linux-kernel - Re: [patch 1/2 v2] x86/cpu: Init AP exception handling from cpu_init

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Date:   Wed, 12 May 2021 10:37:37 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Lai Jiangshan <laijs@...ux.alibaba.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...e.de>
Subject: Re: [patch 1/2 v2] x86/cpu: Init AP exception handling from
 cpu_init_secondary()

On Tue, May 11, 2021 at 05:25:35PM +0800, Lai Jiangshan wrote:
> 
> 
> On 2021/5/11 05:29, Thomas Gleixner wrote:
> > From: Borislav Petkov <bp@...e.de>
> > 
> > SEV-ES guests require properly setup task register with which the TSS
> > descriptor in the GDT can be located so that the IST-type #VC exception
> > handler which they need to function properly, can be executed.
> > 
> > This setup needs to happen before attempting to load microcode in
> > ucode_cpu_init() on secondary CPUs which can cause such #VC exceptions.
> > 
> > Simplify the machinery by running that exception setup from a new function
> > cpu_init_secondary() and explicitly call cpu_init_exception_handling() for
> > the boot CPU before cpu_init(). The latter prepares for fixing and
> > simplifying the exception/IST setup on the boot CPU.
> > 
> > There should be no functional changes resulting from this patch.
> > 
> > [ tglx: Reworked it so cpu_init_exception_handling() stays seperate ]
> > 
> > Signed-off-by: Borislav Petkov <bp@...e.de>
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> 
> 
> For both patches:
> 
> Reviewed-by: Lai Jiangshan <laijs@...ux.alibaba.com>

Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>