diff mbox series

[2/2] drm/i915/gvt: Unconditionally put reference to KVM when detaching vGPU

Message ID 20221111002225.2418386-3-seanjc@google.com
State New
Headers
Series drm/i915/gvt: Fix for KVM refcounting bug |

Commit Message

Sean Christopherson Nov. 11, 2022, 12:22 a.m. UTC 
  Always put the KVM reference when closing a vCPU device, as
intel_vgpu_open_device() succeeds if and only if the KVM pointer is
valid and a reference to KVM is acquired.  And if that doesn't hold true,
the call to kvm_page_track_unregister_notifier() a few lines earlier is
doomed.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 drivers/gpu/drm/i915/gvt/kvmgt.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Comments

Tian, Kevin Nov. 11, 2022, 2:50 a.m. UTC | #1 
> From: Sean Christopherson <seanjc@google.com>
> Sent: Friday, November 11, 2022 8:22 AM
> 
> Always put the KVM reference when closing a vCPU device, as
> intel_vgpu_open_device() succeeds if and only if the KVM pointer is
> valid and a reference to KVM is acquired.  And if that doesn't hold true,
> the call to kvm_page_track_unregister_notifier() a few lines earlier is
> doomed.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index e67d5267fde0..714221f9a131 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -714,15 +714,14 @@  static void intel_vgpu_close_device(struct vfio_device *vfio_dev)
 
 	kvm_page_track_unregister_notifier(vgpu->vfio_device.kvm,
 					   &vgpu->track_node);
+	kvm_put_kvm(vgpu->vfio_device.kvm);
+
 	kvmgt_protect_table_destroy(vgpu);
 	gvt_cache_destroy(vgpu);
 
 	intel_vgpu_release_msi_eventfd_ctx(vgpu);
 
 	vgpu->attached = false;
-
-	if (vgpu->vfio_device.kvm)
-		kvm_put_kvm(vgpu->vfio_device.kvm);
 }
 
 static u64 intel_vgpu_get_bar_addr(struct intel_vgpu *vgpu, int bar)