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Date: Thu, 18 May 2017 20:50:51 +0100
From: Matt Fleming <matt@codeblueprint.co.uk>
To: Borislav Petkov <bp@alien8.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>, linux-arch@vger.kernel.org,
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Subject: Re: [PATCH v5 17/32] x86/mm: Add support to access boot related data
 in the clear
Message-ID: <20170518195051.GA5651@codeblueprint.co.uk>
References: <20170418211612.10190.82788.stgit@tlendack-t1.amdoffice.net>
 <20170418211921.10190.1537.stgit@tlendack-t1.amdoffice.net>
 <20170515183517.mb4k2gp2qobbuvtm@pd.tnic>
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On Mon, 15 May, at 08:35:17PM, Borislav Petkov wrote:
> On Tue, Apr 18, 2017 at 04:19:21PM -0500, Tom Lendacky wrote:
>
> > +		paddr = boot_params.efi_info.efi_memmap_hi;
> > +		paddr <<= 32;
> > +		paddr |= boot_params.efi_info.efi_memmap;
> > +		if (phys_addr == paddr)
> > +			return true;
> > +
> > +		paddr = boot_params.efi_info.efi_systab_hi;
> > +		paddr <<= 32;
> > +		paddr |= boot_params.efi_info.efi_systab;
> 
> So those two above look like could be two global vars which are
> initialized somewhere in the EFI init path:
> 
> efi_memmap_phys and efi_systab_phys or so.
> 
> Matt ?
> 
> And then you won't need to create that paddr each time on the fly. I
> mean, it's not a lot of instructions but still...
 
We should already have the physical memmap address available in
'efi.memmap.phys_map'.

And the physical address of the system table should be in
'efi_phys.systab'. See efi_init().