linux-kernel - Re: [PATCH] x86/ioremap: Map EFI runtime services data as encrypted for SEV

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Message-ID: <20200310163738.GF29372@zn.tnic>
Date:   Tue, 10 Mar 2020 17:37:38 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Joerg Roedel <jroedel@...e.de>
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Bruce Rogers <brogers@...e.com>
Subject: Re: [PATCH] x86/ioremap: Map EFI runtime services data as encrypted
 for SEV

On Tue, Mar 10, 2020 at 02:03:21PM +0100, Joerg Roedel wrote:
> See the comment added in the patch, walk_mem_res() does not iterate over
> the resource which contains EFI_RUNTIME_SERVICES_DATA, so
> __ioremap_check_encrypted() will not be called on that resource.
> 
> walk_system_ram_range() might do the job, but calling it only for
> EFI_RUNTIME_SERVICES_DATA has some overhead.

Ok, then.

Let's wrap this in a new function which is called at the end of
__ioremap_check_mem() instead of trying to map EFI_RUNTIME_SERVICES_DATA
to IORES_DESC types and match the flags just so that we can preserve the
flow. And add a comment above it why we're doing this.

As you said on IRC, none of the IO resource ranges covers the
EFI_RUNTIME_SERVICES_DATA.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette