[PATCH] arm64: Use correct method to calculate nomap region boundaries

[Will Deacon]

On Fri, Oct 22, 2021 at 03:06:46PM +0800, Huacai Chen wrote:
> Nomap regions are treated as "reserved". When region boundaries are not
> page aligned, we usually increase the "reserved" regions rather than
> decrease them. So, we should use memblock_region_reserved_base_pfn()/
> memblock_region_reserved_end_pfn() instead of memblock_region_memory_
> base_pfn()/memblock_region_memory_base_pfn() to calculate boundaries.
> 
> Signed-off-by: Huacai Chen <chenhuacai at loongson.cn>
> ---
>  arch/arm64/kernel/setup.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index be5f85b0a24d..1e86d4c5ef8c 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -232,12 +232,14 @@ static void __init request_standard_resources(void)
>  		if (memblock_is_nomap(region)) {
>  			res->name  = "reserved";
>  			res->flags = IORESOURCE_MEM;
> +			res->start = __pfn_to_phys(memblock_region_reserved_base_pfn(region));
> +			res->end = __pfn_to_phys(memblock_region_reserved_end_pfn(region)) - 1;
>  		} else {
>  			res->name  = "System RAM";
>  			res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> +			res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
> +			res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
>  		}
> -		res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
> -		res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;

Under which circumstances would the nomap regions not be page-aligned? That
sounds like something we should prevent, rather than work around here.

Will