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SubjectRe: [PATCH v1 11/19] x86/sev-es: Convert to insn_decode()
Hi Borislav,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.10 next-20201223]
[cannot apply to tip/perf/core tip/x86/core luto/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]

url: https://github.com/0day-ci/linux/commits/Borislav-Petkov/x86-insn-Add-an-insn_decode-API/20201224-014846
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 614cb5894306cfa2c7d9b6168182876ff5948735
config: x86_64-randconfig-a016-20201223 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project cee1e7d14f4628d6174b33640d502bff3b54ae45)
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 x86_64 cross compiling tool for clang build
# apt-get install binutils-x86-64-linux-gnu
# https://github.com/0day-ci/linux/commit/9cc93591504c88c42ab10903fc69062fc1461ed0
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Borislav-Petkov/x86-insn-Add-an-insn_decode-API/20201224-014846
git checkout 9cc93591504c88c42ab10903fc69062fc1461ed0
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64

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/kernel/sev-es.c:258:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer, res))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/kernel/sev-es.c:272:6: note: uninitialized use occurs here
if (ret < 0)
^~~
arch/x86/kernel/sev-es.c:258:3: note: remove the 'if' if its condition is always true
if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer, res))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/kernel/sev-es.c:247:14: note: initialize the variable 'ret' to silence this warning
int res, ret;
^
= 0
1 warning generated.


vim +258 arch/x86/kernel/sev-es.c

f980f9c31a923e9 Joerg Roedel 2020-09-07 243
f980f9c31a923e9 Joerg Roedel 2020-09-07 244 static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
f980f9c31a923e9 Joerg Roedel 2020-09-07 245 {
f980f9c31a923e9 Joerg Roedel 2020-09-07 246 char buffer[MAX_INSN_SIZE];
9cc93591504c88c Borislav Petkov 2020-12-23 247 int res, ret;
f980f9c31a923e9 Joerg Roedel 2020-09-07 248
5e3427a7bc432ed Joerg Roedel 2020-09-07 249 if (user_mode(ctxt->regs)) {
5e3427a7bc432ed Joerg Roedel 2020-09-07 250 res = insn_fetch_from_user(ctxt->regs, buffer);
5e3427a7bc432ed Joerg Roedel 2020-09-07 251 if (!res) {
5e3427a7bc432ed Joerg Roedel 2020-09-07 252 ctxt->fi.vector = X86_TRAP_PF;
5e3427a7bc432ed Joerg Roedel 2020-09-07 253 ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
5e3427a7bc432ed Joerg Roedel 2020-09-07 254 ctxt->fi.cr2 = ctxt->regs->ip;
5e3427a7bc432ed Joerg Roedel 2020-09-07 255 return ES_EXCEPTION;
5e3427a7bc432ed Joerg Roedel 2020-09-07 256 }
5e3427a7bc432ed Joerg Roedel 2020-09-07 257
63d702bf108e3ad Borislav Petkov 2020-12-23 @258 if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer, res))
5e3427a7bc432ed Joerg Roedel 2020-09-07 259 return ES_DECODE_FAILED;
5e3427a7bc432ed Joerg Roedel 2020-09-07 260 } else {
f980f9c31a923e9 Joerg Roedel 2020-09-07 261 res = vc_fetch_insn_kernel(ctxt, buffer);
5e3427a7bc432ed Joerg Roedel 2020-09-07 262 if (res) {
f980f9c31a923e9 Joerg Roedel 2020-09-07 263 ctxt->fi.vector = X86_TRAP_PF;
5e3427a7bc432ed Joerg Roedel 2020-09-07 264 ctxt->fi.error_code = X86_PF_INSTR;
f980f9c31a923e9 Joerg Roedel 2020-09-07 265 ctxt->fi.cr2 = ctxt->regs->ip;
f980f9c31a923e9 Joerg Roedel 2020-09-07 266 return ES_EXCEPTION;
f980f9c31a923e9 Joerg Roedel 2020-09-07 267 }
f980f9c31a923e9 Joerg Roedel 2020-09-07 268
9cc93591504c88c Borislav Petkov 2020-12-23 269 ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE - res, INSN_MODE_64);
5e3427a7bc432ed Joerg Roedel 2020-09-07 270 }
f980f9c31a923e9 Joerg Roedel 2020-09-07 271
9cc93591504c88c Borislav Petkov 2020-12-23 272 if (ret < 0)
9cc93591504c88c Borislav Petkov 2020-12-23 273 return ES_DECODE_FAILED;
9cc93591504c88c Borislav Petkov 2020-12-23 274 else
9cc93591504c88c Borislav Petkov 2020-12-23 275 return ES_OK;
f980f9c31a923e9 Joerg Roedel 2020-09-07 276 }
f980f9c31a923e9 Joerg Roedel 2020-09-07 277

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