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

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Date:   Fri, 19 Jan 2018 09:27:47 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Gabriel C <nix.or.die@...il.com>, Borislav Petkov <bp@...en8.de>,
        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 1/19/2018 9:11 AM, Greg Kroah-Hartman wrote:
> On Fri, Jan 19, 2018 at 09:03:52AM -0600, Tom Lendacky wrote:
>> 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.
> 
> What are the git commit ids?   That's all I need :)

Hi Greg,

Here are the commit ids:
  1303880179e6 (“x86/mm: Clean up register saving in the __enc_copy() assembly code”)
  bacf6b499e11 (“x86/mm: Use a struct to reduce parameters for SME PGD mapping”)
  2b5d00b6c2cd (“x86/mm: Centralize PMD flags in sme_encrypt_kernel()”)
  cc5f01e28d6c (“x86/mm: Prepare sme_encrypt_kernel() for PAGE aligned encryption”)
  107cd2532181 (“x86/mm: Encrypt the initrd earlier for BSP microcode update”)

The last commit won't apply cleanly on 4.14.  There was a change in
arch/x86/kernel/setup.c for SEV support.  The actual patch to that file
is very small it just removes the call to sme_early_encrypt() and the
associated comment.  I can submit a new version of that patch if you
want, just let me know.

Thanks Greg!

Tom

> 
> thanks,
> 
> greg k-h
>