Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: 98b0bf02738004829d7e26d6cb47b2e469aaba86 ("selftests: kvm: Use a shorter encoding to clear RAX")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master


in testcase: kernel-selftests
with following parameters:

	group: kselftests-kvm
	ucode: 0xdc

test-description: The kernel contains a set of "self tests" under the tools/testing/selftests/ directory. These are intended to be small unit tests to exercise individual code paths in the kernel.
test-url: https://www.kernel.org/doc/Documentation/kselftest.txt


on test machine: 8 threads Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz with 16G memory

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):



If you fix the issue, kindly add following tag
Reported-by: kernel test robot <rong.a.chen@intel.com>



# selftests: kvm: debug_regs
# ==== Test Assertion Failure ====
#   x86_64/debug_regs.c:170: run->exit_reason == KVM_EXIT_DEBUG && run->debug.arch.exception == DB_VECTOR && run->debug.arch.pc == target_rip && run->debug.arch.dr6 == target_dr6
#   pid=10520 tid=10520 - Success
#      1	0x0000000000401702: main at debug_regs.c:162
#      2	0x00007fb081c1d09a: ?? ??:0
#      3	0x0000000000401889: _start at ??:?
#   SINGLE_STEP[0]: exit 4 exception 1 rip 0x401963 (should be 0x401964) dr6 0xffff4ff0 (should be 0xffff4ff0)
not ok 17 selftests: kvm: debug_regs # exit=254




To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
Rong Chen