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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Sat, 22 Dec 2018 12:07:48 +0100
Message-ID: <CAKv+Gu-v+nBh2yK0uXbuwwnpEnpG8bk4ufSMXygMOdOd2XSTYw@mail.gmail.com>
Subject: Re: [tip:efi/core] x86/efi: Unmap EFI boot services code/data regions
 from efi_pgd
To:     Borislav Petkov <bp@alien8.de>
Cc:     Matt Fleming <matt@codeblueprint.co.uk>,
        "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@intel.com>,
        Ingo Molnar <mingo@kernel.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "x86@kernel.org" <x86@kernel.org>,
        "marc.zyngier@arm.com" <marc.zyngier@arm.com>,
        "eric.snowberg@oracle.com" <eric.snowberg@oracle.com>,
        "hdegoede@redhat.com" <hdegoede@redhat.com>,
        "Hansen, Dave" <dave.hansen@intel.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "hpa@zytor.com" <hpa@zytor.com>,
        "arend.vanspriel@broadcom.com" <arend.vanspriel@broadcom.com>,
        "julien.thierry@arm.com" <julien.thierry@arm.com>,
        "bhsharma@redhat.com" <bhsharma@redhat.com>,
        "jonathanh@nvidia.com" <jonathanh@nvidia.com>,
        "joe@perches.com" <joe@perches.com>,
        "torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
        "natechancellor@gmail.com" <natechancellor@gmail.com>,
        "luto@kernel.org" <luto@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "sedat.dilek@gmail.com" <sedat.dilek@gmail.com>,
        "zhuyifei1999@gmail.com" <zhuyifei1999@gmail.com>,
        "linux-tip-commits@vger.kernel.org" 
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On Fri, 21 Dec 2018 at 20:29, Borislav Petkov <bp@alien8.de> wrote:
>
> On Fri, Dec 21, 2018 at 06:26:23PM +0100, Ard Biesheuvel wrote:
> > On Fri, 21 Dec 2018 at 18:13, Borislav Petkov <bp@alien8.de> wrote:
> > >
> > > On Fri, Dec 21, 2018 at 06:02:29PM +0100, Ard Biesheuvel wrote:
> > > > As far as I can tell, the SGI x86 UV platforms still rely on this, so
> > > > we're stuck with it for the foreseeable future.
> > >
> > > What happened with the old apple laptops which couldn't handle high
> > > virtual mappings and needed 1:1? We don't care anymore?
> > >
> >
> > If that is the case (I wouldn't know) then yes, there is a second
> > reason why we need to keep this code.
>
> Fleming knows details and he's on CC, lemme "pull" him up into To: :-)
>

IIUC the 1:1 mapping and the 'old' mapping are two different things,
and the new mapping also contains a 1:1 mapping of the boot services
regions, at least until SetVirtualAddressMap() returns.