From: Tom Lendacky <thomas.lendacky@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: 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,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Jonathan Corbet" <corbet@lwn.net>,
"Matt Fleming" <matt@codeblueprint.co.uk>,
"Joerg Roedel" <joro@8bytes.org>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Andrey Ryabinin" <aryabinin@virtuozzo.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Andy Lutomirski" <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Alexander Potapenko" <glider@google.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Dmitry Vyukov" <dvyukov@google.com>
Subject: Re: [RFC PATCH v2 16/20] x86: Check for memory encryption on the APs
Date: Wed, 14 Sep 2016 08:50:25 -0500 [thread overview]
Message-ID: <06a97eaa-d54f-9f7e-d207-4ff3e576169f@amd.com> (raw)
In-Reply-To: <20160912121739.rwuumwpwo5megmd7@pd.tnic>
On 09/12/2016 07:17 AM, Borislav Petkov wrote:
> On Mon, Aug 22, 2016 at 05:38:29PM -0500, Tom Lendacky wrote:
>> Add support to check if memory encryption is active in the kernel and that
>> it has been enabled on the AP. If memory encryption is active in the kernel
>> but has not been enabled on the AP then do not allow the AP to continue
>> start up.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>> ---
>> arch/x86/include/asm/msr-index.h | 2 ++
>> arch/x86/include/asm/realmode.h | 12 ++++++++++++
>> arch/x86/realmode/init.c | 4 ++++
>> arch/x86/realmode/rm/trampoline_64.S | 19 +++++++++++++++++++
>> 4 files changed, 37 insertions(+)
>
> ...
>
>> diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
>> index dac7b20..94e29f4 100644
>> --- a/arch/x86/realmode/rm/trampoline_64.S
>> +++ b/arch/x86/realmode/rm/trampoline_64.S
>> @@ -30,6 +30,7 @@
>> #include <asm/msr.h>
>> #include <asm/segment.h>
>> #include <asm/processor-flags.h>
>> +#include <asm/realmode.h>
>> #include "realmode.h"
>>
>> .text
>> @@ -92,6 +93,23 @@ ENTRY(startup_32)
>> movl %edx, %fs
>> movl %edx, %gs
>>
>> + /* Check for memory encryption support */
>> + bt $TH_FLAGS_SME_ENABLE_BIT, pa_tr_flags
>> + jnc .Ldone
>> + movl $MSR_K8_SYSCFG, %ecx
>> + rdmsr
>> + bt $MSR_K8_SYSCFG_MEM_ENCRYPT_BIT, %eax
>> + jc .Ldone
>> +
>> + /*
>> + * Memory encryption is enabled but the MSR has not been set on this
>> + * CPU so we can't continue
>
> Hmm, let me try to parse this correctly: BSP has SME enabled but the
> BIOS might not've set this on the AP? Really? Is that even possible?
Anything is possible, although it's highly unlikely.
>
> Because if SME is enabled, that means that MSR_K8_SYSCFG[23] on the BSP
> is set, right?
Correct.
>
> Also, I want to rule out here simple BIOS idiocy: if the only problem
> with the bit not being set in the AP is because some BIOS monkey forgot
> to do so, then we should try to set it ourselves and not die for no real
> reason.
Yes, we can do that. I was debating on which way to go with this. Most
likely this would never happen, but if it did... I can change this to
set the MSR bit and continue.
Thanks,
Tom
>
> Or is there another issue?
>
next prev parent reply other threads:[~2016-09-14 13:50 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-22 22:35 [RFC PATCH v2 00/20] x86: Secure Memory Encryption (AMD) Tom Lendacky
2016-08-22 22:35 ` [RFC PATCH v2 01/20] x86: Documentation for AMD Secure Memory Encryption (SME) Tom Lendacky
2016-09-02 8:50 ` Borislav Petkov
2016-09-07 14:02 ` Tom Lendacky
2016-09-07 15:23 ` Borislav Petkov
2016-08-22 22:35 ` [RFC PATCH v2 02/20] x86: Set the write-protect cache mode for full PAT support Tom Lendacky
2016-08-25 3:58 ` Borislav Petkov
2016-08-22 22:35 ` [RFC PATCH v2 03/20] x86: Secure Memory Encryption (SME) build enablement Tom Lendacky
2016-09-02 11:03 ` Borislav Petkov
2016-09-07 14:03 ` Tom Lendacky
2016-08-22 22:36 ` [RFC PATCH v2 04/20] x86: Secure Memory Encryption (SME) support Tom Lendacky
2016-08-25 13:04 ` Thomas Gleixner
2016-08-30 13:19 ` Tom Lendacky
2016-08-30 14:57 ` Andy Lutomirski
2016-08-31 13:26 ` Tom Lendacky
2016-08-22 22:36 ` [RFC PATCH v2 05/20] x86: Add the Secure Memory Encryption cpu feature Tom Lendacky
2016-09-02 14:09 ` Borislav Petkov
2016-09-07 14:07 ` Tom Lendacky
2016-08-22 22:36 ` [RFC PATCH v2 06/20] x86: Handle reduction in physical address size with SME Tom Lendacky
2016-08-22 22:36 ` [RFC PATCH v2 07/20] x86: Provide general kernel support for memory encryption Tom Lendacky
2016-09-02 18:14 ` Borislav Petkov
2016-09-07 14:11 ` Tom Lendacky
2016-09-05 8:48 ` Borislav Petkov
2016-09-07 14:16 ` Tom Lendacky
2016-09-05 15:22 ` Borislav Petkov
2016-09-07 14:19 ` Tom Lendacky
2016-09-06 9:31 ` Borislav Petkov
2016-09-07 14:30 ` Tom Lendacky
2016-09-07 15:55 ` Borislav Petkov
2016-09-08 13:26 ` Tom Lendacky
2016-09-08 13:55 ` Borislav Petkov
2016-09-12 13:43 ` Tom Lendacky
2016-08-22 22:37 ` [RFC PATCH v2 08/20] x86: Extend the early_memmap support with additional attrs Tom Lendacky
2016-08-22 22:37 ` [RFC PATCH v2 09/20] x86: Add support for early encryption/decryption of memory Tom Lendacky
2016-09-06 16:12 ` Borislav Petkov
2016-08-22 22:37 ` [RFC PATCH v2 10/20] x86: Insure that memory areas are encrypted when possible Tom Lendacky
2016-09-09 15:53 ` Borislav Petkov
2016-09-12 15:05 ` Tom Lendacky
2016-09-12 16:33 ` Borislav Petkov
2016-09-14 14:11 ` Tom Lendacky
2016-08-22 22:37 ` [RFC PATCH v2 11/20] mm: Access BOOT related data in the clear Tom Lendacky
2016-09-09 16:38 ` Borislav Petkov
2016-09-12 15:14 ` Tom Lendacky
2016-09-12 16:35 ` Borislav Petkov
2016-09-12 16:55 ` Andy Lutomirski
2016-09-14 14:20 ` Tom Lendacky
2016-09-15 9:57 ` Matt Fleming
2016-09-15 16:52 ` Tom Lendacky
2016-08-22 22:37 ` [RFC PATCH v2 12/20] x86: Add support for changing memory encryption attribute Tom Lendacky
2016-09-09 17:23 ` Borislav Petkov
2016-09-12 15:41 ` Tom Lendacky
2016-09-12 16:41 ` Borislav Petkov
2016-08-22 22:37 ` [RFC PATCH v2 13/20] x86: Decrypt trampoline area if memory encryption is active Tom Lendacky
2016-09-09 17:34 ` Borislav Petkov
2016-09-12 15:43 ` Tom Lendacky
2016-08-22 22:38 ` [RFC PATCH v2 14/20] x86: DMA support for memory encryption Tom Lendacky
2016-09-12 10:58 ` Borislav Petkov
2016-09-14 13:36 ` Tom Lendacky
2016-08-22 22:38 ` [RFC PATCH v2 15/20] iommu/amd: AMD IOMMU " Tom Lendacky
2016-09-12 11:45 ` Borislav Petkov
2016-09-14 13:45 ` Tom Lendacky
2016-09-14 14:41 ` Borislav Petkov
2016-09-15 16:57 ` Tom Lendacky
2016-09-16 7:08 ` Borislav Petkov
2016-08-22 22:38 ` [RFC PATCH v2 16/20] x86: Check for memory encryption on the APs Tom Lendacky
2016-09-12 12:17 ` Borislav Petkov
2016-09-14 13:50 ` Tom Lendacky [this message]
2016-09-12 16:43 ` Borislav Petkov
2016-09-14 14:12 ` Tom Lendacky
2016-08-22 22:38 ` [RFC PATCH v2 17/20] x86: Do not specify encrypted memory for VGA mapping Tom Lendacky
2016-08-22 22:38 ` [RFC PATCH v2 18/20] x86/kvm: Enable Secure Memory Encryption of nested page tables Tom Lendacky
2016-09-12 14:35 ` Borislav Petkov
2016-09-14 14:02 ` Tom Lendacky
2016-08-22 22:38 ` [RFC PATCH v2 19/20] x86: Access the setup data through debugfs un-encrypted Tom Lendacky
2016-09-12 16:59 ` Borislav Petkov
2016-09-14 14:29 ` Tom Lendacky
2016-09-14 14:51 ` Borislav Petkov
2016-09-15 17:08 ` Tom Lendacky
2016-09-16 7:11 ` Borislav Petkov
2016-08-22 22:39 ` [RFC PATCH v2 20/20] x86: Add support to make use of Secure Memory Encryption Tom Lendacky
2016-09-12 17:08 ` Borislav Petkov
2016-09-14 14:31 ` Tom Lendacky
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