(mdev, &hw_mtu);
+	if (err)
+		return err;
+
+	*mtu = hw_mtu - MLX5V_ETH_HARD_MTU;
+	return 0;
+}
+
 static int alloc_resources(struct mlx5_vdpa_net *ndev)
 {
 	struct mlx5_vdpa_net_resources *res = &ndev->res;
@@ -1992,7 +2005,7 @@ static int mlx5v_probe(struct auxiliary_device *adev,
 	init_mvqs(ndev);
 	mutex_init(&ndev->reslock);
 	config = &ndev->config;
-	err = mlx5_query_nic_vport_mtu(mdev, &ndev->mtu);
+	err = query_mtu(mdev, &ndev->mtu);
 	if (err)
 		goto err_mtu;
 
-- 
1.8.3.1

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  reply	other threads:[~2021-02-10 21:52 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-10 21:47 [PATCH v2 0/3] mlx5_vdpa bug fixes Si-Wei Liu
2021-02-10 21:47 ` Si-Wei Liu
2021-02-10 21:47 ` Si-Wei Liu [this message]
2021-02-10 21:47   ` [PATCH v2 1/3] vdpa/mlx5: should exclude header length and fcs from mtu Si-Wei Liu
2021-02-10 21:47 ` [PATCH v2 2/3] vdpa/mlx5: fix feature negotiation across device reset Si-Wei Liu
2021-02-10 21:47   ` Si-Wei Liu
2021-02-11  7:33   ` Eli Cohen
2021-02-18  6:36   ` Jason Wang
2021-02-18  6:36     ` Jason Wang
2021-02-10 21:48 ` [PATCH v2 3/3] vdpa/mlx5: defer clear_virtqueues to until DRIVER_OK Si-Wei Liu
2021-02-10 21:48   ` Si-Wei Liu
2021-02-11  7:33   ` Eli Cohen
2021-02-16 15:21     ` Eli Cohen
2021-02-17 21:55       ` Si-Wei Liu
2021-02-17 21:55         ` Si-Wei Liu
2021-02-18  6:37         ` Jason Wang
2021-02-18  6:37           ` Jason Wang

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