Message-ID: <522FA2A8.8080703@zytor.com>
Date: Tue, 10 Sep 2013 15:52:24 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Vivek Goyal <vgoyal@redhat.com>
CC: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org,
        kexec@lists.infradead.org, akpm@linux-foundation.org,
        zohar@linux.vnet.ibm.com, d.kasatkin@samsung.com,
        ebiederm@xmission.com, matthew.garrett@nebula.com,
        Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH 15/16] bootparam: Pass acpi_rsdp pointer in bootparam
References: <1378849471-10521-1-git-send-email-vgoyal@redhat.com> <1378849471-10521-16-git-send-email-vgoyal@redhat.com>
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On 09/10/2013 02:44 PM, Vivek Goyal wrote:
> Currently kexec does not enables EFI and its tables in second kernel. Hence
> acpi rsdp root pointer is passed on command line. But secureboot does not trust
> acpi_rsdp on command line as kernel can execute some of the code as retrieved
> by following acpi_rsdp and root can modify command line. So in secureboot
> mode we ignore acpi_rsdp on command line.
> 
> Start passing it in bootparams for the time being. kexec-tools will prepare
> the bootparams and put acpi_rsdp pointer there.
> 
> Peter Jones suggested that scan all ACPI memory for acpi_rsdp if EFI is
> not enabled. This probably is a better fix and most likely this patch will
> change and adopt that approach down the line.
> 
> In fact if we figure out how to make UEFI run time calls in second kernel,
> we will not need acpi_rsdp at all.
> 

Borislav Petkov has been working on a fixed mapping of UEFI memory,
which should allow UEFI runtime calls across kexec.

	-hpa


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