linux-kernel - [PATCH 4.12 35/84] kvm-vfio: Decouple only when we match a group

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Date:   Wed, 19 Jul 2017 11:43:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Alex Williamson <alex.williamson@...hat.com>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        Eric Auger <eric.auger@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 4.12 35/84] kvm-vfio: Decouple only when we match a group

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Williamson <alex.williamson@...hat.com>

commit e323369b2e204da4dc771bbddceef986f4bf85d5 upstream.

Unset-KVM and decrement-assignment only when we find the group in our
list.  Otherwise we can get out of sync if the user triggers this for
groups that aren't currently on our list.

Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Reviewed-by: Alexey Kardashevskiy <aik@...abs.ru>
Reviewed-by: Eric Auger <eric.auger@...hat.com>
Tested-by: Eric Auger <eric.auger@...hat.com>
Acked-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 virt/kvm/vfio.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -246,21 +246,20 @@ static int kvm_vfio_set_group(struct kvm
 				continue;
 
 			list_del(&kvg->node);
+			kvm_arch_end_assignment(dev->kvm);
+#ifdef CONFIG_SPAPR_TCE_IOMMU
+			kvm_spapr_tce_release_vfio_group(dev->kvm,
+							 kvg->vfio_group);
+#endif
+			kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 			kvm_vfio_group_put_external_user(kvg->vfio_group);
 			kfree(kvg);
 			ret = 0;
 			break;
 		}
 
-		kvm_arch_end_assignment(dev->kvm);
-
 		mutex_unlock(&kv->lock);
 
-#ifdef CONFIG_SPAPR_TCE_IOMMU
-		kvm_spapr_tce_release_vfio_group(dev->kvm, vfio_group);
-#endif
-		kvm_vfio_group_set_kvm(vfio_group, NULL);
-
 		kvm_vfio_group_put_external_user(vfio_group);
 
 		kvm_vfio_update_coherency(dev);