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

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Date:   Fri, 12 May 2023 16:31:25 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Marc Zyngier <maz@...nel.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,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH v2 0/2] KVM: Fix race between reboot and hardware enabling

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(-)


base-commit: b3c98052d46948a8d65d2778c7f306ff38366aac
-- 
2.40.1.606.ga4b1b128d6-goog