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References: <20230507234618.18067-1-kirill.shutemov@linux.intel.com> <20230507234618.18067-3-kirill.shutemov@linux.intel.com>
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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Mon, 8 May 2023 09:19:37 +0200
Message-ID: <CAMj1kXFNXMmAsnQovWq18LrOnNL4=3Puamvz7p1ufynJfVEOug@mail.gmail.com>
Subject: Re: [PATCHv10 02/11] efi/x86: Get full memory map in allocate_e820()
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joerg Roedel <jroedel@suse.de>,
        Andi Kleen <ak@linux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Dario Faggioli <dfaggioli@suse.com>,
        Mike Rapoport <rppt@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        aarcange@redhat.com, peterx@redhat.com, x86@kernel.org,
        linux-mm@kvack.org, linux-coco@lists.linux.dev,
        linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Borislav Petkov <bp@suse.de>
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On Mon, 8 May 2023 at 01:46, Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
>
> Currently allocate_e820() is only interested in the size of map and size
> of memory descriptor to determine how many e820 entries the kernel
> needs.
>
> UEFI Specification version 2.9 introduces a new memory type --
> unaccepted memory. To track unaccepted memory kernel needs to allocate
> a bitmap. The size of the bitmap is dependent on the maximum physical
> address present in the system. A full memory map is required to find
> the maximum address.
>
> Modify allocate_e820() to get a full memory map.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Borislav Petkov <bp@suse.de>

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>  drivers/firmware/efi/libstub/x86-stub.c | 26 +++++++++++--------------
>  1 file changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
> index a0bfd31358ba..fff81843169c 100644
> --- a/drivers/firmware/efi/libstub/x86-stub.c
> +++ b/drivers/firmware/efi/libstub/x86-stub.c
> @@ -681,28 +681,24 @@ static efi_status_t allocate_e820(struct boot_params *params,
>                                   struct setup_data **e820ext,
>                                   u32 *e820ext_size)
>  {
> -       unsigned long map_size, desc_size, map_key;
> +       struct efi_boot_memmap *map;
>         efi_status_t status;
> -       __u32 nr_desc, desc_version;
> +       __u32 nr_desc;
>
> -       /* Only need the size of the mem map and size of each mem descriptor */
> -       map_size = 0;
> -       status = efi_bs_call(get_memory_map, &map_size, NULL, &map_key,
> -                            &desc_size, &desc_version);
> -       if (status != EFI_BUFFER_TOO_SMALL)
> -               return (status != EFI_SUCCESS) ? status : EFI_UNSUPPORTED;
> +       status = efi_get_memory_map(&map, false);
> +       if (status != EFI_SUCCESS)
> +               return status;
>
> -       nr_desc = map_size / desc_size + EFI_MMAP_NR_SLACK_SLOTS;
> -
> -       if (nr_desc > ARRAY_SIZE(params->e820_table)) {
> -               u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table);
> +       nr_desc = map->map_size / map->desc_size;
> +       if (nr_desc > ARRAY_SIZE(params->e820_table) - EFI_MMAP_NR_SLACK_SLOTS) {
> +               u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table) +
> +                       EFI_MMAP_NR_SLACK_SLOTS;
>
>                 status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size);
> -               if (status != EFI_SUCCESS)
> -                       return status;
>         }
>
> -       return EFI_SUCCESS;
> +       efi_bs_call(free_pool, map);
> +       return status;
>  }
>
>  struct exit_boot_struct {
> --
> 2.39.3
>