linux-kernel - Re: [RFC Part1 PATCH v3 05/17] x86, realmode: Don't decrypt trampoline area under SEV

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Message-ID: <c7f50d1e-4410-8ea2-d4d0-06de24a4c2e9@amd.com>
Date:   Thu, 10 Aug 2017 08:03:12 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...e.de>, Brijesh Singh <brijesh.singh@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-efi@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        kvm@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Piotr Luc <piotr.luc@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        David Howells <dhowells@...hat.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Laura Abbott <labbott@...hat.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Jonathan Corbet <corbet@....net>,
        Dave Airlie <airlied@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Arnd Bergmann <arnd@...db.de>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>
Subject: Re: [RFC Part1 PATCH v3 05/17] x86, realmode: Don't decrypt
 trampoline area under SEV

On 7/26/2017 11:03 AM, Borislav Petkov wrote:
>   Subject: x86/realmode: ...

Done.

> 
> On Mon, Jul 24, 2017 at 02:07:45PM -0500, Brijesh Singh wrote:
>> From: Tom Lendacky <thomas.lendacky@....com>
>>
>> When SEV is active the trampoline area will need to be in encrypted
>> memory so only mark the area decrypted if SME is active.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
>> ---
>>   arch/x86/realmode/init.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
>> index 1f71980..c7eeca7 100644
>> --- a/arch/x86/realmode/init.c
>> +++ b/arch/x86/realmode/init.c
>> @@ -63,9 +63,11 @@ static void __init setup_real_mode(void)
>>   	/*
>>   	 * If SME is active, the trampoline area will need to be in
>>   	 * decrypted memory in order to bring up other processors
>> -	 * successfully.
>> +	 * successfully. For SEV the trampoline area needs to be in
>> +	 * encrypted memory, so only do this for SME.
> 
> Or simply say:
> 
> "It is not needed for SEV."

Will do.

Thanks,
Tom

>