Re: [PATCH v2 0/2] KVM: Fix race between reboot and hardware enabling

From: Marc Zyngier
Date: Thu May 18 2023 - 03:38:31 EST


On Sat, 13 May 2023 00:31:25 +0100,
Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>
> Fix a bug where enabling hardware virtualization can race with a forced
> reboot, e.g. `reboot -f`, and result in virt hardware being enabled when
> the reboot is attempted, and thus hanging the reboot.
>
> Found by inspection, confirmed by hacking the reboot flow to wait until
> KVM loads (the problematic window is ridiculously small).
>
> Fully tested only on x86, compile tested on other architectures.
>
> v2:
> - Rename KVM's callback to kvm_shutdown() to match the hook. [Marc]
> - Don't add a spurious newline. [Marc]
>
> v1: https://lore.kernel.org/all/20230310221414.811690-1-seanjc@xxxxxxxxxx
>
> Sean Christopherson (2):
> KVM: Use syscore_ops instead of reboot_notifier to hook
> restart/shutdown
> KVM: Don't enable hardware after a restart/shutdown is initiated
>
> virt/kvm/kvm_main.c | 43 +++++++++++++++++++++++++++----------------
> 1 file changed, 27 insertions(+), 16 deletions(-)

Acked-by: Marc Zyngier <maz@xxxxxxxxxx>

M.

--
Without deviation from the norm, progress is not possible.