Re: Trying add smt=off disabled cores to cpupool crash xen

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 01/12/2023 7:59 pm, René Winther Højgaard wrote:
> If I set smt=off and try to configure cpupools with credit(1) as if
> all cores are available, I get the following crash.  
>
> The crash happens when I try to use xl cpupool-add-cpu on the disabled
> HT sibling cores.
>
> Hyper-threading is enabled in the firmware, and only disabled with
> smt=off.

CC'ing some maintainers.

I expect this will also explode when a CPU is runtime offlined with
`xen-hptool cpu-offline` and then added to a cpupool.

Interestingly, the crash is mov (%rdx,%rax,1),%r13, and I think that's
the percpu posion value in %rdx.

I expect cpupools want to reject parked/offline CPUs.

~Andrew

>
> Software: Xen-4.17.3 / Qubes OS 4.2.0-RC5
> Firmware: Dasharo 0.9.0 - Z790P
> Hardware: 13900K
>
> (XEN) ----[ Xen-4.17.3-pre  x86_64  debug=y  Not tainted ]----
> (XEN) CPU:    6
> (XEN) RIP:    e008:[<ffff82d040248f89>] schedule_cpu_add+0x50/0x456
> (XEN) RFLAGS: 0000000000010202   CONTEXT: hypervisor (d0v3)
> (XEN) rax: ffff82d0405a9288   rbx: ffff83107f5a1980   rcx:
> 0000000000000020
> (XEN) rdx: 80007d2fbfa59000   rsi: ffff83107f5a1980   rdi:
> 0000000000000020
> (XEN) rbp: 0000000000000009   rsp: ffff831087d3fc68   r8:
>  0000000000000000
> (XEN) r9:  ffff82d0405b6b60   r10: ffff831087d22ab0   r11:
> 0000000000000003
> (XEN) r12: ffff831087d22ab0   r13: 0000000000000020   r14:
> ffff831087d22ab0
> (XEN) r15: ffff82d0405ae680   cr0: 0000000080050033   cr4:
> 0000000000b526e0
> (XEN) cr3: 0000000912e30000   cr2: 000072e5cb008375
> (XEN) fsb: 000072e5caac7380   gsb: ffff8881b9d80000   gss:
> 0000000000000000
> (XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: e010   cs: e008
> (XEN) Xen code around <ffff82d040248f89> (schedule_cpu_add+0x50/0x456):
> (XEN)  db 8e 37 00 48 8b 14 ca <4c> 8b 2c 02 3b 3d 75 f0 1f 00 0f 83
> c9 01 00 00
> (XEN) Xen stack trace from rsp=ffff831087d3fc68:
> (XEN)    ffff83107f5a16e0 ffff82d040204c3b ffff831000000018
> ffff831087d3fd28
> (XEN)    ffff831087d3fcc8 3431831087d3fcd0 ffff83107f002033
> ffff831087d3fcd0
> (XEN)    0000000000000000 ffff831087d40d70 ffff82d040246d48
> 0000000000000000
> (XEN)    ffff83107f5a1980 0000000000000009 ffff831087d22ab0
> 0000000000000020
> (XEN)    ffff831087d22ab0 ffff82d0405ae680 ffff82d040235dec
> ffff831087d3fe20
> (XEN)    00000000ffffffed 0000000000000009 ffff83107f5a1980
> ffff82d040236b05
> (XEN)    0000000000000000 0000000000000000 000072e5cb098010
> ffff831087d3ffff
> (XEN)    0000000000000000 ffff82d04045d5d8 ffff82d040234763
> 00000000c0000102
> (XEN)    0000000000000000 0000000000000000 00000000c0000102
> 0000000d00000000
> (XEN)    ffffffff8101ede6 000000000000e033 0000000000011082
> ffffc90043c1fb00
> (XEN)    000000000000e02b 11e6f31d9b4cbeef 96994088d9fcbeef
> 7d897394f3ecbeef
> (XEN)    c501dd1632b4beef ffff82d040227cc6 ffff831087d3fe48
> 0000000000000000
> (XEN)    0000000000011082 0000000000000000 ffff831087d3ffff
> 0000000000000000
> (XEN)    ffffffff8101ede4 ffff82d0403495d0 0000001500000012
> 0000000200000004
> (XEN)    0000000000000000 0000000000000009 000072e5cad9cb60
> 7be382ddb0c16b00
> (XEN)    0000000000a97768 0000000000a97150 0000000000000000
> 00007ffe90589abc
> (XEN)    00007ffe9058a780 000000000043d990 000000000043d9b0
> 000072e5cad20434
> (XEN)    00007ffe90589ac0 000072e5cafa3f79 0000000000000008
> ffff831087d3fef8
> (XEN)    0000000000000023 ffff83107f52b000 0000000000000000
> 0000000000000000
> (XEN)    0000000000000000 ffff82d0402dd07f ffff83107f52b000
> 0000000000000000
> (XEN) Xen call trace:
> (XEN)    [<ffff82d040248f89>] R schedule_cpu_add+0x50/0x456
> (XEN)    [<ffff82d040204c3b>] S debugtrace_printk+0x119/0x2cc
> (XEN)    [<ffff82d040246d48>] S free_affinity_masks+0x15/0x17
> (XEN)    [<ffff82d040235dec>] S
> cpupool.c#cpupool_assign_cpu_locked+0x53/0x160
> (XEN)    [<ffff82d040236b05>] S cpupool_do_sysctl+0x367/0x760
> (XEN)    [<ffff82d040234763>] S do_sysctl+0x827/0x1269
> (XEN)    [<ffff82d040227cc6>] S timer.c#timer_lock+0x69/0x143
> (XEN)    [<ffff82d0403495d0>] S x86_emulate_wrapper+0x24/0x56
> (XEN)    [<ffff82d0402dd07f>] S pv_hypercall+0x3a2/0x4a9
> (XEN)    [<ffff82d0402012b7>] S lstar_enter+0x137/0x140
> (XEN)
> (XEN) debugtrace_dump() global buffer starting
> (XEN) wrap: 0
> (XEN) debugtrace_dump() global buffer finished
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 6:
> (XEN) GENERAL PROTECTION FAULT
> (XEN) [error_code=0000]
> (XEN) ****************************************
> (XEN)
> (XEN) Reboot in five seconds...
>
> /rene