linux-kernel - Re: [PATCH 2/2] x86/xen/efi: Init only efi struct members used by Xen

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Date:   Wed, 21 Jun 2017 09:53:57 +0200
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Daniel Kiper <daniel.kiper@...cle.com>
Cc:     "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        xen-devel@...ts.xenproject.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>,
        Matt Fleming <matt@...eblueprint.co.uk>
Subject: Re: [PATCH 2/2] x86/xen/efi: Init only efi struct members used by Xen

On 20 June 2017 at 22:14, Daniel Kiper <daniel.kiper@...cle.com> wrote:
> Current approach, wholesale efi struct initialization from efi_xen, is not
> good. Usually if new member is defined then it is properly initialized in
> drivers/firmware/efi/efi.c but not in arch/x86/xen/efi.c. As I saw it happened
> a few times until now. So, let's initialize only efi struct members used by
> Xen to avoid such issues in the future.
>
> Signed-off-by: Daniel Kiper <daniel.kiper@...cle.com>

Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>

> ---
>  arch/x86/xen/efi.c |   45 ++++++++++++---------------------------------
>  1 file changed, 12 insertions(+), 33 deletions(-)
>
> diff --git a/arch/x86/xen/efi.c b/arch/x86/xen/efi.c
> index 30bb2e8..01b9faf 100644
> --- a/arch/x86/xen/efi.c
> +++ b/arch/x86/xen/efi.c
> @@ -54,38 +54,6 @@
>         .tables         = EFI_INVALID_TABLE_ADDR  /* Initialized later. */
>  };
>
> -static const struct efi efi_xen __initconst = {
> -       .systab                   = NULL, /* Initialized later. */
> -       .runtime_version          = 0,    /* Initialized later. */
> -       .mps                      = EFI_INVALID_TABLE_ADDR,
> -       .acpi                     = EFI_INVALID_TABLE_ADDR,
> -       .acpi20                   = EFI_INVALID_TABLE_ADDR,
> -       .smbios                   = EFI_INVALID_TABLE_ADDR,
> -       .smbios3                  = EFI_INVALID_TABLE_ADDR,
> -       .sal_systab               = EFI_INVALID_TABLE_ADDR,
> -       .boot_info                = EFI_INVALID_TABLE_ADDR,
> -       .hcdp                     = EFI_INVALID_TABLE_ADDR,
> -       .uga                      = EFI_INVALID_TABLE_ADDR,
> -       .uv_systab                = EFI_INVALID_TABLE_ADDR,
> -       .fw_vendor                = EFI_INVALID_TABLE_ADDR,
> -       .runtime                  = EFI_INVALID_TABLE_ADDR,
> -       .config_table             = EFI_INVALID_TABLE_ADDR,
> -       .get_time                 = xen_efi_get_time,
> -       .set_time                 = xen_efi_set_time,
> -       .get_wakeup_time          = xen_efi_get_wakeup_time,
> -       .set_wakeup_time          = xen_efi_set_wakeup_time,
> -       .get_variable             = xen_efi_get_variable,
> -       .get_next_variable        = xen_efi_get_next_variable,
> -       .set_variable             = xen_efi_set_variable,
> -       .query_variable_info      = xen_efi_query_variable_info,
> -       .update_capsule           = xen_efi_update_capsule,
> -       .query_capsule_caps       = xen_efi_query_capsule_caps,
> -       .get_next_high_mono_count = xen_efi_get_next_high_mono_count,
> -       .reset_system             = xen_efi_reset_system,
> -       .set_virtual_address_map  = NULL, /* Not used under Xen. */
> -       .flags                    = 0     /* Initialized later. */
> -};
> -
>  static efi_system_table_t __init *xen_efi_probe(void)
>  {
>         struct xen_platform_op op = {
> @@ -102,7 +70,18 @@ static efi_system_table_t __init *xen_efi_probe(void)
>
>         /* Here we know that Xen runs on EFI platform. */
>
> -       efi = efi_xen;
> +       efi.get_time = xen_efi_get_time;
> +       efi.set_time = xen_efi_set_time;
> +       efi.get_wakeup_time = xen_efi_get_wakeup_time;
> +       efi.set_wakeup_time = xen_efi_set_wakeup_time;
> +       efi.get_variable = xen_efi_get_variable;
> +       efi.get_next_variable = xen_efi_get_next_variable;
> +       efi.set_variable = xen_efi_set_variable;
> +       efi.query_variable_info = xen_efi_query_variable_info;
> +       efi.update_capsule = xen_efi_update_capsule;
> +       efi.query_capsule_caps = xen_efi_query_capsule_caps;
> +       efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
> +       efi.reset_system = xen_efi_reset_system;
>
>         efi_systab_xen.tables = info->cfg.addr;
>         efi_systab_xen.nr_tables = info->cfg.nent;
> --
> 1.7.10.4
>