linux-kernel - Re: [PATCH v7 0/9] x86: Confine early 1:1 mapped startup code

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Date: Mon, 4 Mar 2024 11:07:21 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Ard Biesheuvel <ardb+git@...gle.com>, linux-kernel@...r.kernel.org
Cc: Ard Biesheuvel <ardb@...nel.org>,
 Kevin Loughlin <kevinloughlin@...gle.com>,
 Dionna Glaze <dionnaglaze@...gle.com>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, Andy Lutomirski
 <luto@...nel.org>, Brian Gerst <brgerst@...il.com>
Subject: Re: [PATCH v7 0/9] x86: Confine early 1:1 mapped startup code

On 2/27/24 09:19, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@...nel.org>
> 
> This is resend #2 of v5 [0] with some touchups applied.
> 
> Changes since v6:
> - Drop flawed patch to move some SME/SEV related calls out of the early
>    boot path to avoid the potential need for backporting patches #6/#7
>    to kernels where SEV support may not be crucial. This problem will be
>    dealt with if/when it arises while doing those backports.
> 
> Changes since v5:
> - drop patches that have been merged
> - rebase onto latest tip/x86/boot
> - fix comment regarding CR4.PGE wrt flushing of global TLB entries
> - avoid adding startup code to .noinstr.text as it triggers objtool
>    warnings
> 
> [0] https://lore.kernel.org/all/20240221113506.2565718-18-ardb+git@google.com/
> 
> Cc: Kevin Loughlin <kevinloughlin@...gle.com>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: Dionna Glaze <dionnaglaze@...gle.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Andy Lutomirski <luto@...nel.org>
> Cc: Brian Gerst <brgerst@...il.com>

For the series, tested bare metal boots with mem_encrypt=on / 
mem_encrypt=off and boots of SVM, SEV, SEV-ES and SEV-SNP guests.

Tested-by: Tom Lendacky <thomas.lendacky@....com>

> 
> Ard Biesheuvel (9):
>    x86/startup_64: Simplify CR4 handling in startup code
>    x86/startup_64: Defer assignment of 5-level paging global variables
>    x86/startup_64: Simplify calculation of initial page table address
>    x86/startup_64: Simplify virtual switch on primary boot
>    efi/libstub: Add generic support for parsing mem_encrypt=
>    x86/boot: Move mem_encrypt= parsing to the decompressor
>    x86/sme: Move early SME kernel encryption handling into .head.text
>    x86/sev: Move early startup code into .head.text section
>    x86/startup_64: Drop global variables keeping track of LA57 state
> 
>   arch/x86/boot/compressed/misc.c                | 15 ++++
>   arch/x86/boot/compressed/misc.h                |  4 -
>   arch/x86/boot/compressed/pgtable_64.c          | 12 ---
>   arch/x86/boot/compressed/sev.c                 |  3 +
>   arch/x86/boot/compressed/vmlinux.lds.S         |  1 +
>   arch/x86/include/asm/mem_encrypt.h             |  8 +-
>   arch/x86/include/asm/pgtable_64_types.h        | 43 ++++-----
>   arch/x86/include/asm/sev.h                     | 10 +--
>   arch/x86/include/uapi/asm/bootparam.h          |  1 +
>   arch/x86/kernel/cpu/common.c                   |  2 -
>   arch/x86/kernel/head64.c                       | 61 ++-----------
>   arch/x86/kernel/head_64.S                      | 93 ++++++++------------
>   arch/x86/kernel/sev-shared.c                   | 23 +++--
>   arch/x86/kernel/sev.c                          | 14 +--
>   arch/x86/lib/Makefile                          | 13 ---
>   arch/x86/mm/kasan_init_64.c                    |  3 -
>   arch/x86/mm/mem_encrypt_identity.c             | 83 +++++------------
>   drivers/firmware/efi/libstub/efi-stub-helper.c |  8 ++
>   drivers/firmware/efi/libstub/efistub.h         |  2 +-
>   drivers/firmware/efi/libstub/x86-stub.c        |  3 +
>   20 files changed, 147 insertions(+), 255 deletions(-)
>