linux-kernel - Re: [tip: x86/urgent] x86/boot: Pull up cmdline preparation and early param parsing

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Message-ID: <50f25412-d616-1cc6-f07f-a29d80b4bd3b@suse.com>
Date:   Thu, 9 Dec 2021 16:26:55 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Borislav Petkov <bp@...en8.de>, John Dorminy <jdorminy@...hat.com>
Cc:     tip-bot2@...utronix.de, anjaneya.chagam@...el.com,
        dan.j.williams@...el.com, linux-kernel@...r.kernel.org,
        linux-tip-commits@...r.kernel.org, stable@...r.kernel.org,
        x86@...nel.org, Hugh Dickins <hughd@...gle.com>,
        "Patrick J. Volkerding" <volkerdi@...il.com>,
        Mike Rapoport <rppt@...nel.org>
Subject: Re: [tip: x86/urgent] x86/boot: Pull up cmdline preparation and early
 param parsing

On 09.12.21 16:19, Borislav Petkov wrote:
> + Hugh and Patrick.
> 
> On Thu, Dec 09, 2021 at 09:38:10AM -0500, John Dorminy wrote:
>> Greetings;
>>
>> It seems that this patch causes a mem= parameter to the kernel to have no effect, unfortunately...
>>
>> As far as I understand, the x86 mem parameter handler parse_memopt() (called by parse_early_param()) relies on being called after e820__memory_setup(): it simply removes any memory above the specified limit at that moment, allowing memory to later be hotplugged without regard for the initial limit. However, the initial non-hotplugged memory must already have been set up, in e820__memory_setup(), so that it can be removed in parse_memopt(); if parse_early_param() is called before e820__memory_setup(), as this change does, the parameter ends up having no effect.
>>
>> I apologize that I don't know how to fix this, but I'm happy to test patches.
> 
> Yeah, people have been reporting boot failures with mem= on the cmdline.
> 
> I think I see why, can you try this one:

Sigh. This will break Xen PV. Again. The comment above the call of
early_reserve_memory() tells you why.

Juergen

> 
> ---
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 6a190c7f4d71..6db971e61e4b 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -862,6 +862,8 @@ void __init setup_arch(char **cmdline_p)
>   	 */
>   	x86_configure_nx();
>   
> +	e820__memory_setup();
> +
>   	/*
>   	 * This parses early params and it needs to run before
>   	 * early_reserve_memory() because latter relies on such settings
> @@ -884,7 +886,6 @@ void __init setup_arch(char **cmdline_p)
>   	early_reserve_memory();
>   
>   	iomem_resource.end = (1ULL << boot_cpu_data.x86_phys_bits) - 1;
> -	e820__memory_setup();
>   	parse_setup_data();
>   
>   	copy_edd();
> ---
> 
> Leaving in the rest for the newly added folks.
> 
>> Typical dmesg output showing the lack of effect, built from the prior change and this change:
>>
>> With a git tree synced to 8d48bf8206f77aa8687f0e241e901e5197e52423^ (working):
>> [    0.000000] Command line: BOOT_IMAGE=(hd0,msdos1)/boot/vmlinuz-5.16.0-rc1 root=UUID=a4f7bd84-4f29-40bc-8c98-f4a72d0856c4 ro net.ifnames=0 crashkernel=128M mem=4G
>> ...
>> [    0.000000] BIOS-provided physical RAM map:
>> [    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009abff] usable
>> [    0.000000] BIOS-e820: [mem 0x000000000009ac00-0x000000000009ffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007dd3afff] usable
>> [    0.000000] BIOS-e820: [mem 0x000000007dd3b000-0x000000007deeffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x000000007def0000-0x000000007e0d3fff] ACPI NVS
>> [    0.000000] BIOS-e820: [mem 0x000000007e0d4000-0x000000007f367fff] reserved
>> [    0.000000] BIOS-e820: [mem 0x000000007f368000-0x000000007f7fffff] ACPI NVS
>> [    0.000000] BIOS-e820: [mem 0x0000000080000000-0x000000008fffffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed3ffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000207fffffff] usable
>> [    0.000000] e820: remove [mem 0x100000000-0xfffffffffffffffe] usable
>> [    0.000000] NX (Execute Disable) protection: active
>> [    0.000000] user-defined physical RAM map:
>> [    0.000000] user: [mem 0x0000000000000000-0x000000000009abff] usable
>> [    0.000000] user: [mem 0x000000000009ac00-0x000000000009ffff] reserved
>> [    0.000000] user: [mem 0x00000000000e0000-0x00000000000fffff] reserved
>> [    0.000000] user: [mem 0x0000000000100000-0x000000007dd3afff] usable
>> [    0.000000] user: [mem 0x000000007dd3b000-0x000000007deeffff] reserved
>> [    0.000000] user: [mem 0x000000007def0000-0x000000007e0d3fff] ACPI NVS
>> [    0.000000] user: [mem 0x000000007e0d4000-0x000000007f367fff] reserved
>> [    0.000000] user: [mem 0x000000007f368000-0x000000007f7fffff] ACPI NVS
>> [    0.000000] user: [mem 0x0000000080000000-0x000000008fffffff] reserved
>> [    0.000000] user: [mem 0x00000000fed1c000-0x00000000fed3ffff] reserved
>> [    0.000000] user: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
>> ...
>> [    0.025617] Memory: 1762876K/2061136K available (16394K kernel code, 3568K rwdata, 10324K rodata, 2676K init, 4924K bss, 298000K reserved, 0K cma-reserved)
>>
>> Synced 8d48bf8206f77aa8687f0e241e901e5197e52423 (not working):
>>
>> [    0.000000] Command line: BOOT_IMAGE=(hd0,msdos1)/boot/vmlinuz-5.16.0-rc4+ root=UUID=0e750e61-b92e-4708-a974-c50a3fb7e969 ro net.ifnames=0 crashkernel=128M mem=4G
>> [    0.000000] e820: remove [mem 0x100000000-0xfffffffffffffffe] usable
>> [    0.000000] BIOS-provided physical RAM map:
>> [    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009abff] usable
>> [    0.000000] BIOS-e820: [mem 0x000000000009ac00-0x000000000009ffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007dd3afff] usable
>> [    0.000000] BIOS-e820: [mem 0x000000007dd3b000-0x000000007deeffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x000000007def0000-0x000000007e0d3fff] ACPI NVS
>> [    0.000000] BIOS-e820: [mem 0x000000007e0d4000-0x000000007f367fff] reserved
>> [    0.000000] BIOS-e820: [mem 0x000000007f368000-0x000000007f7fffff] ACPI NVS
>> [    0.000000] BIOS-e820: [mem 0x0000000080000000-0x000000008fffffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed3ffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
>> [    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000207fffffff] usable
>> [    0.000000] NX (Execute Disable) protection: active
>> [    0.000000] user-defined physical RAM map:
>> [    0.000000] user: [mem 0x0000000000000000-0x000000000009abff] usable
>> [    0.000000] user: [mem 0x000000000009ac00-0x000000000009ffff] reserved
>> [    0.000000] user: [mem 0x00000000000e0000-0x00000000000fffff] reserved
>> [    0.000000] user: [mem 0x0000000000100000-0x000000007dd3afff] usable
>> [    0.000000] user: [mem 0x000000007dd3b000-0x000000007deeffff] reserved
>> [    0.000000] user: [mem 0x000000007def0000-0x000000007e0d3fff] ACPI NVS
>> [    0.000000] user: [mem 0x000000007e0d4000-0x000000007f367fff] reserved
>> [    0.000000] user: [mem 0x000000007f368000-0x000000007f7fffff] ACPI NVS
>> [    0.000000] user: [mem 0x0000000080000000-0x000000008fffffff] reserved
>> [    0.000000] user: [mem 0x00000000fed1c000-0x00000000fed3ffff] reserved
>> [    0.000000] user: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
>> [    0.000000] user: [mem 0x0000000100000000-0x000000207fffffff] usable
>> ...
>> [    0.695267] Memory: 131657608K/134181712K available (16394K kernel code, 3568K rwdata, 10328K rodata, 2676K init, 4924K bss, 2523844K reserved, 0K cma-reserved)
>>
> 


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