linux-kernel - [PATCH] vhost-vdpa: switch to use vmf_insert

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Message-ID: <20240701033159.18133-1-jasowang@redhat.com>
Date: Mon,  1 Jul 2024 11:31:59 +0800
From: Jason Wang <jasowang@...hat.com>
To: mst@...hat.com,
	jasowang@...hat.com,
	eperezma@...hat.com
Cc: kvm@...r.kernel.org,
	virtualization@...ts.linux.dev,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Dragos Tatulea <dtatulea@...dia.com>,
	stable@...r.kernel.org
Subject: [PATCH] vhost-vdpa: switch to use vmf_insert_pfn() in the fault handler

remap_pfn_page() should not be called in the fault handler as it may
change the vma->flags which may trigger lockdep warning since the vma
write lock is not held. Actually there's no need to modify the
vma->flags as it has been set in the mmap(). So this patch switches to
use vmf_insert_pfn() instead.

Reported-by: Dragos Tatulea <dtatulea@...dia.com>
Tested-by: Dragos Tatulea <dtatulea@...dia.com>
Fixes: ddd89d0a059d ("vhost_vdpa: support doorbell mapping via mmap")
Cc: stable@...r.kernel.org
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
 drivers/vhost/vdpa.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 63a53680a85c..6b9c12acf438 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -1483,13 +1483,7 @@ static vm_fault_t vhost_vdpa_fault(struct vm_fault *vmf)
 
 	notify = ops->get_vq_notification(vdpa, index);
 
-	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-	if (remap_pfn_range(vma, vmf->address & PAGE_MASK,
-			    PFN_DOWN(notify.addr), PAGE_SIZE,
-			    vma->vm_page_prot))
-		return VM_FAULT_SIGBUS;
-
-	return VM_FAULT_NOPAGE;
+	return vmf_insert_pfn(vma, vmf->address & PAGE_MASK, PFN_DOWN(notify.addr));
 }
 
 static const struct vm_operations_struct vhost_vdpa_vm_ops = {
-- 
2.31.1