Re: [PATCH RFC 3/5] powerpc/speculation: Add support for 'cpu_spec_mitigations=' cmdline options

Timothy Pearson
2019-04-04T20:01:04Z

Will be joining in ~ 5 mins. Getting Chromium set up here.

----- Original Message -----
> From: "Jiri Kosina" <jikos@kernel.org>
> To: "Josh Poimboeuf" <jpoimboe@redhat.com>
> Cc: "Peter Zijlstra" <peterz@infradead.org>, "Heiko Carstens" <heiko.carstens@de.ibm.com>, "Paul Mackerras"
> <paulus@samba.org>, "H . Peter Anvin" <hpa@zytor.com>, "Ingo Molnar" <mingo@kernel.org>, "Andrea Arcangeli"
> <aarcange@redhat.com>, linux-s390@vger.kernel.org, x86@kernel.org, "Will Deacon" <will.deacon@arm.com>, "Linus
> Torvalds" <torvalds@linux-foundation.org>, "Catalin Marinas" <catalin.marinas@arm.com>, "Waiman Long"
> <longman@redhat.com>, linux-arch@vger.kernel.org, "Jon Masters" <jcm@redhat.com>, "Borislav Petkov" <bp@alien8.de>,
> "Andy Lutomirski" <luto@kernel.org>, "Thomas Gleixner" <tglx@linutronix.de>, linux-arm-kernel@lists.infradead.org,
> "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>, linux-kernel@vger.kernel.org, "Tyler Hicks" <tyhicks@canonical.com>,
> "Martin Schwidefsky" <schwidefsky@de.ibm.com>, linuxppc-dev@lists.ozlabs.org
> Sent: Thursday, April 4, 2019 2:49:05 PM
> Subject: Re: [PATCH RFC 3/5] powerpc/speculation: Add support for 'cpu_spec_mitigations=' cmdline options

> On Thu, 4 Apr 2019, Josh Poimboeuf wrote:
>
>> Configure powerpc CPU runtime speculation bug mitigations in accordance
>> with the 'cpu_spec_mitigations=' cmdline options. This affects
>> Meltdown, Spectre v1, Spectre v2, and Speculative Store Bypass.
> [ ... snip ... ]
>> - if (!no_nospec)
>> + if (!no_nospec && cpu_spec_mitigations != CPU_SPEC_MITIGATIONS_OFF)
>
> '!no_nospec' is something that I am sure will come back to hunt me in my
> bad dreams.
>
> But that's been there already, and fixing it is out of scope of this
> patch. Other than that, as discussed previously -- I really like this new
> global option. Feel free to add
>
> Reviewed-by: Jiri Kosina <jkosina@suse.cz>
>
> for the whole set.
>
> Thanks,
>
> --
> Jiri Kosina
> SUSE Labs