From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:55344 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752946AbdDCNcA (ORCPT ); Mon, 3 Apr 2017 09:32:00 -0400 Subject: Patch "drm/i915/kvmgt: Hold struct kvm reference" has been added to the 4.10-stable tree To: alex.williamson@redhat.com, gregkh@linuxfoundation.org, jike.song@intel.com, pbonzini@redhat.com, zhenyuw@linux.intel.com, zhi.a.wang@intel.com Cc: , From: Date: Mon, 03 Apr 2017 15:30:45 +0200 Message-ID: <1491226245305@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled drm/i915/kvmgt: Hold struct kvm reference to the 4.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-i915-kvmgt-hold-struct-kvm-reference.patch and it can be found in the queue-4.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 93a15b58cfb8a24e666ffca432f19fe65c1cd7d1 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Sun, 19 Mar 2017 20:38:40 -0600 Subject: drm/i915/kvmgt: Hold struct kvm reference From: Alex Williamson commit 93a15b58cfb8a24e666ffca432f19fe65c1cd7d1 upstream. The kvmgt code keeps a pointer to the struct kvm associated with the device, but doesn't actually hold a reference to it. If we do unclean shutdown testing (ie. killing the user process), then we can see the kvm association to the device unset, which causes kvmgt to trigger a device release via a work queue. Naturally we cannot guarantee that the cached struct kvm pointer is still valid at this point without holding a reference. The observed failure in this case is a stuck cpu trying to acquire the spinlock from the invalid reference, but other failure modes are clearly possible. Hold a reference to avoid this. Signed-off-by: Alex Williamson Cc: Jike Song Cc: Paolo Bonzini Cc: Zhenyu Wang Cc: Zhi Wang Reviewed-by: Jike Song Signed-off-by: Zhenyu Wang Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/gvt/kvmgt.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/gpu/drm/i915/gvt/kvmgt.c +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -1334,6 +1334,7 @@ static int kvmgt_guest_init(struct mdev_ vgpu->handle = (unsigned long)info; info->vgpu = vgpu; info->kvm = kvm; + kvm_get_kvm(info->kvm); kvmgt_protect_table_init(info); gvt_cache_init(vgpu); @@ -1353,6 +1354,7 @@ static bool kvmgt_guest_exit(struct kvmg } kvm_page_track_unregister_notifier(info->kvm, &info->track_node); + kvm_put_kvm(info->kvm); kvmgt_protect_table_destroy(info); gvt_cache_destroy(info->vgpu); vfree(info); Patches currently in stable-queue which might be from alex.williamson@redhat.com are queue-4.10/drm-i915-kvmgt-hold-struct-kvm-reference.patch