Hi David,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kvm/queue]
[also build test ERROR on linus/master next-20210630]
[cannot apply to vhost/linux-next v5.13]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/David-Matlack/KVM-x86-mmu-Fast-page-fault-support-for-the-TDP-MMU/20210701-055009
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
config: i386-buildonly-randconfig-r001-20210630 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/7709823e6135aaf4aeac8235973f37e679064356
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review David-Matlack/KVM-x86-mmu-Fast-page-fault-support-for-the-TDP-MMU/20210701-055009
        git checkout 7709823e6135aaf4aeac8235973f37e679064356
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> arch/x86/kvm/mmu/mmu.c:3119:6: error: no previous prototype for 'get_last_sptep_lockless' [-Werror=missing-prototypes]
    3119 | u64 *get_last_sptep_lockless(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte)
         |      ^~~~~~~~~~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors


vim +/get_last_sptep_lockless +3119 arch/x86/kvm/mmu/mmu.c

  3107	
  3108	/*
  3109	 * Returns the last level spte pointer of the shadow page walk for the given
  3110	 * gpa, and sets *spte to the spte value. This spte may be non-preset.
  3111	 *
  3112	 * If no walk could be performed, returns NULL and *spte does not contain valid
  3113	 * data.
  3114	 *
  3115	 * Constraints:
  3116	 *  - Must be called between walk_shadow_page_lockless_{begin,end}.
  3117	 *  - The returned sptep must not be used after walk_shadow_page_lockless_end.
  3118	 */
> 3119	u64 *get_last_sptep_lockless(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte)
  3120	{
  3121		struct kvm_shadow_walk_iterator iterator;
  3122		u64 old_spte;
  3123		u64 *sptep = NULL;
  3124	
  3125		if (is_tdp_mmu(vcpu->arch.mmu))
  3126			return kvm_tdp_mmu_get_last_sptep_lockless(vcpu, gpa, spte);
  3127	
  3128		for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) {
  3129			sptep = iterator.sptep;
  3130			*spte = old_spte;
  3131	
  3132			if (!is_shadow_present_pte(old_spte))
  3133				break;
  3134		}
  3135	
  3136		return sptep;
  3137	}
  3138	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org