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

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Date:   Fri, 19 Jan 2018 09:56:37 -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 9:35 AM, Greg Kroah-Hartman wrote:
> On Fri, Jan 19, 2018 at 09:27:47AM -0600, Tom Lendacky wrote:
>> 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.
> 
> A backported version of that would be great, thanks.

Ok, I'll send that out as soon as possible.  Since it is a changed patch
I was planning to remove the Tested-by, Signed-off-by (except for my sign
off), etc. or would you prefer I leave them in this case?

> 
> And are any of these needed in older kernels like 4.4 and 4.9?

Nope, SME was new in 4.14.

Thanks,
Tom

> 
> thanks,
> 
> greg k-h
>