linux-kernel - Re: [RFC] efi/tpm: add efi.tpm_log as a reserved region in 820_table

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Message-ID: <6b2cc4c4-4354-4b29-bc73-c1384b90dfc6@gmail.com>
Date: Thu, 12 Sep 2024 14:54:56 +0100
From: Usama Arif <usamaarif642@...il.com>
To: Ard Biesheuvel <ardb@...nel.org>, Breno Leitao <leitao@...ian.org>
Cc: linux-efi@...r.kernel.org, kexec@...ts.infradead.org,
 ebiederm@...ssion.com, bhe@...hat.com, vgoyal@...hat.com,
 tglx@...utronix.de, dave.hansen@...ux.intel.com, x86@...nel.org,
 linux-kernel@...r.kernel.org, rmikey@...a.com, gourry@...rry.net
Subject: Re: [RFC] efi/tpm: add efi.tpm_log as a reserved region in
 820_table_firmware



On 12/09/2024 14:10, Ard Biesheuvel wrote:
> Does the below help at all?
> 
> --- a/drivers/firmware/efi/tpm.c
> +++ b/drivers/firmware/efi/tpm.c
> @@ -60,7 +60,7 @@ int __init efi_tpm_eventlog_init(void)
>         }
> 
>         tbl_size = sizeof(*log_tbl) + log_tbl->size;
> -       memblock_reserve(efi.tpm_log, tbl_size);
> +       efi_mem_reserve(efi.tpm_log, tbl_size);
> 
>         if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
>                 pr_info("TPM Final Events table not present\n");

Unfortunately not. efi_mem_reserve updates e820_table, while kexec looks at /sys/firmware/memmap
which is e820_table_firmware.

arch_update_firmware_area introduced in the RFC patch does the same thing as efi_mem_reserve does at
its end, just with e820_table_firmware instead of e820_table.
i.e. efi_mem_reserve does:
	e820__range_update(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED);
	e820__update_table(e820_table);

while arch_update_firmware_area does:
	e820__range_update_firmware(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED);
	e820__update_table(e820_table_firmware);

Thanks,
Usama