Hi Matthew, I love your patch! Perhaps something to improve: [auto build test WARNING on v5.16-rc4] [cannot apply to s390/features kvms390/next awilliam-vfio/next next-20211207] [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/Matthew-Rosato/KVM-s390-enable-z... base: 0fcfb00b28c0b7884635dacf38e46d60bf3d4eb1 config: s390-allyesconfig (https://download.01.org/0day-ci/archive/20211208/202112081537.qiFqvLb1-lk...) compiler: s390-linux-gcc (GCC) 11.2.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/0day-ci/linux/commit/84cb5df859beb99f52b3d3b133ff1f9b5... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Matthew-Rosato/KVM-s390-enable-zPCI-for-interpretive-execution/20211208-050204 git checkout 84cb5df859beb99f52b3d3b133ff1f9b5a459558 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=s390 SHELL=/bin/bash arch/s390/kvm/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): 179 | unsigned long *dma_walk_guest_cpu_trans(struct kvm_vcpu *vcpu, | ^~~~~~~~~~~~~~~~~~~~~~~~ vim +/dma_walk_guest_cpu_trans +179 arch/s390/kvm/pci.c 178 180 struct kvm_zdev_ioat *ioat, 181 dma_addr_t dma_addr) 182 { 183 unsigned long *rto, *sto, *pto; 184 unsigned int rtx, rts, sx, px, idx; 185 struct page *page; 186 gpa_t addr; 187 int i; 188 189 /* Pin guest segment table if needed */ 190 rtx = calc_rtx(dma_addr); 191 rto = ioat->head[(rtx / ZPCI_TABLE_ENTRIES_PER_PAGE)]; 192 rts = rtx * ZPCI_TABLE_PAGES; 193 if (!ioat->seg[rts]) { 194 if (!reg_entry_isvalid(rto[rtx % ZPCI_TABLE_ENTRIES_PER_PAGE])) 195 return NULL; 196 sto = get_rt_sto(rto[rtx % ZPCI_TABLE_ENTRIES_PER_PAGE]); 197 addr = ((u64)sto & ZPCI_RTE_ADDR_MASK); 198 idx = srcu_read_lock(&vcpu->kvm->srcu); 199 for (i = 0; i < ZPCI_TABLE_PAGES; i++) { 200 page = gfn_to_page(vcpu->kvm, gpa_to_gfn(addr)); 201 if (is_error_page(page)) { 202 srcu_read_unlock(&vcpu->kvm->srcu, idx); 203 return NULL; 204 } 205 ioat->seg[rts + i] = page_to_virt(page) + 206 (addr & ~PAGE_MASK); 207 addr += PAGE_SIZE; 208 } 209 srcu_read_unlock(&vcpu->kvm->srcu, idx); 210 } 211 212 /* Allocate pin pointers for another segment table if needed */ 213 if (!ioat->pt[rtx]) { 214 ioat->pt[rtx] = kcalloc(ZPCI_TABLE_ENTRIES, 215 (sizeof(unsigned long *)), GFP_KERNEL); 216 if (!ioat->pt[rtx]) 217 return NULL; 218 } 219 /* Pin guest page table if needed */ 220 sx = calc_sx(dma_addr); 221 sto = ioat->seg[(rts + (sx / ZPCI_TABLE_ENTRIES_PER_PAGE))]; 222 if (!ioat->pt[rtx][sx]) { 223 if (!reg_entry_isvalid(sto[sx % ZPCI_TABLE_ENTRIES_PER_PAGE])) 224 return NULL; 225 pto = get_st_pto(sto[sx % ZPCI_TABLE_ENTRIES_PER_PAGE]); 226 if (!pto) 227 return NULL; 228 addr = ((u64)pto & ZPCI_STE_ADDR_MASK); 229 idx = srcu_read_lock(&vcpu->kvm->srcu); 230 page = gfn_to_page(vcpu->kvm, gpa_to_gfn(addr)); 231 srcu_read_unlock(&vcpu->kvm->srcu, idx); 232 if (is_error_page(page)) 233 return NULL; 234 ioat->pt[rtx][sx] = page_to_virt(page) + (addr & ~PAGE_MASK); 235 } 236 pto = ioat->pt[rtx][sx]; 237 238 /* Return guest PTE */ 239 px = calc_px(dma_addr); 240 return &pto[px]; 241 } 242 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org