From: Carlos López <clopez@suse.de>
Date: Fri, 13 Mar 2026 12:20:42 +0000 (+0100)
Subject: KVM: VFIO: update coherency only if file was deleted
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=156615264fd3430e7f90b36f46076b2f6ec4a24a;p=thirdparty%2Fkernel%2Flinux.git

KVM: VFIO: update coherency only if file was deleted

When servicing a KVM_DEV_VFIO_FILE_DEL request, if a file is removed
from kv->file_list, kv->noncoherent needs to be updated, in case we
can revert to using coherent DMA. However, if we found no candidate
to remove, there is no need to re-scan the list, so do it only if a
matching file was found.

To simplify the control flow, use a mutex guard so that we can return
early from within the search loop if the maching file is found.

Signed-off-by: Carlos López <clopez@suse.de>
Reviewed-by: Alex Williamson <alex@shazbot.org>
Link: https://patch.msgid.link/20260313122040.1413091-7-clopez@suse.de
Signed-off-by: Sean Christopherson <seanjc@google.com>
---

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 2fee1e82f8f6..6cdc4e9a333a 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -190,27 +190,21 @@ static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
 	struct kvm_vfio *kv = dev->private;
 	struct kvm_vfio_file *kvf;
 	CLASS(fd, f)(fd);
-	int ret;
 
 	if (fd_empty(f))
 		return -EBADF;
 
-	ret = -ENOENT;
-
-	mutex_lock(&kv->lock);
+	guard(mutex)(&kv->lock);
 
 	list_for_each_entry(kvf, &kv->file_list, node) {
 		if (kvf->file == fd_file(f)) {
 			kvm_vfio_file_free(dev, kvf);
-			ret = 0;
-			break;
+			kvm_vfio_update_coherency(dev);
+			return 0;
 		}
 	}
 
-	kvm_vfio_update_coherency(dev);
-
-	mutex_unlock(&kv->lock);
-	return ret;
+	return -ENOENT;
 }
 
 #ifdef CONFIG_SPAPR_TCE_IOMMU