Re: [PATCH v6 12/14] KVM: s390: Extend MEM_OP ioctl by storage key checked cmpxchg

kernel test robot
2023-01-28T14:38:45Z

Hi Janis,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kvm/queue]
[also build test ERROR on lwn/docs-next linus/master v6.2-rc5 next-20230127]
[cannot apply to kvms390/next kvm/linux-next]
[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/Janis-Schoetterl-Glausch/KVM-s390-selftest-memop-Pass-mop_desc-via-pointer/20230128-132603
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
patch link: https://lore.kernel.org/r/20230125212608.1860251-13-scgl%40linux.ibm.com
patch subject: [PATCH v6 12/14] KVM: s390: Extend MEM_OP ioctl by storage key checked cmpxchg
config: s390-randconfig-r044-20230123 (https://download.01.org/0day-ci/archive/20230128/202301282223.YafIuB1E-lkp@intel.com/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 4196ca3278f78c6e19246e54ab0ecb364e37d66a)
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
# install s390 cross compiling tool for clang build
# apt-get install binutils-s390x-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/6e6b3d99b9978a70b148b989d46b039feda3a3c3
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Janis-Schoetterl-Glausch/KVM-s390-selftest-memop-Pass-mop_desc-via-pointer/20230128-132603
git checkout 6e6b3d99b9978a70b148b989d46b039feda3a3c3
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash arch/s390/kvm/

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

All errors (new ones prefixed by >>):

In file included from arch/s390/kvm/gaccess.c:16:
In file included from arch/s390/kvm/kvm-s390.h:17:
In file included from include/linux/kvm_host.h:19:
In file included from include/linux/msi.h:27:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __raw_readb(PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:37:59: note: expanded from macro '__le16_to_cpu'
#define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
^
include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16'
#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
^
In file included from arch/s390/kvm/gaccess.c:16:
In file included from arch/s390/kvm/kvm-s390.h:17:
In file included from include/linux/kvm_host.h:19:
In file included from include/linux/msi.h:27:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:35:59: note: expanded from macro '__le32_to_cpu'
#define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
^
include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32'
#define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
^
In file included from arch/s390/kvm/gaccess.c:16:
In file included from arch/s390/kvm/kvm-s390.h:17:
In file included from include/linux/kvm_host.h:19:
In file included from include/linux/msi.h:27:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writeb(value, PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:692:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsb(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:700:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsw(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:708:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsl(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:717:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesb(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:726:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesw(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:735:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesl(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
>> arch/s390/kvm/gaccess.c:1217:9: error: call to undeclared function 'cmpxchg_user_key'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
ret = cmpxchg_user_key((u8 *)hva, &old, *old_addr, new, access_key);
^
arch/s390/kvm/gaccess.c:1217:9: note: did you mean 'copy_to_user_key'?
arch/s390/include/asm/uaccess.h:51:1: note: 'copy_to_user_key' declared here
copy_to_user_key(void __user *to, const void *from, unsigned long n, unsigned long key)
^
arch/s390/kvm/gaccess.c:1225:9: error: call to undeclared function 'cmpxchg_user_key'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
ret = cmpxchg_user_key((u16 *)hva, &old, *old_addr, new, access_key);
^
arch/s390/kvm/gaccess.c:1233:9: error: call to undeclared function 'cmpxchg_user_key'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
ret = cmpxchg_user_key((u32 *)hva, &old, *old_addr, new, access_key);
^
arch/s390/kvm/gaccess.c:1241:9: error: call to undeclared function 'cmpxchg_user_key'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
ret = cmpxchg_user_key((u64 *)hva, &old, *old_addr, new, access_key);
^
arch/s390/kvm/gaccess.c:1249:9: error: call to undeclared function 'cmpxchg_user_key'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
ret = cmpxchg_user_key((__uint128_t *)hva, &old, *old_addr, new, access_key);
^
12 warnings and 5 errors generated.

vim +/cmpxchg_user_key +1217 arch/s390/kvm/gaccess.c

1163
1164 /**
1165 * cmpxchg_guest_abs_with_key() - Perform cmpxchg on guest absolute address.
1166 * @kvm: Virtual machine instance.
1167 * @gpa: Absolute guest address of the location to be changed.
1168 * @len: Operand length of the cmpxchg, required: 1 <= len <= 16. Providing a
1169 * non power of two will result in failure.
1170 * @old_addr: Pointer to old value. If the location at @gpa contains this value,
1171 * the exchange will succeed. After calling cmpxchg_guest_abs_with_key()
1172 * *@old_addr contains the value at @gpa before the attempt to
1173 * exchange the value.
1174 * @new: The value to place at @gpa.
1175 * @access_key: The access key to use for the guest access.
1176 * @success: output value indicating if an exchange occurred.
1177 *
1178 * Atomically exchange the value at @gpa by @new, if it contains *@old.
1179 * Honors storage keys.
1180 *
1181 * Return: * 0: successful exchange
1182 * * a program interruption code indicating the reason cmpxchg could
1183 * not be attempted
1184 * * -EINVAL: address misaligned or len not power of two
1185 * * -EAGAIN: transient failure (len 1 or 2)
1186 * * -EOPNOTSUPP: read-only memslot (should never occur)
1187 */
1188 int cmpxchg_guest_abs_with_key(struct kvm *kvm, gpa_t gpa, int len,
1189 __uint128_t *old_addr, __uint128_t new,
1190 u8 access_key, bool *success)
1191 {
1192 gfn_t gfn = gpa >> PAGE_SHIFT;
1193 struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
1194 bool writable;
1195 hva_t hva;
1196 int ret;
1197
1198 if (!IS_ALIGNED(gpa, len))
1199 return -EINVAL;
1200
1201 hva = gfn_to_hva_memslot_prot(slot, gfn, &writable);
1202 if (kvm_is_error_hva(hva))
1203 return PGM_ADDRESSING;
1204 /*
1205 * Check if it's a read-only memslot, even though that cannot occur
1206 * since those are unsupported.
1207 * Don't try to actually handle that case.
1208 */
1209 if (!writable)
1210 return -EOPNOTSUPP;
1211
1212 hva += offset_in_page(gpa);
1213 switch (len) {
1214 case 1: {
1215 u8 old;
1216
> 1217 ret = cmpxchg_user_key((u8 *)hva, &old, *old_addr, new, access_key);
1218 *success = !ret && old == *old_addr;
1219 *old_addr = old;
1220 break;
1221 }
1222 case 2: {
1223 u16 old;
1224
1225 ret = cmpxchg_user_key((u16 *)hva, &old, *old_addr, new, access_key);
1226 *success = !ret && old == *old_addr;
1227 *old_addr = old;
1228 break;
1229 }
1230 case 4: {
1231 u32 old;
1232
1233 ret = cmpxchg_user_key((u32 *)hva, &old, *old_addr, new, access_key);
1234 *success = !ret && old == *old_addr;
1235 *old_addr = old;
1236 break;
1237 }
1238 case 8: {
1239 u64 old;
1240
1241 ret = cmpxchg_user_key((u64 *)hva, &old, *old_addr, new, access_key);
1242 *success = !ret && old == *old_addr;
1243 *old_addr = old;
1244 break;
1245 }
1246 case 16: {
1247 __uint128_t old;
1248
1249 ret = cmpxchg_user_key((__uint128_t *)hva, &old, *old_addr, new, access_key);
1250 *success = !ret && old == *old_addr;
1251 *old_addr = old;
1252 break;
1253 }
1254 default:
1255 return -EINVAL;
1256 }
1257 mark_page_dirty_in_slot(kvm, slot, gfn);
1258 /*
1259 * Assume that the fault is caused by protection, either key protection
1260 * or user page write protection.
1261 */
1262 if (ret == -EFAULT)
1263 ret = PGM_PROTECTION;
1264 return ret;
1265 }
1266

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