Commit 16993c0f authored by Dan Williams's avatar Dan Williams Committed by Rafael J. Wysocki
Browse files

arm/efi: EFI soft reservation to memblock 



UEFI 2.8 defines an EFI_MEMORY_SP attribute bit to augment the
interpretation of the EFI Memory Types as "reserved for a specific
purpose".

The proposed Linux behavior for specific purpose memory is that it is
reserved for direct-access (device-dax) by default and not available for
any kernel usage, not even as an OOM fallback.  Later, through udev
scripts or another init mechanism, these device-dax claimed ranges can
be reconfigured and hot-added to the available System-RAM with a unique
node identifier. This device-dax management scheme implements "soft" in
the "soft reserved" designation by allowing some or all of the
reservation to be recovered as typical memory. This policy can be
disabled at compile-time with CONFIG_EFI_SOFT_RESERVE=n, or runtime with
efi=nosoftreserve.

For this patch, update the ARM paths that consider
EFI_CONVENTIONAL_MEMORY to optionally take the EFI_MEMORY_SP attribute
into account as a reservation indicator. Publish the soft reservation as
IORES_DESC_SOFT_RESERVED memory, similar to x86.

(Based on an original patch by Ard)

Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 262b45ae

arch/arm64/mm/mmu.c

+2 −0
Original line number Diff line number Diff line
@@ -1061,6 +1061,8 @@ int arch_add_memory(int nid, u64 start, u64 size, 
	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),

			     size, PAGE_KERNEL, __pgd_pgtable_alloc, flags);



	memblock_clear_nomap(start, size);



	return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,

			   restrictions);

}

drivers/firmware/efi/arm-init.c

+9 −0
Original line number Diff line number Diff line
@@ -163,6 +163,15 @@ static __init int is_usable_memory(efi_memory_desc_t *md) 
	case EFI_BOOT_SERVICES_DATA:

	case EFI_CONVENTIONAL_MEMORY:

	case EFI_PERSISTENT_MEMORY:

		/*

		 * Special purpose memory is 'soft reserved', which means it

		 * is set aside initially, but can be hotplugged back in or

		 * be assigned to the dax driver after boot.

		 */

		if (efi_soft_reserve_enabled() &&

		    (md->attribute & EFI_MEMORY_SP))

			return false;



		/*

		 * According to the spec, these regions are no longer reserved

		 * after calling ExitBootServices(). However, we can only use

drivers/firmware/efi/arm-runtime.c

+24 −0
Original line number Diff line number Diff line
@@ -121,6 +121,30 @@ static int __init arm_enable_runtime_services(void) 
		return 0;

	}



	if (efi_soft_reserve_enabled()) {

		efi_memory_desc_t *md;



		for_each_efi_memory_desc(md) {

			int md_size = md->num_pages << EFI_PAGE_SHIFT;

			struct resource *res;



			if (!(md->attribute & EFI_MEMORY_SP))

				continue;



			res = kzalloc(sizeof(*res), GFP_KERNEL);

			if (WARN_ON(!res))

				break;



			res->start	= md->phys_addr;

			res->end	= md->phys_addr + md_size - 1;

			res->name	= "Soft Reserved";

			res->flags	= IORESOURCE_MEM;

			res->desc	= IORES_DESC_SOFT_RESERVED;



			insert_resource(&iomem_resource, res);

		}

	}



	if (efi_runtime_disabled()) {

		pr_info("EFI runtime services will be disabled.\n");

		return 0;

drivers/firmware/efi/libstub/arm32-stub.c

+5 −0
Original line number Diff line number Diff line
@@ -146,6 +146,11 @@ static efi_status_t reserve_kernel_base(efi_system_table_t *sys_table_arg, 
			continue;



		case EFI_CONVENTIONAL_MEMORY:

			/* Skip soft reserved conventional memory */

			if (efi_soft_reserve_enabled() &&

			    (desc->attribute & EFI_MEMORY_SP))

				continue;



			/*

			 * Reserve the intersection between this entry and the

			 * region.

drivers/firmware/efi/libstub/random.c

+4 −0
Original line number Diff line number Diff line
@@ -46,6 +46,10 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md, 
	if (md->type != EFI_CONVENTIONAL_MEMORY)

		return 0;



	if (efi_soft_reserve_enabled() &&

	    (md->attribute & EFI_MEMORY_SP))

		return 0;



	region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1);



	first_slot = round_up(md->phys_addr, align);

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