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

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Date:   Thu, 18 May 2023 08:38:20 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Oliver Upton <oliver.upton@...ux.dev>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>, kvmarm@...ts.linux.dev,
        Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        kvm-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 0/2] KVM: Fix race between reboot and hardware enabling

On Sat, 13 May 2023 00:31:25 +0100,
Sean Christopherson <seanjc@...gle.com> 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@google.com
> 
> 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@...nel.org>

	M.

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