Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy()

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy()
Date	2016-01-11 11:50 +0100
Message-ID	<qPIcX-17S-33@gated-at.bofh.it> (permalink)
References	(5 earlier) <qPa1B-3rw-9@gated-at.bofh.it> <qPakW-3yt-15@gated-at.bofh.it> <qPc3o-4Mp-1@gated-at.bofh.it> <qPdiO-5Bj-3@gated-at.bofh.it> <qPmm6-3uu-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

* Borislav Petkov <bp@alien8.de> wrote:

> On Sat, Jan 09, 2016 at 05:40:05PM -0800, Tony Luck wrote:
> > BUT ... it's all going to be very messy.  We don't have any CPUID
> > capability bits to say whether we support recovery, or which instructions
> > are good/bad choices for recovery.
> 
> We can always define synthetic ones and set them after having checked
> MCA capability bits, f/m/s, etc., maybe even based on the list you're
> supplying...

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.

Thanks,

	Ingo

Thread

[PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Tony Luck <tony.luck@intel.com> - 2016-01-09 01:20 +0100
  Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Andy Lutomirski <luto@amacapital.net> - 2016-01-09 02:50 +0100
    Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Tony Luck <tony.luck@gmail.com> - 2016-01-09 18:50 +0100
      Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Andy Lutomirski <luto@amacapital.net> - 2016-01-09 19:00 +0100
        Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Tony Luck <tony.luck@gmail.com> - 2016-01-09 20:50 +0100
          Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Dan Williams <dan.j.williams@intel.com> - 2016-01-09 23:20 +0100
            Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Andy Lutomirski <luto@amacapital.net> - 2016-01-09 23:40 +0100
              Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Dan Williams <dan.j.williams@intel.com> - 2016-01-10 01:30 +0100
                Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Tony Luck <tony.luck@gmail.com> - 2016-01-10 02:50 +0100
                Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Borislav Petkov <bp@alien8.de> - 2016-01-10 12:30 +0100
                Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Ingo Molnar <mingo@kernel.org> - 2016-01-11 11:50 +0100
                Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Tony Luck <tony.luck@gmail.com> - 2016-01-14 00:30 +0100
                Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Borislav Petkov <bp@alien8.de> - 2016-01-14 05:50 +0100
    Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() "Luck, Tony" <tony.luck@intel.com> - 2016-01-12 01:30 +0100
      Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Andy Lutomirski <luto@amacapital.net> - 2016-01-12 01:40 +0100
      Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy() Andy Lutomirski <luto@amacapital.net> - 2016-01-12 01:40 +0100

csiph-web