[bug report] kvm: mmu: Don't expose private memslots to L2

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Jim Mattson,

The patch 3a2936dedd20: "kvm: mmu: Don't expose private memslots to
L2" from May 9, 2018, leads to the following static checker warning:

	arch/x86/kvm/mmu.c:3334 nonpaging_map()
	error: uninitialized symbol 'map_writable'.

arch/x86/kvm/mmu.c
  3315          if (fast_page_fault(vcpu, v, level, error_code))
  3316                  return RET_PF_RETRY;
  3317  
  3318          mmu_seq = vcpu->kvm->mmu_notifier_seq;
  3319          smp_rmb();
  3320  
  3321          if (try_async_pf(vcpu, prefault, gfn, v, &pfn, write, &map_writable))
                                                                       ^^^^^^^^^^^^
After that patch we return false but don't initialize *writable.

  3322                  return RET_PF_RETRY;
  3323  
  3324          if (handle_abnormal_pfn(vcpu, v, gfn, pfn, ACC_ALL, &r))
  3325                  return r;
  3326  
  3327          spin_lock(&vcpu->kvm->mmu_lock);
  3328          if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
  3329                  goto out_unlock;
  3330          if (make_mmu_pages_available(vcpu) < 0)
  3331                  goto out_unlock;
  3332          if (likely(!force_pt_level))
  3333                  transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
  3334          r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault);
                                              ^^^^^^^^^^^^

  3335          spin_unlock(&vcpu->kvm->mmu_lock);

regards,
dan carpenter