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

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Date:   Mon, 15 Jan 2018 23:47:24 +0100
From:   Gabriel C <nix.or.die@...il.com>
To:     Borislav Petkov <bp@...en8.de>,
        Tom Lendacky <thomas.lendacky@....com>
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>
Subject: Re: [PATCH v3 0/5] x86: SME: BSP/SME microcode update fix

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.


Regards,

Gabriel C