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SubjectRe: [PATCH V11 2/5] mm/memblock: Introduce MEMBLOCK_BOOT flag
On Fri, Jan 10, 2020 at 08:39:12AM +0530, Anshuman Khandual wrote:
> On arm64 platform boot memory should never be hot removed due to certain
> platform specific constraints. Hence the platform would like to override
> earlier added arch call back arch_memory_removable() for this purpose. In
> order to reject boot memory hot removal request, it needs to first track
> them at runtime. In the future, there might be other platforms requiring
> runtime boot memory enumeration. Hence lets expand the existing generic
> memblock framework for this purpose rather then creating one just for
> arm64 platforms.
>
> This introduces a new memblock flag MEMBLOCK_BOOT along with helpers which
> can be marked by given platform on all memory regions discovered during
> boot.

We already have MEMBLOCK_HOTPLUG to mark hotpluggable region. Can't we use
it for your use-case?

> Cc: Mike Rapoport <rppt@linux.ibm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> include/linux/memblock.h | 10 ++++++++++
> mm/memblock.c | 37 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 47 insertions(+)
>
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index b38bbef..fb04c87 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -31,12 +31,14 @@ extern unsigned long long max_possible_pfn;
> * @MEMBLOCK_HOTPLUG: hotpluggable region
> * @MEMBLOCK_MIRROR: mirrored region
> * @MEMBLOCK_NOMAP: don't add to kernel direct mapping
> + * @MEMBLOCK_BOOT: memory received from firmware during boot
> */
> enum memblock_flags {
> MEMBLOCK_NONE = 0x0, /* No special request */
> MEMBLOCK_HOTPLUG = 0x1, /* hotpluggable region */
> MEMBLOCK_MIRROR = 0x2, /* mirrored region */
> MEMBLOCK_NOMAP = 0x4, /* don't add to kernel direct mapping */
> + MEMBLOCK_BOOT = 0x8, /* memory received from firmware during boot */
> };
>
> /**
> @@ -116,6 +118,8 @@ int memblock_reserve(phys_addr_t base, phys_addr_t size);
> void memblock_trim_memory(phys_addr_t align);
> bool memblock_overlaps_region(struct memblock_type *type,
> phys_addr_t base, phys_addr_t size);
> +int memblock_mark_boot(phys_addr_t base, phys_addr_t size);
> +int memblock_clear_boot(phys_addr_t base, phys_addr_t size);
> int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size);
> int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
> int memblock_mark_mirror(phys_addr_t base, phys_addr_t size);
> @@ -216,6 +220,11 @@ static inline bool memblock_is_nomap(struct memblock_region *m)
> return m->flags & MEMBLOCK_NOMAP;
> }
>
> +static inline bool memblock_is_boot(struct memblock_region *m)
> +{
> + return m->flags & MEMBLOCK_BOOT;
> +}
> +
> #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
> int memblock_search_pfn_nid(unsigned long pfn, unsigned long *start_pfn,
> unsigned long *end_pfn);
> @@ -449,6 +458,7 @@ void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size);
> void memblock_mem_limit_remove_map(phys_addr_t limit);
> bool memblock_is_memory(phys_addr_t addr);
> bool memblock_is_map_memory(phys_addr_t addr);
> +bool memblock_is_boot_memory(phys_addr_t addr);
> bool memblock_is_region_memory(phys_addr_t base, phys_addr_t size);
> bool memblock_is_reserved(phys_addr_t addr);
> bool memblock_is_region_reserved(phys_addr_t base, phys_addr_t size);
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 4bc2c7d..e10207f 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -865,6 +865,30 @@ static int __init_memblock memblock_setclr_flag(phys_addr_t base,
> }
>
> /**
> + * memblock_mark_bootmem - Mark boot memory with flag MEMBLOCK_BOOT.
> + * @base: the base phys addr of the region
> + * @size: the size of the region
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +int __init_memblock memblock_mark_boot(phys_addr_t base, phys_addr_t size)
> +{
> + return memblock_setclr_flag(base, size, 1, MEMBLOCK_BOOT);
> +}
> +
> +/**
> + * memblock_clear_bootmem - Clear flag MEMBLOCK_BOOT for a specified region.
> + * @base: the base phys addr of the region
> + * @size: the size of the region
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +int __init_memblock memblock_clear_boot(phys_addr_t base, phys_addr_t size)
> +{
> + return memblock_setclr_flag(base, size, 0, MEMBLOCK_BOOT);
> +}
> +
> +/**
> * memblock_mark_hotplug - Mark hotpluggable memory with flag MEMBLOCK_HOTPLUG.
> * @base: the base phys addr of the region
> * @size: the size of the region
> @@ -974,6 +998,10 @@ static bool should_skip_region(struct memblock_region *m, int nid, int flags)
> if ((flags & MEMBLOCK_MIRROR) && !memblock_is_mirror(m))
> return true;
>
> + /* if we want boot memory skip non-boot memory regions */
> + if ((flags & MEMBLOCK_BOOT) && !memblock_is_boot(m))
> + return true;
> +
> /* skip nomap memory unless we were asked for it explicitly */
> if (!(flags & MEMBLOCK_NOMAP) && memblock_is_nomap(m))
> return true;
> @@ -1785,6 +1813,15 @@ bool __init_memblock memblock_is_map_memory(phys_addr_t addr)
> return !memblock_is_nomap(&memblock.memory.regions[i]);
> }
>
> +bool __init_memblock memblock_is_boot_memory(phys_addr_t addr)
> +{
> + int i = memblock_search(&memblock.memory, addr);
> +
> + if (i == -1)
> + return false;
> + return memblock_is_boot(&memblock.memory.regions[i]);
> +}
> +
> #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
> int __init_memblock memblock_search_pfn_nid(unsigned long pfn,
> unsigned long *start_pfn, unsigned long *end_pfn)
> --
> 2.7.4
>

--
Sincerely yours,
Mike.

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