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From: Ard Biesheuvel <ardb@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Ard Biesheuvel <ardb+git@google.com>,
	linux-kernel@vger.kernel.org,
	 Kevin Loughlin <kevinloughlin@google.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	 Dionna Glaze <dionnaglaze@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	 Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	 Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	Justin Stitt <justinstitt@google.com>,
	 Kees Cook <keescook@chromium.org>,
	Brian Gerst <brgerst@gmail.com>,
	linux-arch@vger.kernel.org,  llvm@lists.linux.dev
Subject: Re: [PATCH v3 06/19] x86/startup_64: Drop global variables keeping track of LA57 state
Date: Sun, 11 Feb 2024 23:36:51 +0100	[thread overview]
Message-ID: <CAMj1kXG5+KEAE5F0EFkZCkt1244M3UBJXH_O3ULg0oRHV2YnmQ@mail.gmail.com> (raw)
In-Reply-To: <20240210104039.GAZcdSp7dRbgqBy3fg@fat_crate.local>

On Sat, 10 Feb 2024 at 11:41, Borislav Petkov <bp@alien8.de> wrote:
>
> On Fri, Feb 09, 2024 at 01:55:02PM +0000, Ard Biesheuvel wrote:
> > I was trying to get rid of global variable assignments and accesses
> > from the 1:1 mapping, but since we cannot get rid of those entirely,
> > we might just keep __pgtable_l5_enabled but use RIP_REL_REF() in the
> > accessors, and move the assignment to the asm startup code.
>
> Yeah.
>
> >    asm(ALTERNATIVE_TERNARY(
> >        "movq %%cr4, %[reg] \n\t btl %[la57], %k[reg]" CC_SET(c),
> >        %P[feat], "stc", "clc")
> >        : [reg] "=r" (r), CC_OUT(c) (ret)
> >        : [feat] "i" (X86_FEATURE_LA57),
> >          [la57] "i" (X86_CR4_LA57_BIT)
> >        : "cc");
>
> Creative :)
>
> > but we'd still have two versions in that case.
>
> Yap. RIP_REL_REF() ain't too bad ...
>

We can actually rip all of that stuff out, and have only a single
implementation of pgtable_l5_enabled() that is not based on a variable
at all. It results in a nice cleanup, but I'll keep it as a separate
patch in the next revision so we can easily drop it if preferred.

  reply	other threads:[~2024-02-11 22:37 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-29 18:05 [PATCH v3 00/19] x86: Confine early 1:1 mapped startup code Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 01/19] efi/libstub: Add generic support for parsing mem_encrypt= Ard Biesheuvel
2024-01-31  7:31   ` Borislav Petkov
2024-02-01 16:23     ` Kevin Loughlin
2024-02-01 16:28       ` Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 02/19] x86/boot: Move mem_encrypt= parsing to the decompressor Ard Biesheuvel
2024-01-31  8:35   ` Borislav Petkov
2024-01-31  9:12     ` Ard Biesheuvel
2024-01-31  9:29       ` Borislav Petkov
2024-01-31  9:59         ` Ard Biesheuvel
2024-02-01 14:17         ` Tom Lendacky
2024-02-01 16:15           ` Ard Biesheuvel
2024-02-02 16:35             ` [PATCH] x86/Kconfig: Remove CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT Borislav Petkov
2024-02-02 16:47               ` Ard Biesheuvel
2024-02-03 10:50               ` [tip: x86/sev] " tip-bot2 for Borislav Petkov (AMD)
2024-01-29 18:05 ` [PATCH v3 03/19] x86/startup_64: Drop long return to initial_code pointer Ard Biesheuvel
2024-01-31 13:44   ` Borislav Petkov
2024-01-31 13:57     ` Ard Biesheuvel
2024-01-31 14:07       ` Ard Biesheuvel
2024-01-31 16:29         ` Borislav Petkov
2024-01-31 18:14   ` [tip: x86/boot] " tip-bot2 for Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 04/19] x86/startup_64: Simplify calculation of initial page table address Ard Biesheuvel
2024-02-05 10:40   ` Borislav Petkov
2024-01-29 18:05 ` [PATCH v3 05/19] x86/startup_64: Simplify CR4 handling in startup code Ard Biesheuvel
2024-02-06 18:21   ` Borislav Petkov
2024-02-07 10:38     ` Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 06/19] x86/startup_64: Drop global variables keeping track of LA57 state Ard Biesheuvel
2024-02-07 13:29   ` Borislav Petkov
2024-02-09 13:55     ` Ard Biesheuvel
2024-02-10 10:40       ` Borislav Petkov
2024-02-11 22:36         ` Ard Biesheuvel [this message]
2024-01-29 18:05 ` [PATCH v3 07/19] x86/startup_64: Simplify virtual switch on primary boot Ard Biesheuvel
2024-02-07 14:50   ` Borislav Petkov
2024-01-29 18:05 ` [PATCH v3 08/19] x86/head64: Replace pointer fixups with PIE codegen Ard Biesheuvel
2024-02-12 10:29   ` Borislav Petkov
2024-02-12 11:52     ` Ard Biesheuvel
2024-02-12 14:18       ` Borislav Petkov
2024-01-29 18:05 ` [PATCH v3 09/19] x86/head64: Simplify GDT/IDT initialization code Ard Biesheuvel
2024-02-12 14:37   ` Borislav Petkov
2024-02-12 15:23     ` Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 10/19] asm-generic: Add special .pi.text section for position independent code Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 11/19] x86: Move return_thunk to __pitext section Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 12/19] x86/head64: Move early startup code into __pitext Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 13/19] modpost: Warn about calls from __pitext into other text sections Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 14/19] x86/coco: Make cc_set_mask() static inline Ard Biesheuvel
2024-01-30 23:16   ` Kevin Loughlin
2024-01-30 23:36     ` Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 15/19] x86/sev: Make all code reachable from 1:1 mapping __pitext Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 16/19] x86/sev: Avoid WARN() in early code Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 17/19] x86/sev: Use PIC codegen for early SEV startup code Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 18/19] x86/sev: Drop inline asm LEA instructions for RIP-relative references Ard Biesheuvel
2024-01-29 18:05 ` [PATCH v3 19/19] x86/startup_64: Don't bother setting up GS before the kernel is mapped Ard Biesheuvel

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