linux-kernel - Re: [PATCH] x86/sev: Apply RMP table fixups for kexec.

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Message-ID: <37321af9-aee4-4ba6-81ac-0df4cef38644@amd.com>
Date: Tue, 2 Apr 2024 13:41:05 -0500
From: "Kalra, Ashish" <ashish.kalra@....com>
To: Borislav Petkov <bp@...en8.de>
Cc: bp@...nel.org, thomas.lendacky@....com, linux-kernel@...r.kernel.org,
 linux-tip-commits@...r.kernel.org, michael.roth@....com, x86@...nel.org
Subject: Re: [PATCH] x86/sev: Apply RMP table fixups for kexec.

On 4/2/2024 12:45 PM, Borislav Petkov wrote:

> On Tue, Apr 02, 2024 at 12:11:03PM -0500, Kalra, Ashish wrote:
>>> And if you mean the reservation in the kernel page tables (directmap)
>>> then that will not help as kexec uses it's own identity mapped page
>>> tables.
> So how hard would it be to *always* reserve the chunk of memory at the
> 2M boundary where the RMP table starts and up to the 2M boundary where
> the RMP  table ends?
>
> In *every* kernel.

But, that's what the e820 table fixup is doing, it is reserving the 
chunk of memory at the 2M boundary where the RMP table starts and ends 
in the e820. Kexec is referring to the e820 table(s) for placing it's 
segments in memory for the kexec boot.

Thanks, Ashish

>
> By default.
>
> Thx.
>