linux-kernel - Re: [patch 13/13] Remove (now unused) EFI_UV1

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Date:   Wed, 1 Jul 2020 17:28:52 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Steve Wahl <steve.wahl@....com>
Cc:     Jonathan Corbet <corbet@....net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Juergen Gross <jgross@...e.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Oliver Neukum <oneukum@...e.com>,
        Mike Travis <mike.travis@....com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Benjamin Thiel <b.thiel@...teo.de>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        James Morris <jmorris@...ei.org>,
        David Howells <dhowells@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Dave Young <dyoung@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Austin Kim <austindh.kim@...il.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        Russ Anderson <rja@....com>
Subject: Re: [patch 13/13] Remove (now unused) EFI_UV1_MEMMAP from efi.h

On Wed, 1 Jul 2020 at 16:18, <steve.wahl@....com> wrote:
>
> With UV1 support removed, EFI_UV1_MEMMAP is no longer used.
>
> Signed-off-by: Steve Wahl <steve.wahl@....com>

Reviewed-by: Ard Biesheuvel <ardb@...nel.org>

> ---
>  arch/x86/include/asm/efi.h |   20 ++------------------
>  1 file changed, 2 insertions(+), 18 deletions(-)
>
> --- linux.orig/arch/x86/include/asm/efi.h       2020-06-17 14:21:49.798542440 -0500
> +++ linux/arch/x86/include/asm/efi.h    2020-06-17 14:28:55.830071857 -0500
> @@ -22,17 +22,7 @@ extern unsigned long efi_fw_vendor, efi_
>   *
>   * This is the main reason why we're doing stable VA mappings for RT
>   * services.
> - *
> - * SGI UV1 machines are known to be incompatible with this scheme, so we
> - * provide an opt-out for these machines via a DMI quirk that sets the
> - * attribute below.
>   */
> -#define EFI_UV1_MEMMAP         EFI_ARCH_1
> -
> -static inline bool efi_have_uv1_memmap(void)
> -{
> -       return IS_ENABLED(CONFIG_X86_UV) && efi_enabled(EFI_UV1_MEMMAP);
> -}
>
>  #define EFI32_LOADER_SIGNATURE "EL32"
>  #define EFI64_LOADER_SIGNATURE "EL64"
> @@ -122,9 +112,7 @@ struct efi_scratch {
>         efi_sync_low_kernel_mappings();                                 \
>         kernel_fpu_begin();                                             \
>         firmware_restrict_branch_speculation_start();                   \
> -                                                                       \
> -       if (!efi_have_uv1_memmap())                                     \
> -               efi_switch_mm(&efi_mm);                                 \
> +       efi_switch_mm(&efi_mm);                                         \
>  })
>
>  #define arch_efi_call_virt(p, f, args...)                              \
> @@ -132,9 +120,7 @@ struct efi_scratch {
>
>  #define arch_efi_call_virt_teardown()                                  \
>  ({                                                                     \
> -       if (!efi_have_uv1_memmap())                                     \
> -               efi_switch_mm(efi_scratch.prev_mm);                     \
> -                                                                       \
> +       efi_switch_mm(efi_scratch.prev_mm);                             \
>         firmware_restrict_branch_speculation_end();                     \
>         kernel_fpu_end();                                               \
>  })
> @@ -176,8 +162,6 @@ extern void efi_delete_dummy_variable(vo
>  extern void efi_switch_mm(struct mm_struct *mm);
>  extern void efi_recover_from_page_fault(unsigned long phys_addr);
>  extern void efi_free_boot_services(void);
> -extern pgd_t * __init efi_uv1_memmap_phys_prolog(void);
> -extern void __init efi_uv1_memmap_phys_epilog(pgd_t *save_pgd);
>
>  /* kexec external ABI */
>  struct efi_setup_data {
>