Re: [PATCH v20 2/5] arm64: kdump: introduce some macros for crash kernel reservation

[Baoquan He <bhe@redhat.com>]

On 01/24/22 at 04:47pm, Zhen Lei wrote:
> From: Chen Zhou <chenzhou10@huawei.com>
> 
> Introduce macro CRASH_ALIGN for alignment, macro CRASH_ADDR_LOW_MAX
> for upper bound of low crash memory, macro CRASH_ADDR_HIGH_MAX for
> upper bound of high crash memory, use macros instead.
> 
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Dave Kleikamp <dave.kleikamp@oracle.com>
> ---
>  arch/arm64/mm/init.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 90f276d46b93bc6..6c653a2c7cff052 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -65,6 +65,12 @@ EXPORT_SYMBOL(memstart_addr);
>  phys_addr_t arm64_dma_phys_limit __ro_after_init;
>  
>  #ifdef CONFIG_KEXEC_CORE
> +/* Current arm64 boot protocol requires 2MB alignment */
> +#define CRASH_ALIGN		SZ_2M
> +
> +#define CRASH_ADDR_LOW_MAX	arm64_dma_phys_limit
> +#define CRASH_ADDR_HIGH_MAX	MEMBLOCK_ALLOC_ACCESSIBLE

MEMBLOCK_ALLOC_ACCESSIBLE is obvoiously a alloc flag for memblock
allocator, I don't think it's appropriate to make HIGH_MAX get its value.
You can make it as memblock.current_limit, or do not define it, but using
MEMBLOCK_ALLOC_ACCESSIBLE direclty in memblock_phys_alloc_range() with
a code comment. 


> +
>  /*
>   * reserve_crashkernel() - reserves memory for crash kernel
>   *
> @@ -75,7 +81,7 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init;
>  static void __init reserve_crashkernel(void)
>  {
>  	unsigned long long crash_base, crash_size;
> -	unsigned long long crash_max = arm64_dma_phys_limit;
> +	unsigned long long crash_max = CRASH_ADDR_LOW_MAX;
>  	int ret;
>  
>  	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> @@ -90,8 +96,7 @@ static void __init reserve_crashkernel(void)
>  	if (crash_base)
>  		crash_max = crash_base + crash_size;
>  
> -	/* Current arm64 boot protocol requires 2MB alignment */
> -	crash_base = memblock_phys_alloc_range(crash_size, SZ_2M,
> +	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
>  					       crash_base, crash_max);
>  	if (!crash_base) {
>  		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> -- 
> 2.25.1
>