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Message-ID: <616644bb-6a38-e480-3375-bd39a8487b7d@amd.com>
Date: Wed, 7 Sep 2016 09:11:35 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Borislav Petkov <bp@...en8.de>
CC: <linux-arch@...r.kernel.org>, <linux-efi@...r.kernel.org>,
<kvm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<x86@...nel.org>, <linux-kernel@...r.kernel.org>,
<kasan-dev@...glegroups.com>, <linux-mm@...ck.org>,
<iommu@...ts.linux-foundation.org>,
Radim Krčmář <rkrcmar@...hat.com>,
Arnd Bergmann <arnd@...db.de>,
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Matt Fleming <matt@...eblueprint.co.uk>,
Joerg Roedel <joro@...tes.org>,
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Andrey Ryabinin <aryabinin@...tuozzo.com>,
Ingo Molnar <mingo@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
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Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [RFC PATCH v2 07/20] x86: Provide general kernel support for
memory encryption
On 09/02/2016 01:14 PM, Borislav Petkov wrote:
> On Mon, Aug 22, 2016 at 05:36:46PM -0500, Tom Lendacky wrote:
>> Adding general kernel support for memory encryption includes:
>> - Modify and create some page table macros to include the Secure Memory
>> Encryption (SME) memory encryption mask
>> - Update kernel boot support to call an SME routine that checks for and
>> sets the SME capability (the SME routine will grow later and for now
>> is just a stub routine)
>> - Update kernel boot support to call an SME routine that encrypts the
>> kernel (the SME routine will grow later and for now is just a stub
>> routine)
>> - Provide an SME initialization routine to update the protection map with
>> the memory encryption mask so that it is used by default
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> ---
>
> ...
>
>> diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
>> index 747fc52..9f3e762 100644
>> --- a/arch/x86/include/asm/mem_encrypt.h
>> +++ b/arch/x86/include/asm/mem_encrypt.h
>> @@ -15,12 +15,21 @@
>>
>> #ifndef __ASSEMBLY__
>>
>> +#include <linux/init.h>
>> +
>> #ifdef CONFIG_AMD_MEM_ENCRYPT
>>
>> extern unsigned long sme_me_mask;
>>
>> u8 sme_get_me_loss(void);
>>
>> +void __init sme_early_init(void);
>> +
>> +#define __sme_pa(x) (__pa((x)) | sme_me_mask)
>> +#define __sme_pa_nodebug(x) (__pa_nodebug((x)) | sme_me_mask)
>> +
>> +#define __sme_va(x) (__va((x) & ~sme_me_mask))
>
> So I'm wondering: why not push the masking off of the SME mask into the
> __va() macro instead of defining a specific __sme_va() one?
>
> I mean, do you even see cases where __va() would need to have to
> sme_mask left in the virtual address?
>
> Because if not, you could mask it out in __va() so that all __va() users
> get the "clean" va, without the enc bits.
That's a good point, yes, it could go in __va(). I'll make that change.
>
> Hmmm.
>
> Btw, this patch is huuuge. It would be nice if you could split it, if
> possible...
Ok, I'll look at how to make this a bit more manageable.
Thanks,
Tom
>
> Thanks.
>
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