linux-kernel - Re: [RFC PATCH] x86/mce: Make mce

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Message-ID: <20200908100837.GC25236@zn.tnic>
Date:   Tue, 8 Sep 2020 12:08:37 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     x86-ml <x86@...nel.org>, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] x86/mce: Make mce_rdmsrl() do a plain RDMSR only

On Tue, Sep 08, 2020 at 11:46:50AM +0200, Borislav Petkov wrote:
> So, Andy suggested we do a simple .fixup so that when the RDMSR fails,
> in the fixup we panic directly.

Ok, so I think this is what Andy meant last night and PeterZ just
suggested it too:

We do a:

	 _ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_panic)

which panics straight in the #GP handler and avoids the IRET.

I mean, we want to panic there because architectural violation and we
won't have to deal with the IRET...

Hohumm, sounds like the right thing to do in the face of the brokenness
of this magnificent architecture.</maxed out sarcasm>.

-- 
Regards/Gruss,
    Boris.

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