linux-kernel - Re: [PATCHv5 03/12] efi/x86: Get full memory map in allocate

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Date:   Wed, 27 Apr 2022 22:25:11 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joerg Roedel <jroedel@...e.de>,
        Ard Biesheuvel <ardb@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Varad Gautam <varad.gautam@...e.com>,
        Dario Faggioli <dfaggioli@...e.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Mike Rapoport <rppt@...nel.org>,
        David Hildenbrand <david@...hat.com>, x86@...nel.org,
        linux-mm@...ck.org, linux-coco@...ts.linux.dev,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv5 03/12] efi/x86: Get full memory map in allocate_e820()

On Mon, Apr 25, 2022 at 06:39:25AM +0300, Kirill A. Shutemov wrote:
>  static efi_status_t allocate_e820(struct boot_params *params,
> +				  struct efi_boot_memmap *map,
>  				  struct setup_data **e820ext,
>  				  u32 *e820ext_size)
>  {
> -	unsigned long map_size, desc_size, map_key;
>  	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;
> -
> -	nr_desc = map_size / desc_size + EFI_MMAP_NR_SLACK_SLOTS;
> +	status = efi_get_memory_map(map);
> +	if (status != EFI_SUCCESS)
> +		return status;
>  
> -	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;
> +			goto out;

Still silly, that label is useless then. Pasting the whole, simplified
function below.

It looks like it all boils down to propagating the retval up the chain...

static efi_status_t allocate_e820(struct boot_params *params,
                                  struct efi_boot_memmap *map,
                                  struct setup_data **e820ext,
                                  u32 *e820ext_size)
{
        efi_status_t status;
        __u32 nr_desc;

        status = efi_get_memory_map(map);
        if (status != EFI_SUCCESS)
                return status;

        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);
        }

        efi_bs_call(free_pool, *map->map);
        return status;
}

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette