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

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Date:   Tue, 10 Mar 2020 11:25:00 +0100
From:   Joerg Roedel <jroedel@...e.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "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

Hi Tom,

On Tue, Feb 25, 2020 at 09:42:07AM -0600, Tom Lendacky wrote:
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 44e4beb4239f..382b6ca66820 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -135,6 +135,13 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
>  	memset(desc, 0, sizeof(struct ioremap_desc));
>  
>  	walk_mem_res(start, end, desc, __ioremap_collect_map_flags);
> +
> +	/*
> +	 * The EFI runtime services data area is not covered by walk_mem_res(),
> +	 * but must be mapped encrypted when SEV is active.
> +	 */
> +	if (sev_active() && efi_mem_type(addr) == EFI_RUNTIME_SERVICES_DATA)
> +		desc->flags |= IORES_MAP_ENCRYPTED;
>  }

I can confirm that this fixes dmi-decode on my SEV guest. While
reviewing I looked into using walk_system_ram_range(), but since this is
only for the EFI_RUNTIME_SERVICES_DATA, it is not needed, so:

Reviewed-by: Joerg Roedel <jroedel@...e.de>
Tested-by: Joerg Roedel <jroedel@...e.de>