[PATCH] drm/i915/kvmgt: fix suspicious rcu dereference usage

[Zhenyu Wang]

On 2017.03.15 17:04:20 +0800, Jike Song wrote:
> On 03/13/2017 05:01 PM, Zhenyu Wang wrote:
> > 
> > On 2017.03.13 16:44:33 +0800, changbin.du at intel.com wrote:
> >> From: Changbin Du <changbin.du at intel.com>
> >>
> > 
> > I'm cc Guangrong to confirm kvm lock for this.
> > 
> >> The srcu read lock must be held while accessing kvm memslots.
> >> This patch fix below warning for function kvmgt_rw_gpa().
> >>
> >> [  165.345093] [ ERR: suspicious RCU usage.  ]
> >> [  165.416538] Call Trace:
> >> [  165.418989]  dump_stack+0x85/0xc2
> >> [  165.422310]  lockdep_rcu_suspicious+0xd7/0x110
> >> [  165.426769]  kvm_read_guest_page+0x195/0x1b0 [kvm]
> >> [  165.431574]  kvm_read_guest+0x50/0x90 [kvm]
> >> [  165.440492]  kvmgt_rw_gpa+0x43/0xa0 [kvmgt]
> >> [  165.444683]  kvmgt_read_gpa+0x11/0x20 [kvmgt]
> >> [  165.449061]  gtt_get_entry64+0x4d/0xc0 [i915]
> >> [  165.453438]  ppgtt_populate_shadow_page_by_guest_entry+0x380/0xdc0 [i915]
> >> [  165.460254]  shadow_mm+0xd1/0x460 [i915]
> >> [  165.472488]  intel_vgpu_create_mm+0x1ab/0x210 [i915]
> >> [  165.477472]  intel_vgpu_g2v_create_ppgtt_mm+0x5f/0xc0 [i915]
> >> [  165.483154]  pvinfo_mmio_write+0x19b/0x1d0 [i915]
> >> [  165.499068]  intel_vgpu_emulate_mmio_write+0x3f9/0x600 [i915]
> >> [  165.504827]  intel_vgpu_rw+0x114/0x150 [kvmgt]
> >> [  165.509281]  intel_vgpu_write+0x16f/0x1a0 [kvmgt]
> >> [  165.513993]  vfio_mdev_write+0x20/0x30 [vfio_mdev]
> >> [  165.518793]  vfio_device_fops_write+0x24/0x30 [vfio]
> >> [  165.523770]  __vfs_write+0x28/0x120
> >> [  165.540529]  vfs_write+0xce/0x1f0
> 
> Reviewed-by: Jike Song <jike.song at intel.com>
> 
> >>
> >> Signed-off-by: Changbin Du <changbin.du at intel.com>
> >> Cc: stable at kernel.org
> >> ---

Should be stable at vger.kernel.org. Could you resend with correct Cc:?
So once this is in linus tree, stable kernel team will pick this up.

-- 
Open Source Technology Center, Intel ltd.

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