linux-kernel - Re: [patch 6/6] x86/smp: Put CPUs into INIT on shutdown if possible

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sat, 3 Jun 2023 13:57:14 -0700
From:   Ashok Raj <ashok.raj@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     LKML <linux-kernel@...r.kernel.org>, <x86@...nel.org>,
        Ashok Raj <ashok.raj@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Tony Luck" <tony.luck@...el.com>,
        Arjan van de Veen <arjan@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [patch 6/6] x86/smp: Put CPUs into INIT on shutdown if possible

On Sat, Jun 03, 2023 at 10:07:04PM +0200, Thomas Gleixner wrote:
> Parking CPUs in a HLT loop is not completely safe vs. kexec() as HLT can
> resume execution due to NMI, SMI and MCE, which has the same issue as the
> MWAIT loop.
> 
> Kicking the secondary CPUs into INIT makes this safe against NMI and SMI.
> 
> A broadcast MCE will take the machine down, but a broadcast MCE which makes
> HLT resume and execute overwritten text, pagetables or data will end up in
> a disaster too.
> 
> So chose the lesser of two evils and kick the secondary CPUs into INIT
> unless the system has installed special wakeup mechanisms which are not
> using INIT.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

For the whole series.

Reviewed-by: Ashok Raj <ashok.raj@...el.com>