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From: Tom Lendacky <thomas.lendacky@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "Joerg Roedel" <joro@8bytes.org>,
	linux-arch@vger.kernel.org, linux-efi@vger.kernel.org,
	kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	linux-mm@kvack.org, iommu@lists.linux-foundation.org,
	"Rik van Riel" <riel@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Matt Fleming" <matt@codeblueprint.co.uk>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Larry Woodman" <lwoodman@redhat.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Andrey Ryabinin" <aryabinin@virtuozzo.com>,
	"Alexander Potapenko" <glider@google.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Dmitry Vyukov" <dvyukov@google.com>
Subject: Re: [RFC PATCH v3 04/20] x86: Handle reduction in physical address size with SME
Date: Tue, 15 Nov 2016 10:06:16 -0600	[thread overview]
Message-ID: <bb47e943-f5b6-0d73-cf9a-fea002a5c70e@amd.com> (raw)
In-Reply-To: <20161115153338.a2cxmatnpqcgiaiy@pd.tnic>

On 11/15/2016 9:33 AM, Borislav Petkov wrote:
> On Tue, Nov 15, 2016 at 08:40:05AM -0600, Tom Lendacky wrote:
>> The feature may be present and enabled even if it is not currently
>> active.  In other words, the SYS_CFG MSR bit could be set but we aren't
>> actually using encryption (sme_me_mask is 0).  As long as the SYS_CFG
>> MSR bit is set we need to take into account the physical reduction in
>> address space.
> 
> But later in the series I see sme_early_mem_enc() which tests exactly
> that mask.

Yes, but that doesn't relate to the physical address space reduction.

Once the SYS_CFG MSR bit for SME is set, even if the encryption bit is
never used, there is a physical reduction of the address space. So when
checking whether to adjust the physical address bits I can't rely on the
sme_me_mask, I have to look at the MSR.

But when I'm looking to decide whether to encrypt or decrypt something,
I use the sme_me_mask to decide if that is needed.  If the sme_me_mask
is not set then the encrypt/decrypt op shouldn't be performed.

I might not be grasping the point you're trying to make...

Thanks,
Tom

> 
> And in patch 12 you have:
> 
> +       /*
> +        * If memory encryption is active, the trampoline area will need to
> +        * be in un-encrypted memory in order to bring up other processors
> +        * successfully.
> +        */
> +       sme_early_mem_dec(__pa(base), size);
> +       sme_set_mem_unenc(base, size);
> 
> What's up?
> 
> IOW, it all sounds to me like you want to have an sme_active() helper
> and use it everywhere.
> 

  reply	other threads:[~2016-11-15 16:06 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-10  0:34 [RFC PATCH v3 00/20] x86: Secure Memory Encryption (AMD) Tom Lendacky
2016-11-10  0:34 ` [RFC PATCH v3 01/20] x86: Documentation for AMD Secure Memory Encryption (SME) Tom Lendacky
2016-11-10 10:51   ` Borislav Petkov
2016-11-14 17:15     ` Tom Lendacky
2016-11-10  0:34 ` [RFC PATCH v3 02/20] x86: Set the write-protect cache mode for full PAT support Tom Lendacky
2016-11-10 13:14   ` Borislav Petkov
2016-11-11  1:26     ` Kani, Toshimitsu
2016-11-14 16:51       ` Tom Lendacky
2016-11-10  0:34 ` [RFC PATCH v3 03/20] x86: Add the Secure Memory Encryption cpu feature Tom Lendacky
2016-11-11 11:53   ` Borislav Petkov
2016-11-10  0:35 ` [RFC PATCH v3 04/20] x86: Handle reduction in physical address size with SME Tom Lendacky
2016-11-15 12:10   ` Joerg Roedel
2016-11-15 12:14     ` Borislav Petkov
2016-11-15 14:40       ` Tom Lendacky
2016-11-15 15:33         ` Borislav Petkov
2016-11-15 16:06           ` Tom Lendacky [this message]
2016-11-15 16:33             ` Borislav Petkov
2016-11-15 17:08               ` Tom Lendacky
2016-11-15 21:22       ` Tom Lendacky
2016-11-15 21:33         ` Borislav Petkov
2016-11-15 22:01           ` Tom Lendacky
2016-11-15 14:32     ` Tom Lendacky
2016-11-10  0:35 ` [RFC PATCH v3 05/20] x86: Add Secure Memory Encryption (SME) support Tom Lendacky
2016-11-10  0:35 ` [RFC PATCH v3 06/20] x86: Add support to enable SME during early boot processing Tom Lendacky
2016-11-14 17:29   ` Borislav Petkov
2016-11-14 18:18     ` Tom Lendacky
2016-11-14 20:01       ` Borislav Petkov
2016-11-10  0:35 ` [RFC PATCH v3 07/20] x86: Provide general kernel support for memory encryption Tom Lendacky
2016-11-10  0:36 ` [RFC PATCH v3 08/20] x86: Add support for early encryption/decryption of memory Tom Lendacky
2016-11-16 10:46   ` Borislav Petkov
2016-11-16 19:22     ` Tom Lendacky
2016-11-10  0:36 ` [RFC PATCH v3 09/20] x86: Insure that boot memory areas are mapped properly Tom Lendacky
2016-11-17 12:20   ` Borislav Petkov
2016-11-19 18:12     ` Tom Lendacky
2016-11-10  0:36 ` [RFC PATCH v3 10/20] Add support to access boot related data in the clear Tom Lendacky
2016-11-11 16:17   ` Kani, Toshimitsu
2016-11-14 16:24     ` Tom Lendacky
2016-11-17 15:55   ` Borislav Petkov
2016-11-19 18:33     ` Tom Lendacky
2016-11-20 23:04       ` Borislav Petkov
2016-12-07 13:19   ` Matt Fleming
2016-12-09 14:26     ` Tom Lendacky
2016-11-10  0:36 ` [RFC PATCH v3 11/20] x86: Add support for changing memory encryption attribute Tom Lendacky
2016-11-17 17:39   ` Borislav Petkov
2016-11-19 18:48     ` Tom Lendacky
2016-11-21  8:27       ` Borislav Petkov
2016-11-10  0:37 ` [RFC PATCH v3 12/20] x86: Decrypt trampoline area if memory encryption is active Tom Lendacky
2016-11-17 18:09   ` Borislav Petkov
2016-11-19 18:50     ` Tom Lendacky
2016-11-10  0:37 ` [RFC PATCH v3 13/20] x86: DMA support for memory encryption Tom Lendacky
2016-11-15 14:39   ` Radim Krčmář
2016-11-15 17:02     ` Tom Lendacky
2016-11-15 18:17       ` Radim Krčmář
2016-11-15 20:33         ` Tom Lendacky
2016-11-15 15:16   ` Michael S. Tsirkin
2016-11-15 18:29     ` Tom Lendacky
2016-11-15 19:16       ` Michael S. Tsirkin
2016-11-22 11:38       ` Borislav Petkov
2016-11-22 15:22         ` Michael S. Tsirkin
2016-11-22 15:41           ` Borislav Petkov
2016-11-22 20:41             ` Michael S. Tsirkin
2016-11-10  0:37 ` [RFC PATCH v3 14/20] iommu/amd: Disable AMD IOMMU if memory encryption is active Tom Lendacky
2016-11-14 16:32   ` Joerg Roedel
2016-11-14 16:48     ` Tom Lendacky
2016-11-10  0:37 ` [RFC PATCH v3 15/20] x86: Check for memory encryption on the APs Tom Lendacky
2016-11-22 19:25   ` Borislav Petkov
2016-11-29 18:00     ` Tom Lendacky
2016-11-10  0:37 ` [RFC PATCH v3 16/20] x86: Do not specify encrypted memory for video mappings Tom Lendacky
2016-11-10  0:38 ` [RFC PATCH v3 17/20] x86/kvm: Enable Secure Memory Encryption of nested page tables Tom Lendacky
2016-11-10  0:38 ` [RFC PATCH v3 18/20] x86: Access the setup data through debugfs un-encrypted Tom Lendacky
2016-11-10  0:38 ` [RFC PATCH v3 19/20] x86: Add support to make use of Secure Memory Encryption Tom Lendacky
2016-11-24 12:50   ` Borislav Petkov
2016-11-29 18:40     ` Tom Lendacky
2016-11-10  0:38 ` [RFC PATCH v3 20/20] " Tom Lendacky
2016-11-22 18:58   ` Borislav Petkov
2016-11-26 20:47   ` Borislav Petkov
2016-11-29 18:48     ` Tom Lendacky
2016-11-29 19:56       ` Borislav Petkov

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