Re: [PATCH v3 0/9] Parallel CPU bringup for x86_64

[Tom Lendacky]

On 12/17/21 2:13 PM, David Woodhouse wrote:
> On Fri, 2021-12-17 at 13:46 -0600, Tom Lendacky wrote:
> > There's no WARN or PANIC, just a reset. I can look to try and capture some
> > KVM trace data if that would help. If so, let me know what events you'd
> > like captured.
>
>
> Could start with just kvm_run_exit?
>
> Reason 8 would be KVM_EXIT_SHUTDOWN and would potentially indicate a
> triple fault.

qemu-system-x86-24093   [005] .....  1601.759486: kvm_exit: vcpu 112 reason shutdown rip 0xffffffff81070574 info1 0x0000000000000000 info2 0x0000000000000000 intr_info 0x80000b08 error_code 0x00000000

# addr2line -e woodhouse-build-x86_64/vmlinux 0xffffffff81070574
/root/kernels/woodhouse-build-x86_64/./arch/x86/include/asm/desc.h:272

Which is: asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));

Thanks,
Tom

> Failing that, I'd want to start littering the real mode code with
> outputting 'a' 'b' 'c' etc. to the serial port and see if the offending
> CPU is really in the trampoline somewhere when something goes wrong.
>
> I can knock up an example patch to do that (not tonight) but this would
> be somewhat easier if I could find a machine I can reproduce on. Sadly
> I only seem to have access to Milan *guests* without nested virt, not
> bare metal. Got a machine I can log in to?
>
>