linux-kernel - Re: [PATCH v4 4/4] x86/reboot: Disable SVM, not just VMX, when stopping CPUs

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Message-ID: <Y4fpkUUeu0s86Sh4@google.com>
Date:   Wed, 30 Nov 2022 23:38:57 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        "Guilherme G . Piccoli" <gpiccoli@...lia.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [PATCH v4 4/4] x86/reboot: Disable SVM, not just VMX, when
 stopping CPUs

On Wed, Nov 30, 2022, Sean Christopherson wrote:
> Disable SVM and more importantly force GIF=1 when halting a CPU or
> rebooting the machine.  Similar to VMX, SVM allows software to block
> INITs via CLGI, and thus can be problematic for a crash/reboot.  The
> window for failure is smaller with SVM as INIT is only blocked while
> GIF=0, i.e. between CLGI and STGI, but the window does exist.
> 
> Fixes: fba4f472b33a ("x86/reboot: Turn off KVM when halting a CPU")
> Cc: stable@...r.kernel

Argh, forgot the .org, and of course my scripts then failed to filter out the
address.