Re: [PATCH v10 16/16] KVM: SVM: Bypass DBG_DECRYPT API calls for unencrypted guest memory.

[kernel test robot <lkp@intel.com>]

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Hi Ashish,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on v5.11-rc6]
[also build test WARNING on next-20210125]
[cannot apply to kvm/linux-next tip/x86/mm tip/x86/core]
[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/Ashish-Kalra/KVM-SVM-Add-KVM_SEV-SEND_START-command/20210204-093647
base:    1048ba83fb1c00cd24172e23e8263972f6b5d9ac
config: i386-randconfig-r015-20210209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/c086cd5491c6b84adcffedc1bf798df758b18080
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Ashish-Kalra/KVM-SVM-Add-KVM_SEV-SEND_START-command/20210204-093647
        git checkout c086cd5491c6b84adcffedc1bf798df758b18080
        # 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 warnings (new ones prefixed by >>):

   arch/x86/kvm/svm/sev.c: In function 'handle_unencrypted_region':
>> arch/x86/kvm/svm/sev.c:945:18: warning: variable 'd_off' set but not used [-Wunused-but-set-variable]
     945 |  int len, s_off, d_off;
         |                  ^~~~~


vim +/d_off +945 arch/x86/kvm/svm/sev.c

   934	
   935	static int handle_unencrypted_region(struct kvm *kvm,
   936					     unsigned long vaddr,
   937					     unsigned long vaddr_end,
   938					     unsigned long dst_vaddr,
   939					     unsigned int size,
   940					     bool *is_decrypted)
   941	{
   942		struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
   943		struct page *page = NULL;
   944		gfn_t gfn_start, gfn_end;
 > 945		int len, s_off, d_off;
   946		int srcu_idx;
   947		int ret = 0;
   948	
   949		/* ensure hva_to_gfn translations remain valid */
   950		srcu_idx = srcu_read_lock(&kvm->srcu);
   951	
   952		if (!hva_to_gfn(kvm, vaddr, &gfn_start)) {
   953			srcu_read_unlock(&kvm->srcu, srcu_idx);
   954			return -EINVAL;
   955		}
   956	
   957		if (!hva_to_gfn(kvm, vaddr_end, &gfn_end)) {
   958			srcu_read_unlock(&kvm->srcu, srcu_idx);
   959			return -EINVAL;
   960		}
   961	
   962		if (sev->shared_pages_list_count) {
   963			if (is_unencrypted_region(gfn_start, gfn_end,
   964						  &sev->shared_pages_list)) {
   965				page = alloc_page(GFP_KERNEL);
   966				if (!page) {
   967					srcu_read_unlock(&kvm->srcu, srcu_idx);
   968					return -ENOMEM;
   969				}
   970	
   971				/*
   972				 * Since user buffer may not be page aligned, calculate the
   973				 * offset within the page.
   974				 */
   975				s_off = vaddr & ~PAGE_MASK;
   976				d_off = dst_vaddr & ~PAGE_MASK;
   977				len = min_t(size_t, (PAGE_SIZE - s_off), size);
   978	
   979				if (copy_from_user(page_address(page),
   980						   (void __user *)(uintptr_t)vaddr, len)) {
   981					__free_page(page);
   982					srcu_read_unlock(&kvm->srcu, srcu_idx);
   983					return -EFAULT;
   984				}
   985	
   986				if (copy_to_user((void __user *)(uintptr_t)dst_vaddr,
   987						 page_address(page), len)) {
   988					ret = -EFAULT;
   989				}
   990	
   991				__free_page(page);
   992				srcu_read_unlock(&kvm->srcu, srcu_idx);
   993				*is_decrypted = true;
   994				return ret;
   995			}
   996		}
   997		srcu_read_unlock(&kvm->srcu, srcu_idx);
   998		*is_decrypted = false;
   999		return ret;
  1000	}
  1001	

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

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