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Date: Wed, 13 Jan 2016 15:22:58 -0800
Message-ID: <CA+8MBbJpFWdkwC-yvmDFdFuLrchv2-XhPd3fk8A_hqOOyzm5og@mail.gmail.com>
Subject: Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy()
From: Tony Luck <tony.luck@gmail.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>, Dan Williams <dan.j.williams@intel.com>,
        Andy Lutomirski <luto@amacapital.net>,
        linux-nvdimm <linux-nvdimm@ml01.01.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, Robert <elliott@hpe.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>, X86 ML <x86@kernel.org>
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On Mon, Jan 11, 2016 at 2:44 AM, Ingo Molnar <mingo@kernel.org> wrote:
> So such a synthetic CPUID bit would definitely be useful.
>
> Also, knowing whether a memcpy function is recoverable or not, should not be
> delegated to callers: there should be the regular memcpy APIs, plus new APIs that
> do everything they can to provide recoverable memory copies. Whether it's achieved
> via flag checking, a function pointer or code patching is an implementation detail
> that's not visible to drivers making use of the new facility.
>
> I'd go for the simplest, most robust solution initially, also perhaps with boot
> time messages to make sure users know which variant is used and now.

Are there some examples of synthetic CPUID bits?  I grepped around and
found a handful of places making ad hoc decisions based on sub-strings of
x86_model_id[] ... but didn't find any systematic approach.

-Tony