From: Haiyang Zhang <haiyangz@microsoft.com>

Date: Thu, 6 Feb 2020 14:01:05 -0800

Patch-mainline: v5.6-rc1

Subject: hv_netvsc: Fix XDP refcnt for synthetic and VF NICs

Git-commit: 184367dce4f744bde54377203305ccc8889aa79f

References: bsc#1177819, bsc#1177820

MIME-Version: 1.0

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The caller of XDP_SETUP_PROG has already incremented refcnt in

__bpf_prog_get(), so drivers should only increment refcnt by

num_queues - 1.

To fix the issue, update netvsc_xdp_set() to add the correct number

to refcnt.

Hold a refcnt in netvsc_xdp_set()’s other caller, netvsc_attach().

And, do the same in netvsc_vf_setxdp(). Otherwise, every time when VF is

removed and added from the host side, the refcnt will be decreased by one,

which may cause page fault when unloading xdp program.

Fixes: 351e1581395f ("hv_netvsc: Add XDP support")

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

Acked-by: Olaf Hering <ohering@suse.de>

---

 drivers/net/hyperv/netvsc_bpf.c | 13 +++++++++++--

 drivers/net/hyperv/netvsc_drv.c |  5 ++++-

 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_bpf.c b/drivers/net/hyperv/netvsc_bpf.c

--- a/drivers/net/hyperv/netvsc_bpf.c

+++ b/drivers/net/hyperv/netvsc_bpf.c

@@ -120,7 +120,7 @@ int netvsc_xdp_set(struct net_device *dev, struct bpf_prog *prog,

 	}

 	if (prog)

-		bpf_prog_add(prog, nvdev->num_chn);

+		bpf_prog_add(prog, nvdev->num_chn - 1);

 	for (i = 0; i < nvdev->num_chn; i++)

 		rcu_assign_pointer(nvdev->chan_table[i].bpf_prog, prog);

@@ -136,6 +136,7 @@ int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog)

 {

 	struct netdev_bpf xdp;

 	bpf_op_t ndo_bpf;

+	int ret;

 	ASSERT_RTNL();

@@ -148,10 +149,18 @@ int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog)

 	memset(&xdp, 0, sizeof(xdp));

+	if (prog)

+		bpf_prog_inc(prog);

+

 	xdp.command = XDP_SETUP_PROG;

 	xdp.prog = prog;

-	return ndo_bpf(vf_netdev, &xdp;;

+	ret = ndo_bpf(vf_netdev, &xdp;;

+

+	if (ret && prog)

+		bpf_prog_put(prog);

+

+	return ret;

 }

 static u32 netvsc_xdp_query(struct netvsc_device *nvdev)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c

--- a/drivers/net/hyperv/netvsc_drv.c

+++ b/drivers/net/hyperv/netvsc_drv.c

@@ -1059,9 +1059,12 @@ static int netvsc_attach(struct net_device *ndev,

 	prog = dev_info->bprog;

 	if (prog) {

+		bpf_prog_inc(prog);

 		ret = netvsc_xdp_set(ndev, prog, NULL, nvdev);

-		if (ret)

+		if (ret) {

+			bpf_prog_put(prog);

 			goto err1;

+		}

 	}

 	/* In any case device is now ready */