linux-kernel - Re: [PATCH v2 2/2] x86, kexec_file_load: make it work with efi=noruntime or efi=old

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Message-ID: <20190121084352.GA15754@localhost.localdomain>
Date:   Mon, 21 Jan 2019 16:43:52 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     Kairui Song <kasong@...hat.com>, <linux-kernel@...r.kernel.org>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
        <x86@...nel.org>, Dave Young <dyoung@...hat.com>,
        Baoquan He <bhe@...hat.com>, <kexec@...ts.infradead.org>,
        <akpm@...ux-foundation.org>, <robert.moore@...el.com>,
        <erik.schmauss@...el.com>, <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v2 2/2] x86, kexec_file_load: make it work with
 efi=noruntime or efi=old_map

On Mon, Jan 21, 2019 at 09:29:32AM +0100, Borislav Petkov wrote:
>On Mon, Jan 21, 2019 at 09:18:30AM +0800, Chao Fan wrote:
>> So I have changed as this method and put in my mail thread, you may not
>> notice, so I put here for my function if I need to fill the
>> boot_parameters:
>> 
>> static inline acpi_physical_address get_boot_params_rsdp(void)
>> {
>>         return boot_params->acpi_rsdp_addr;
>> }
>
>Why do you need that silly wrapper?

Will drop it.

>
>> static acpi_physical_address get_rsdp_addr(void)
>> {
>>         bool boot_params_rsdp_exist;
>
>What's that bool supposed to do?

Since I didn't see where Xen to fill the value, if
boot_params->acpi_rsdp_addr is filled before my code, I just need to
read it. If when I try to read it but not found, then parse RSDP and
fill the RSDP address to boot_params->acpi_rsdp_addr.
>
>>         acpi_physical_address pa;
>> 
>>         pa = get_acpi_rsdp();
>> 
>>         if (!pa)
>>                 pa = get_boot_params_rsdp();
>> 
>>         if (!pa) {
>>                 pa = efi_get_rsdp_addr();
>>                 boot_params_rsdp_exist = false;
>>         }
>>         else
>>                 boot_params_rsdp_exist = true;
>> 
>>         if (!pa)
>>                 pa = bios_get_rsdp_addr();
>> 
>>         if (pa && !boot_params_rsdp_exist)
>>                 boot_params.acpi_rsdp_addr = pa;
>> 
>>         return pa;
>> }
>> 
>> At the same time, I notice kernel only parses it when
>> "#ifdef CONFIG_ACPI", we should keep sync with kernel, but I think
>> we are parsing SRAT, CONFIG_ACPI is needed sure, so I am going to
>> update the define of EARLY_SRAT_PARSE:
>> 
>> config EARLY_SRAT_PARSE
>>         bool "EARLY SRAT parsing"
>>         def_bool y
>>         depends on RANDOMIZE_BASE && MEMORY_HOTREMOVE && ACPI
>
>Actually, you don't need that anymore - make it unconditionally
>built-in. Because there are a bunch of users which need this and instead
>of complicating this config option with a bunch of dependencies, we can
>just as well have it always on.

If I need to fill boot_params->acpi_rsdp_addr, I think we can make it
unconditionally built-in.

Thanks,
Chao Fan

>
>Thx.
>
>-- 
>Regards/Gruss,
>    Boris.
>
>Good mailing practices for 400: avoid top-posting and trim the reply.
>
>