Re: [PATCH v4 0/4] x86/crash: Fix double NMI shootdown bug

Guilherme G. Piccoli
2023-01-28T14:53:30Z

On 27/01/2023 21:05, Sean Christopherson wrote:
> On Wed, 30 Nov 2022 23:36:46 +0000, Sean Christopherson wrote:
>> Fix a double NMI shootdown bug found and debugged by Guilherme, who did all
>> the hard work. NMI shootdown is a one-time thing; the handler leaves NMIs
>> blocked and enters halt. At best, a second (or third...) shootdown is an
>> expensive nop, at worst it can hang the kernel and prevent kexec'ing into
>> a new kernel, e.g. prior to the hardening of register_nmi_handler(), a
>> double shootdown resulted in a double list_add(), which is fatal when running
>> with CONFIG_BUG_ON_DATA_CORRUPTION=y.
>>
>> [...]
>
> Applied to kvm-x86 misc, thanks!
>
> [1/4] x86/crash: Disable virt in core NMI crash handler to avoid double shootdown
> https://github.com/kvm-x86/linux/commit/26044aff37a5
> [2/4] x86/virt: Force GIF=1 prior to disabling SVM (for reboot flows)
> https://github.com/kvm-x86/linux/commit/6a3236580b0b
> [3/4] x86/reboot: Disable virtualization in an emergency if SVM is supported
> https://github.com/kvm-x86/linux/commit/d81f952aa657
> [4/4] x86/reboot: Disable SVM, not just VMX, when stopping CPUs
> https://github.com/kvm-x86/linux/commit/a2b07fa7b933
>
> --
> https://github.com/kvm-x86/linux/tree/next
> https://github.com/kvm-x86/linux/tree/fixes

Thanks a bunch Sean!