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: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@ -1061,6 +1061,8 @@ int arch_add_memory(int nid, u64 start, u64 size,
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__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
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size, PAGE_KERNEL, __pgd_pgtable_alloc, flags);
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memblock_clear_nomap(start, size);
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return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
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restrictions);
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}
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@ -163,6 +163,15 @@ static __init int is_usable_memory(efi_memory_desc_t *md)
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case EFI_BOOT_SERVICES_DATA:
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case EFI_CONVENTIONAL_MEMORY:
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case EFI_PERSISTENT_MEMORY:
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/*
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* Special purpose memory is 'soft reserved', which means it
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* is set aside initially, but can be hotplugged back in or
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* be assigned to the dax driver after boot.
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*/
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if (efi_soft_reserve_enabled() &&
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(md->attribute & EFI_MEMORY_SP))
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return false;
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/*
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* According to the spec, these regions are no longer reserved
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* after calling ExitBootServices(). However, we can only use
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@ -121,6 +121,30 @@ static int __init arm_enable_runtime_services(void)
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return 0;
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}
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if (efi_soft_reserve_enabled()) {
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efi_memory_desc_t *md;
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for_each_efi_memory_desc(md) {
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int md_size = md->num_pages << EFI_PAGE_SHIFT;
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struct resource *res;
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if (!(md->attribute & EFI_MEMORY_SP))
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continue;
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res = kzalloc(sizeof(*res), GFP_KERNEL);
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if (WARN_ON(!res))
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break;
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res->start = md->phys_addr;
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res->end = md->phys_addr + md_size - 1;
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res->name = "Soft Reserved";
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res->flags = IORESOURCE_MEM;
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res->desc = IORES_DESC_SOFT_RESERVED;
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insert_resource(&iomem_resource, res);
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}
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}
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if (efi_runtime_disabled()) {
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pr_info("EFI runtime services will be disabled.\n");
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return 0;
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@ -146,6 +146,11 @@ static efi_status_t reserve_kernel_base(efi_system_table_t *sys_table_arg,
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continue;
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case EFI_CONVENTIONAL_MEMORY:
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/* Skip soft reserved conventional memory */
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if (efi_soft_reserve_enabled() &&
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(desc->attribute & EFI_MEMORY_SP))
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continue;
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/*
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* Reserve the intersection between this entry and the
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* region.
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@ -46,6 +46,10 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
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if (md->type != EFI_CONVENTIONAL_MEMORY)
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return 0;
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if (efi_soft_reserve_enabled() &&
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(md->attribute & EFI_MEMORY_SP))
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return 0;
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region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1);
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first_slot = round_up(md->phys_addr, align);
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