Re: [PATCH 01/11] KVM: arm64: Add snap shooting the host stage-2 pagetables

[kernel test robot]

Hi Sebastian,

kernel test robot noticed the following build warnings:

[auto build test WARNING on arm64/for-next/core]
[also build test WARNING on kvmarm/next linus/master v6.6-rc3 next-20230928]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sebastian-Ene/KVM-arm64-Add-snap-shooting-the-host-stage-2-pagetables/20230927-192734
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
patch link:    https://lore.kernel.org/r/20230927112517.2631674-2-sebastianene%40google.com
patch subject: [PATCH 01/11] KVM: arm64: Add snap shooting the host stage-2 pagetables
config: arm64-allyesconfig (https://download.01.org/0day-ci/archive/20230929/202309290210.m6jkiTXx-lkp@xxxxxxxxx/config)
compiler: aarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230929/202309290210.m6jkiTXx-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309290210.m6jkiTXx-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

   arch/arm64/kvm/hyp/nvhe/mem_protect.c: In function '__pkvm_host_stage2_prepare_copy':
>> arch/arm64/kvm/hyp/nvhe/mem_protect.c:335:13: warning: variable 'nr_pages' set but not used [-Wunused-but-set-variable]
     335 |         u64 nr_pages;
         |             ^~~~~~~~


vim +/nr_pages +335 arch/arm64/kvm/hyp/nvhe/mem_protect.c

   326	
   327	int __pkvm_host_stage2_prepare_copy(struct kvm_pgtable_snapshot *snapshot)
   328	{
   329		size_t required_pgd_len;
   330		struct kvm_pgtable_mm_ops mm_ops = {0};
   331		struct kvm_pgtable *to_pgt, *from_pgt = &host_mmu.pgt;
   332		struct kvm_hyp_memcache *memcache = &snapshot->mc;
   333		int ret;
   334		void *pgd;
 > 335		u64 nr_pages;
   336	
   337		required_pgd_len = kvm_pgtable_stage2_pgd_size(host_mmu.arch.vtcr);
   338		if (snapshot->pgd_len < required_pgd_len)
   339			return -ENOMEM;
   340	
   341		to_pgt = &snapshot->pgtable;
   342		nr_pages = snapshot->pgd_len / PAGE_SIZE;
   343		pgd = kern_hyp_va(snapshot->pgd_hva);
   344	
   345		hyp_spin_lock(&snapshot_pool_lock);
   346		hyp_pool_init(&snapshot_pool, hyp_virt_to_pfn(pgd),
   347			      required_pgd_len / PAGE_SIZE, 0);
   348	
   349		mm_ops.zalloc_pages_exact	= snapshot_zalloc_pages_exact;
   350		mm_ops.zalloc_page		= snapshot_zalloc_page;
   351		mm_ops.free_pages_exact		= snapshot_s2_free_pages_exact;
   352		mm_ops.get_page			= snapshot_get_page;
   353		mm_ops.phys_to_virt		= hyp_phys_to_virt;
   354		mm_ops.virt_to_phys		= hyp_virt_to_phys;
   355		mm_ops.page_count		= hyp_page_count;
   356	
   357		to_pgt->ia_bits		= from_pgt->ia_bits;
   358		to_pgt->start_level	= from_pgt->start_level;
   359		to_pgt->flags		= from_pgt->flags;
   360		to_pgt->mm_ops		= &mm_ops;
   361	
   362		host_lock_component();
   363		ret = kvm_pgtable_stage2_copy(to_pgt, from_pgt, memcache);
   364		host_unlock_component();
   365	
   366		hyp_spin_unlock(&snapshot_pool_lock);
   367	
   368		return ret;
   369	}
   370	#endif /* CONFIG_NVHE_EL2_DEBUG */
   371	

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