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Date: Fri, 8 Jan 2016 15:42:32 -0800
Message-ID: <CA+55aFxmc83LRHRSAsnydpqy4Y-K2V9RvRCU+dhV-kWzu2Gvpg@mail.gmail.com>
Subject: Re: [RFC 00/13] x86/mm: PCID and INVPCID
From: Linus Torvalds <torvalds@linux-foundation.org>
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To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>, the arch/x86 maintainers <x86@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>, Dave Hansen <dave.hansen@linux.intel.com>, Oleg Nesterov <oleg@redhat.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>

On Fri, Jan 8, 2016 at 3:36 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>>
>> Either things have changed (newer hardware with more pcids perhaps?)
>> or you did a better job at it.
>
> On my Skylake laptop, all of the PCID bits appear to have at least
> some effect.  Whether this means it gets hashed or whether this means
> that all of the bits are real, I don't know.

They have always gotten hashed, and no the bits aren't real - hardware
doesn't actually have as many bits in the pcid as there are in cr3.

              Linus

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