From 16993c0f0a43213e23666ea40e9163887f593ac7 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 6 Nov 2019 17:43:21 -0800 Subject: 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 Signed-off-by: Dan Williams Acked-by: Thomas Gleixner Signed-off-by: Rafael J. Wysocki --- arch/arm64/mm/mmu.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/arm64') diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 60c929f3683b..2c385fe05fde 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -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); } -- cgit v1.2.3