Re: [PATCH v7 1/8] mm/memblock: Tag memblocks with crypto capabilities

[Mike Rapoport <rppt@kernel.org>]

On Mon, Apr 25, 2022 at 02:15:19PM -0300, Martin Fernandez wrote:
> Add the capability to mark regions of the memory memory_type able of
> hardware memory encryption.
> 
> Also add the capability to query if all regions of a memory node are
> able to do hardware memory encryption to call it when initializing the
> nodes. Warn the user if a node has both encryptable and
> non-encryptable regions.
> 
> Signed-off-by: Martin Fernandez <martin.fernandez@eclypsium.com>
> ---
>  include/linux/memblock.h |  5 ++++
>  mm/memblock.c            | 62 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 67 insertions(+)
> 
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 50ad19662a32..00c4f1a20335 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -40,6 +40,7 @@ extern unsigned long long max_possible_pfn;
>   * via a driver, and never indicated in the firmware-provided memory map as
>   * system RAM. This corresponds to IORESOURCE_SYSRAM_DRIVER_MANAGED in the
>   * kernel resource tree.
> + * @MEMBLOCK_CRYPTO_CAPABLE: capable of hardware encryption
>   */
>  enum memblock_flags {
>  	MEMBLOCK_NONE		= 0x0,	/* No special request */
> @@ -47,6 +48,7 @@ enum memblock_flags {
>  	MEMBLOCK_MIRROR		= 0x2,	/* mirrored region */
>  	MEMBLOCK_NOMAP		= 0x4,	/* don't add to kernel direct mapping */
>  	MEMBLOCK_DRIVER_MANAGED = 0x8,	/* always detected via a driver */
> +	MEMBLOCK_CRYPTO_CAPABLE = 0x10,	/* capable of hardware encryption */
>  };
>  
>  /**
> @@ -120,6 +122,9 @@ int memblock_physmem_add(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);
> +bool memblock_node_is_crypto_capable(int nid);
> +int memblock_mark_crypto_capable(phys_addr_t base, phys_addr_t size);
> +int memblock_clear_crypto_capable(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);
> diff --git a/mm/memblock.c b/mm/memblock.c
> index e4f03a6e8e56..fe62f81572e6 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -191,6 +191,40 @@ bool __init_memblock memblock_overlaps_region(struct memblock_type *type,
>  	return i < type->cnt;
>  }
>  
> +/**
> + * memblock_node_is_crypto_capable - get if whole node is capable
> + * of encryption
> + * @nid: number of node
> + *
> + * Iterate over all memory memblock_type and find if all regions under
> + * node @nid are capable of hardware encryption.
> + *
> + * Return:
> + * true if every region in memory memblock_type is capable of

I'd s/in memory memblock_type/in @nid

> + * encryption, false otherwise.
> + */
> +bool __init_memblock memblock_node_is_crypto_capable(int nid)
> +{
> +	struct memblock_region *region;
> +	int crypto_capables = 0;
> +	int not_crypto_capables = 0;
> +
> +	for_each_mem_region(region) {
> +		if (memblock_get_region_node(region) == nid) {
> +			if (region->flags & MEMBLOCK_CRYPTO_CAPABLE)
> +				crypto_capables++;
> +			else
> +				not_crypto_capables++;
> +		}
> +	}
> +
> +	if (crypto_capables > 0 && not_crypto_capables > 0)
> +		pr_warn("Node %d has %d regions that are encryptable and %d regions that aren't",
> +			nid, not_crypto_capables, crypto_capables);
> +
> +	return not_crypto_capables == 0;

This will return true for memoryless nodes as well. Do you mean to consider
them as capable of encryption?

> +}
> +
>  /**
>   * __memblock_find_range_bottom_up - find free area utility in bottom-up
>   * @start: start of candidate range
> @@ -891,6 +925,34 @@ static int __init_memblock memblock_setclr_flag(phys_addr_t base,
>  	return 0;
>  }
>  
> +/**
> + * memblock_mark_crypto_capable - Mark memory regions capable of hardware
> + * encryption with flag MEMBLOCK_CRYPTO_CAPABLE.
> + * @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_crypto_capable(phys_addr_t base,
> +						 phys_addr_t size)
> +{
> +	return memblock_setclr_flag(base, size, 1, MEMBLOCK_CRYPTO_CAPABLE);
> +}
> +
> +/**
> + * memblock_clear_crypto_capable - Clear flag MEMBLOCK_CRYPTO 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_crypto_capable(phys_addr_t base,
> +						  phys_addr_t size)
> +{
> +	return memblock_setclr_flag(base, size, 0, MEMBLOCK_CRYPTO_CAPABLE);
> +}
> +
>  /**
>   * memblock_mark_hotplug - Mark hotpluggable memory with flag MEMBLOCK_HOTPLUG.
>   * @base: the base phys addr of the region
> -- 
> 2.30.2
> 

-- 
Sincerely yours,
Mike.