linux-kernel - [PATCH v3 2/9] kvm-vfio: Decouple only when we match a group

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Date:   Tue, 20 Jun 2017 09:47:50 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Alexey Kardashevskiy <aik@...abs.ru>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, linux@...linux.org.uk,
        eric.auger@...hat.com, alex.williamson@...hat.com,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH v3 2/9] kvm-vfio: Decouple only when we match a group

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>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Eric Auger <eric.auger@...hat.com>
Cc: stable@...r.kernel.org
---
 virt/kvm/vfio.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 37d9118fd84b..6e002d0f3191 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -246,21 +246,20 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 				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);