linux-kernel - Re: [PATCH v2] x86/efi: Add additional efi tables for unencrypted mapping checks

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Date:   Tue, 25 Feb 2020 13:35:59 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2] x86/efi: Add additional efi tables for unencrypted
 mapping checks

On 2/25/20 1:28 PM, Ard Biesheuvel wrote:
> On Tue, 25 Feb 2020 at 20:21, Tom Lendacky <thomas.lendacky@....com> wrote:
>>
>> On 2/25/20 12:12 PM, Ard Biesheuvel wrote:
>>> On Tue, 25 Feb 2020 at 19:10, Tom Lendacky <thomas.lendacky@....com> wrote:
>>>>
>>>> On 2/25/20 11:58 AM, Ard Biesheuvel wrote:
>>>>> On Tue, 25 Feb 2020 at 18:54, Tom Lendacky <thomas.lendacky@....com> wrote:
>>>>>>
>>>>>> On 2/25/20 11:45 AM, Ard Biesheuvel wrote:
>>>>>>> On Tue, 25 Feb 2020 at 18:41, Tom Lendacky <thomas.lendacky@....com> wrote:
>>>>>>>>
>>>>>>>> When booting with SME active, EFI tables must be mapped unencrypted since
>>>>>>>> they were built by UEFI in unencrypted memory. Update the list of tables
>>>>>>>> to be checked during early_memremap() processing to account for new EFI
>>>>>>>> tables.
>>>>>>>>
>>>>>>>> This fixes a bug where an EFI TPM log table has been created by UEFI, but
>>>>>>>> it lives in memory that has been marked as usable rather than reserved.
>>>>>>>>
>>>>>>>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>>>>>>>>
>>>>>>>> ---
>>>>>>>> Changes since v1:
>>>>>>>> - Re-spun against EFI tree
>>>>>>>
>>>>>>> Which one? Surely not the one in the link I included?
>>>>>>
>>>>>> I did a git clone of
>>>>>>
>>>>>>   git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi.git
>>>>>>
>>>>>> and checked out branch next. Not sure what I missed...
>>>>>>
>>>>>
>>>>> Weird. Do you see commit 5d288dbd88606d8f215c7138b10649115d79cadd on
>>>>> that branch? It removes rng_seed from struct efi, hence my request to
>>>>> rebase your patch.
>>>>
>>>> I had just assumed you wanted a cleaner version and didn't realize that
>>>> rng_seed was removed from struct efi. My bad for not building.
>>>>
>>>>>
>>>>> IMO, best is to simply drop the 'static' from rng_seed, rename it to
>>>>> efi_rng_seed, and drop an extern declaration in linux/efi.h so it is
>>>>> accessible from your code. I'm reluctant to put it back in struct efi.
>>>>
>>>> Ok, I'll re-work the patch.
>>>>
>>>
>>> OK
>>>
>>> Btw if you want the TPM part of the fix to go to -stable, better to
>>> split them in two (and I'll put a cc:stable on the tpm one)
>>
>> I had thought about stable, but the fix gets tricky since the two tables
>> were added at different times (4.16 and 5.3) and the efi_tables array was
>> moved from drivers/firmware/efi/efi.c to arch/x86/platform/efi/efi.c in 5.4.
>>
>> I could do the two TPM tables each as their own patch and add an
>> appropriate Cc: stable # v4.16.x-, etc., if you don't think that's
>> overkill. The array move shouldn't be too hard to adjust for in stable.
>> Thoughts?
>>
> 
> So v5.4/v5.5 seems straight-forward then, no? Once that one is in, we
> can do one specially for v4.19

Works for me.

Thanks,
Tom

>