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Date: Fri, 1 Apr 2022 08:59:24 -0700
From: Vijay Balakrishna <vijayb@...ux.microsoft.com>
To: Kefeng Wang <wangkefeng.wang@...wei.com>, catalin.marinas@....com,
will@...nel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: f.fainelli@...il.com, Pasha Tatashin <pasha.tatashin@...een.com>
Subject: Re: [PATCH v2 resend 1/3] arm64: mm: Do not defer
reserve_crashkernel() if only ZONE_DMA32
On 3/31/2022 12:40 AM, Kefeng Wang wrote:
> The kernel could be benefit due to BLOCK_MAPPINGS, see commit
> 031495635b46 ("arm64: Do not defer reserve_crashkernel() for
> platforms with no DMA memory zones"), if only with ZONE_DMA32,
> set arm64_dma_phys_limit to max_zone_phys(32) earlier in
> arm64_memblock_init(), so platforms with just ZONE_DMA32 config
> enabled will be benefit.
nit --
- "will be benefit" => will benefit
On further look I feel we can getaway without dma32_phys_limit static
global and replace with two separate calls to max_zone_phys(32)? Just a
thought. If you decide to keep it then a better location would be
immediately above arm64_memblock_init() definition where it is
initialized can improve code readability.
Thanks,
Vijay
>
> Cc: Vijay Balakrishna <vijayb@...ux.microsoft.com>
> Cc: Pasha Tatashin <pasha.tatashin@...een.com>
> Cc: Will Deacon <will@...nel.org>
> Reviewed-by: Vijay Balakrishna <vijayb@...ux.microsoft.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> ---
> arch/arm64/mm/init.c | 23 +++++++++++++----------
> arch/arm64/mm/mmu.c | 6 ++----
> 2 files changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 8ac25f19084e..fb01eb489fa9 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -65,8 +65,9 @@ EXPORT_SYMBOL(memstart_addr);
> * Memory reservation for crash kernel either done early or deferred
> * depending on DMA memory zones configs (ZONE_DMA) --
> *
> - * In absence of ZONE_DMA configs arm64_dma_phys_limit initialized
> - * here instead of max_zone_phys(). This lets early reservation of
> + * In absence of ZONE_DMA and ZONE_DMA32 configs arm64_dma_phys_limit
> + * initialized here and if only with ZONE_DMA32 arm64_dma_phys_limit
> + * initialised to dma32_phys_limit. This lets early reservation of
> * crash kernel memory which has a dependency on arm64_dma_phys_limit.
> * Reserving memory early for crash kernel allows linear creation of block
> * mappings (greater than page-granularity) for all the memory bank rangs.
> @@ -84,6 +85,7 @@ EXPORT_SYMBOL(memstart_addr);
> * Note: Page-granularity mapppings are necessary for crash kernel memory
> * range for shrinking its size via /sys/kernel/kexec_crash_size interface.
> */
> +static phys_addr_t __ro_after_init dma32_phys_limit;
> #if IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32)
> phys_addr_t __ro_after_init arm64_dma_phys_limit;
> #else
> @@ -160,11 +162,10 @@ static phys_addr_t __init max_zone_phys(unsigned int zone_bits)
> static void __init zone_sizes_init(unsigned long min, unsigned long max)
> {
> unsigned long max_zone_pfns[MAX_NR_ZONES] = {0};
> - unsigned int __maybe_unused acpi_zone_dma_bits;
> - unsigned int __maybe_unused dt_zone_dma_bits;
> - phys_addr_t __maybe_unused dma32_phys_limit = max_zone_phys(32);
> -
> #ifdef CONFIG_ZONE_DMA
> + unsigned int acpi_zone_dma_bits;
> + unsigned int dt_zone_dma_bits;
> +
> acpi_zone_dma_bits = fls64(acpi_iort_dma_get_max_cpu_address());
> dt_zone_dma_bits = fls64(of_dma_get_max_cpu_address(NULL));
> zone_dma_bits = min3(32U, dt_zone_dma_bits, acpi_zone_dma_bits);
> @@ -173,8 +174,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
> #endif
> #ifdef CONFIG_ZONE_DMA32
> max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit);
> - if (!arm64_dma_phys_limit)
> - arm64_dma_phys_limit = dma32_phys_limit;
> #endif
> max_zone_pfns[ZONE_NORMAL] = max;
>
> @@ -336,8 +335,12 @@ void __init arm64_memblock_init(void)
>
> early_init_fdt_scan_reserved_mem();
>
> - if (!IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32))
> + dma32_phys_limit = max_zone_phys(32);
> + if (!IS_ENABLED(CONFIG_ZONE_DMA)) {
> + if (IS_ENABLED(CONFIG_ZONE_DMA32))
> + arm64_dma_phys_limit = dma32_phys_limit;
> reserve_crashkernel();
> + }
>
> high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
> }
> @@ -385,7 +388,7 @@ void __init bootmem_init(void)
> * request_standard_resources() depends on crashkernel's memory being
> * reserved, so do it here.
> */
> - if (IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32))
> + if (IS_ENABLED(CONFIG_ZONE_DMA))
> reserve_crashkernel();
>
> memblock_dump_all();
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 626ec32873c6..23734481318a 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -529,8 +529,7 @@ static void __init map_mem(pgd_t *pgdp)
>
> #ifdef CONFIG_KEXEC_CORE
> if (crash_mem_map) {
> - if (IS_ENABLED(CONFIG_ZONE_DMA) ||
> - IS_ENABLED(CONFIG_ZONE_DMA32))
> + if (IS_ENABLED(CONFIG_ZONE_DMA))
> flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
> else if (crashk_res.end)
> memblock_mark_nomap(crashk_res.start,
> @@ -571,8 +570,7 @@ static void __init map_mem(pgd_t *pgdp)
> * through /sys/kernel/kexec_crash_size interface.
> */
> #ifdef CONFIG_KEXEC_CORE
> - if (crash_mem_map &&
> - !IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) {
> + if (crash_mem_map && !IS_ENABLED(CONFIG_ZONE_DMA)) {
> if (crashk_res.end) {
> __map_memblock(pgdp, crashk_res.start,
> crashk_res.end + 1,
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