linux-kernel - [PATCH] Netvsc: Call hv_unmap_memory() in the netvsc_device

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Message-Id: <20220201163211.467423-1-ltykernel@gmail.com>
Date:   Tue,  1 Feb 2022 11:32:11 -0500
From:   Tianyu Lan <ltykernel@...il.com>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, davem@...emloft.net,
        kuba@...nel.org, hch@...radead.org, m.szyprowski@...sung.com,
        robin.murphy@....com, michael.h.kelley@...rosoft.com
Cc:     Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        iommu@...ts.linux-foundation.org, linux-hyperv@...r.kernel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH] Netvsc: Call hv_unmap_memory() in the netvsc_device_remove()

From: Tianyu Lan <Tianyu.Lan@...rosoft.com>

netvsc_device_remove() calls vunmap() inside which should not be
called in the interrupt context. Current code calls hv_unmap_memory()
in the free_netvsc_device() which is rcu callback and maybe called
in the interrupt context. This will trigger BUG_ON(in_interrupt())
in the vunmap(). Fix it via moving hv_unmap_memory() to netvsc_device_
remove().

Fixes: 846da38de0e8 ("net: netvsc: Add Isolation VM support for netvsc driver")
Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
---
 drivers/net/hyperv/netvsc.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index afa81a9480cc..f989f920d4ce 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -154,19 +154,15 @@ static void free_netvsc_device(struct rcu_head *head)
 
 	kfree(nvdev->extension);
 
-	if (nvdev->recv_original_buf) {
-		hv_unmap_memory(nvdev->recv_buf);
+	if (nvdev->recv_original_buf)
 		vfree(nvdev->recv_original_buf);
-	} else {
+	else
 		vfree(nvdev->recv_buf);
-	}
 
-	if (nvdev->send_original_buf) {
-		hv_unmap_memory(nvdev->send_buf);
+	if (nvdev->send_original_buf)
 		vfree(nvdev->send_original_buf);
-	} else {
+	else
 		vfree(nvdev->send_buf);
-	}
 
 	bitmap_free(nvdev->send_section_map);
 
@@ -765,6 +761,12 @@ void netvsc_device_remove(struct hv_device *device)
 		netvsc_teardown_send_gpadl(device, net_device, ndev);
 	}
 
+	if (net_device->recv_original_buf)
+		hv_unmap_memory(net_device->recv_buf);
+
+	if (net_device->send_original_buf)
+		hv_unmap_memory(net_device->send_buf);
+
 	/* Release all resources */
 	free_netvsc_device_rcu(net_device);
 }
-- 
2.25.1