Hi David, I love your patch! Perhaps something to improve: [auto build test WARNING on linus/master] [also build test WARNING on next-20211118] [cannot apply to kvm/queue kvms390/next powerpc/topic/ppc-kvm kvmarm/next mst-vhost/linux-next v5.16-rc1] [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-Woodhouse/KVM-Introduce-CO... base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a90af8f15bdc9449ee2d24e1d73fa3f7e8633f81 config: i386-randconfig-s001-20211118 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.4-dirty # https://github.com/0day-ci/linux/commit/a9a90c7ab5f10064f2153f60e2410222c... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review David-Woodhouse/KVM-Introduce-CONFIG_HAVE_KVM_DIRTY_RING/20211120-192837 git checkout a9a90c7ab5f10064f2153f60e2410222c1b00700 # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) arch/x86/kvm/xen.c:272:22: sparse: expected void const [noderef] __user *ptr arch/x86/kvm/xen.c:272:22: sparse: got void * arch/x86/kvm/xen.c:276:56: sparse: expected struct vcpu_info [noderef] __user *vi arch/x86/kvm/xen.c:276:56: sparse: got void * arch/x86/kvm/xen.c:294:63: sparse: expected struct compat_vcpu_info [noderef] __user *vi arch/x86/kvm/xen.c:294:63: sparse: got void * vim +272 arch/x86/kvm/xen.c 196 197 int __kvm_xen_has_interrupt(struct kvm_vcpu *v) 198 { 199 unsigned long evtchn_pending_sel = READ_ONCE(v->arch.xen.evtchn_pending_sel); 200 bool atomic = in_atomic() || !task_is_running(current); 201 int err; 202 u8 rc = 0; 203 204 /* 205 * If the global upcall vector (HVMIRQ_callback_vector) is set and 206 * the vCPU's evtchn_upcall_pending flag is set, the IRQ is pending. 207 */ 208 struct gfn_to_hva_cache *ghc = &v->arch.xen.vcpu_info_cache; 209 struct kvm_memslots *slots = kvm_memslots(v->kvm); 210 bool ghc_valid = slots->generation == ghc->generation && 211 !kvm_is_error_hva(ghc->hva) && ghc->memslot; 212 213 unsigned int offset = offsetof(struct vcpu_info, evtchn_upcall_pending); 214 215 /* No need for compat handling here */ 216 BUILD_BUG_ON(offsetof(struct vcpu_info, evtchn_upcall_pending) != 217 offsetof(struct compat_vcpu_info, evtchn_upcall_pending)); 218 BUILD_BUG_ON(sizeof(rc) != 219 sizeof_field(struct vcpu_info, evtchn_upcall_pending)); 220 BUILD_BUG_ON(sizeof(rc) != 221 sizeof_field(struct compat_vcpu_info, evtchn_upcall_pending)); 222 223 /* 224 * For efficiency, this mirrors the checks for using the valid 225 * cache in kvm_read_guest_offset_cached(), but just uses 226 * __get_user() instead. And falls back to the slow path. 227 */ 228 if (!evtchn_pending_sel && ghc_valid) { 229 /* Fast path */ 230 pagefault_disable(); 231 err = __get_user(rc, (u8 __user *)ghc->hva + offset); 232 pagefault_enable(); 233 if (!err) 234 return rc; 235 } 236 237 /* Slow path */ 238 239 /* 240 * This function gets called from kvm_vcpu_block() after setting the 241 * task to TASK_INTERRUPTIBLE, to see if it needs to wake immediately 242 * from a HLT. So we really mustn't sleep. If the page ended up absent 243 * at that point, just return 1 in order to trigger an immediate wake, 244 * and we'll end up getting called again from a context where we *can* 245 * fault in the page and wait for it. 246 */ 247 if (atomic) 248 return 1; 249 250 if (!ghc_valid) { 251 err = kvm_gfn_to_hva_cache_init(v->kvm, ghc, ghc->gpa, ghc->len); 252 if (err || !ghc->memslot) { 253 /* 254 * If this failed, userspace has screwed up the 255 * vcpu_info mapping. No interrupts for you. 256 */ 257 return 0; 258 } 259 } 260 261 /* 262 * Now we have a valid (protected by srcu) userspace HVA in 263 * ghc->hva which points to the struct vcpu_info. If there 264 * are any bits in the in-kernel evtchn_pending_sel then 265 * we need to write those to the guest vcpu_info and set 266 * its evtchn_upcall_pending flag. If there aren't any bits 267 * to add, we only want to *check* evtchn_upcall_pending. 268 */ 269 if (evtchn_pending_sel) { 270 bool long_mode = v->kvm->arch.xen.long_mode; 271 273 return 0; 274 275 if (IS_ENABLED(CONFIG_64BIT) && long_mode) { 277 278 /* Attempt to set the evtchn_pending_sel bits in the 279 * guest, and if that succeeds then clear the same 280 * bits in the in-kernel version. */ 281 asm volatile("1:\t" LOCK_PREFIX "orq %0, %1\n" 282 "\tnotq %0\n" 283 "\t" LOCK_PREFIX "andq %0, %2\n" 284 "2:\n" 285 "\t.section .fixup,\"ax\"\n" 286 "3:\tjmp\t2b\n" 287 "\t.previous\n" 288 _ASM_EXTABLE_UA(1b, 3b) 289 : "=r" (evtchn_pending_sel), 290 "+m" (vi->evtchn_pending_sel), 291 "+m" (v->arch.xen.evtchn_pending_sel) 292 : "0" (evtchn_pending_sel)); 293 } else { 295 u32 evtchn_pending_sel32 = evtchn_pending_sel; 296 297 /* Attempt to set the evtchn_pending_sel bits in the 298 * guest, and if that succeeds then clear the same 299 * bits in the in-kernel version. */ 300 asm volatile("1:\t" LOCK_PREFIX "orl %0, %1\n" 301 "\tnotl %0\n" 302 "\t" LOCK_PREFIX "andl %0, %2\n" 303 "2:\n" 304 "\t.section .fixup,\"ax\"\n" 305 "3:\tjmp\t2b\n" 306 "\t.previous\n" 307 _ASM_EXTABLE_UA(1b, 3b) 308 : "=r" (evtchn_pending_sel32), 309 "+m" (vi->evtchn_pending_sel), 310 "+m" (v->arch.xen.evtchn_pending_sel) 311 : "0" (evtchn_pending_sel32)); 312 } 313 rc = 1; 314 unsafe_put_user(rc, (u8 __user *)ghc->hva + offset, err); 315 316 err: 317 user_access_end(); 318 319 mark_page_dirty_in_slot(v->kvm, ghc->memslot, ghc->gpa >> PAGE_SHIFT); 320 } else { 321 __get_user(rc, (u8 __user *)ghc->hva + offset); 322 } 323 324 return rc; 325 } 326 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org