breakpoint setting in nt!KiSystemCall64 not working - windows

Question

I want having a deep dive into ntdll!NtQueueApcThread seeing what happen after syscall instruction is executed. According to the document(Intel® 64 and IA-32 Architectures Software Developer’s Manual), the syscall instruction using the msr's LSTAR (0xC0000082) as the rip, so I set breakpoint in the nt!KiSystemCall64, which is the address I got by "rdmsr c0000082". But it's not working, my debugger doesn't break. It seems that the syscall inst does not jump to the address stored in the msr.
This is what I have done:
0: kd>
ntdll!NtQueueApcThread+0x10:
0033:00007ffb`3c32c640 7503 jne ntdll!NtQueueApcThread+0x15 (00007ffb`3c32c645)
0: kd>
ntdll!NtQueueApcThread+0x12:
0033:00007ffb`3c32c642 0f05 syscall
0: kd> rdmsr c0000082
msr[c0000082] = fffff802`3681e6c0
0: kd> u fffff802`3681e6c0
nt!KiSystemCall64:
fffff802`3681e6c0 0f01f8 swapgs
fffff802`3681e6c3 654889242510000000 mov qword ptr gs:[10h],rsp
fffff802`3681e6cc 65488b2425a8010000 mov rsp,qword ptr gs:[1A8h]
fffff802`3681e6d5 6a2b push 2Bh
fffff802`3681e6d7 65ff342510000000 push qword ptr gs:[10h]
fffff802`3681e6df 4153 push r11
fffff802`3681e6e1 6a33 push 33h
fffff802`3681e6e3 51 push rcx
0: kd> bp ffff802`3681e6c0
0: kd> t
ntdll!NtQueueApcThread+0x14:
0033:00007ffb`3c32c644 c3 ret
the target system version is Windows10 build 19042

Answer 1

After a few day study, I got to know what the problem is. In normal situation, setting a breakpoint in nt!KiSystemCall64 will cause a BSOD, this is because the first three instruction in nt!KiSystemCall64 is setting the kernel stack, which is required by windows kernel debugging mechanism. So the solution is setting the breakoint after the kernel stack is setup
bp nt!KiSystemCall64+0x15
In my situation, setting breakpoint does nothing happend, seems like the breakpoint is not working, I guess it is due to the anti-virus software I installed, which may have hooked some thing. After I uninstalled it, breakpoint is worked.