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

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Date:   Tue, 8 Sep 2020 15:07:05 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
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

> 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.

We can even get a nice diagnostic message since the handler
has access to "regs". It can print which MSR (regs->cx) and
where it happened (regs->ip).

Which sounds like you might want a specific ex_handler_rdmsr
function rather than a generic ex_handler_panic.

Maybe same deal for wrmsr() too? That would also print edx:eax
so you could see what was being written.

-Tony