linux-kernel - Re: [PATCH v3 0/5] x86: SME: BSP/SME microcode update fix

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Message-ID: <b541ff4d-8131-ac09-1dbe-f549ceb47c6f@amd.com>
Date:   Fri, 19 Jan 2018 09:03:52 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Gabriel C <nix.or.die@...il.com>, Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, Brijesh Singh <brijesh.singh@....com>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v3 0/5] x86: SME: BSP/SME microcode update fix

On 1/15/2018 4:47 PM, Gabriel C wrote:
> On 11.01.2018 19:33, Borislav Petkov wrote:
>> On Wed, Jan 10, 2018 at 01:25:45PM -0600, Tom Lendacky wrote:
>>> This patch series addresses an issue when SME is active and the BSP
>>> is attempting to check for and load microcode during load_ucode_bsp().
>>> Since the initrd has not been decrypted (yet) and the virtual address
>>> of the initrd treats the memory as encrypted, the CPIO archive parsing
>>> fails to locate the microcode.
>>>
>>> This series moves the encryption of the initrd into the early boot code
>>> and encrypts it at the same time that the kernel is encrypted.  Since
>>> the initrd is now encrypted, the CPIO archive parsing succeeds in
>>> properly locating the microcode.
>>>
>>> The following patches are included in this fix:
>>> - Cleanup register saving in arch/x86/mm/mem_encrypt_boot.S
>>> - Reduce parameters and complexity for creating the SME PGD mappings
>>> - Centralize the use of the PMD flags used in sme_encrypt_kernel() in
>>>    preparation for using PTE flags also.
>>> - Prepare sme_encrypt_kernel() to handle PAGE aligned encryption, not
>>>    just 2MB large page aligned encryption.
>>> - Encrypt the initrd in sme_encrypt_kernel() when the kernel is being
>>>    encrypted.
>>>
>>> This patch series is based on tip/master.
>>>
>>> ---
>>>
>>> Changes from v2:
>>> - General code cleanup based on feedback.
>>>
>>> Changes from v1:
>>> - Additional patch to cleanup the register saving performed in
>>>    arch/x86/mm/mem_encrypt_boot.S in prep for changes made in the
>>>    remainder of the patchset.
>>> - Additional patch to reduce parameters and complexity for creating the
>>>    SME PGD mappings by introducing and using a structure for referencing
>>>    the PGD to populate, the pagetable allocation area, the
>>> virtual/physical
>>>    addresses being mapped and the pagetable flags to be used.
>>> - Consolidate PMD/PTE mapping code to reduce duplication.
>>>
>>> Tom Lendacky (5):
>>>        x86/mm: Cleanup register saving in mem_encrypt_boot.S
>>>        x86/mm: Use a struct to reduce parameters for SME PGD mapping
>>>        x86/mm: Centralize PMD flags in sme_encrypt_kernel()
>>>        x86/mm: Prepare sme_encrypt_kernel() for PAGE aligned encryption
>>>        x86/mm: Encrypt the initrd earlier for BSP microcode update
>>>
>>>
>>>   arch/x86/include/asm/mem_encrypt.h |    4
>>>   arch/x86/kernel/head64.c           |    4
>>>   arch/x86/kernel/setup.c            |   10 -
>>>   arch/x86/mm/mem_encrypt.c          |  356
>>> ++++++++++++++++++++++++++----------
>>>   arch/x86/mm/mem_encrypt_boot.S     |   80 ++++----
>>>   5 files changed, 308 insertions(+), 146 deletions(-)
>>
>> All 5:
>>
>> Reviewed-by: Borislav Petkov <bp@...e.de>
>>
> 
> Guys , are these patches going to be part of 4.15 ?
> 
> With mem_encrypt=on without these patches microcode loading doesn't
> work right. Also @stable 4.14 would need the fixes too.

It looks like these patches have been pulled into 4.15.  I did forget
to cc stable, so I'll follow-up with a separate email to have these
back-ported to the 4.14 stable tree.

Thanks,
Tom

> 
> 
> Regards,
> 
> Gabriel C