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

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Date:   Fri, 19 Jan 2018 16:35:24 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Tom Lendacky <thomas.lendacky@....com>
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 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.

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

thanks,

greg k-h