linux-kernel - Re: [PATCH v3 3/5] x86/boot: Get the max address from SRAT

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Message-ID: <20190905135134.GC20805@MiWiFi-R3L-srv>
Date:   Thu, 5 Sep 2019 21:51:34 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Masayoshi Mizuma <msys.mizuma@...il.com>
Cc:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Masayoshi Mizuma <m.mizuma@...fujitsu.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/5] x86/boot: Get the max address from SRAT

On 08/30/19 at 05:47pm, Masayoshi Mizuma wrote:
> From: Masayoshi Mizuma <m.mizuma@...fujitsu.com>
> 
> Get the max address from SRAT and write it into boot_params->max_addr.
> 
> Signed-off-by: Masayoshi Mizuma <m.mizuma@...fujitsu.com>
> ---
>  arch/x86/boot/compressed/acpi.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> index 908a1bfab..ba2bc5ab9 100644
> --- a/arch/x86/boot/compressed/acpi.c
> +++ b/arch/x86/boot/compressed/acpi.c
> @@ -362,16 +362,24 @@ static unsigned long get_acpi_srat_table(void)
>  	return 0;
>  }
>  
> -static void subtable_parse(struct acpi_subtable_header *sub_table, int *num)
> +static void subtable_parse(struct acpi_subtable_header *sub_table, int *num,
> +		unsigned long *max_addr)
>  {
>  	struct acpi_srat_mem_affinity *ma;
> +	unsigned long addr;
>  
>  	ma = (struct acpi_srat_mem_affinity *)sub_table;
>  
> -	if (!(ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && ma->length) {
> -		immovable_mem[*num].start = ma->base_address;
> -		immovable_mem[*num].size = ma->length;
> -		(*num)++;
> +	if (ma->length) {
> +		if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) {
> +			addr = ma->base_address + ma->length;
> +			if (addr > *max_addr)
> +				*max_addr = addr;

Can we return max_addr or only pass out the max_addr, then let the
max_addr compared and got outside of subtable_parse()? This can keep
subtable_parse() really only doing parsing work.

Personal opinion, see what maintainers and other reviewers will say.

Thanks
Baoquan

> +		} else {
> +			immovable_mem[*num].start = ma->base_address;
> +			immovable_mem[*num].size = ma->length;
> +			(*num)++;
> +		}
>  	}
>  }
>  
> @@ -391,6 +399,7 @@ int count_immovable_mem_regions(void)
>  	struct acpi_subtable_header *sub_table;
>  	struct acpi_table_header *table_header;
>  	char arg[MAX_ACPI_ARG_LENGTH];
> +	unsigned long max_addr = 0;
>  	int num = 0;
>  
>  	if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
> @@ -409,7 +418,7 @@ int count_immovable_mem_regions(void)
>  		sub_table = (struct acpi_subtable_header *)table;
>  		if (sub_table->type == ACPI_SRAT_TYPE_MEMORY_AFFINITY) {
>  
> -			subtable_parse(sub_table, &num);
> +			subtable_parse(sub_table, &num, &max_addr);
>  
>  			if (num >= MAX_NUMNODES*2) {
>  				debug_putstr("Too many immovable memory regions, aborting.\n");
> @@ -418,6 +427,9 @@ int count_immovable_mem_regions(void)
>  		}
>  		table += sub_table->length;
>  	}
> +
> +	boot_params->max_addr = max_addr;
> +
>  	return num;
>  }
>  #endif /* CONFIG_RANDOMIZE_BASE && CONFIG_MEMORY_HOTREMOVE */
> -- 
> 2.18.1
>