linux-kernel - [PATCH 1/2] drm/i915/gvt: Get reference to KVM iff attachment to VM is successful

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Date:   Fri, 11 Nov 2022 00:22:24 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi Wang <zhi.a.wang@...el.com>
Cc:     intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH 1/2] drm/i915/gvt: Get reference to KVM iff attachment to VM
 is successful

Get a reference to KVM if and only if a vGPU is successfully attached to
the VM to avoid leaking a reference if there's no available vGPU.  On
open_device() failure, vfio_device_open() doesn't invoke close_device().

Fixes: 421cfe6596f6 ("vfio: remove VFIO_GROUP_NOTIFY_SET_KVM")
Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 drivers/gpu/drm/i915/gvt/kvmgt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 7a45e5360caf..e67d5267fde0 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -664,8 +664,6 @@ static int intel_vgpu_open_device(struct vfio_device *vfio_dev)
 		return -ESRCH;
 	}
 
-	kvm_get_kvm(vgpu->vfio_device.kvm);
-
 	if (__kvmgt_vgpu_exist(vgpu))
 		return -EEXIST;
 
@@ -676,6 +674,7 @@ static int intel_vgpu_open_device(struct vfio_device *vfio_dev)
 
 	vgpu->track_node.track_write = kvmgt_page_track_write;
 	vgpu->track_node.track_flush_slot = kvmgt_page_track_flush_slot;
+	kvm_get_kvm(vgpu->vfio_device.kvm);
 	kvm_page_track_register_notifier(vgpu->vfio_device.kvm,
 					 &vgpu->track_node);
 
-- 
2.38.1.431.g37b22c650d-goog