From 379d8da3353e18da7cb077e4ae7b52432decffcd Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 13 Jul 2021 19:43:26 +0100 Subject: [PATCH] firmware/efi: Tell memblock about EFI iomem reservations commit 2bab693a608bdf614b9fcd44083c5100f34b9f77 upstream. kexec_load_file() relies on the memblock infrastructure to avoid stamping over regions of memory that are essential to the survival of the system. However, nobody seems to agree how to flag these regions as reserved, and (for example) EFI only publishes its reservations in /proc/iomem for the benefit of the traditional, userspace based kexec tool. On arm64 platforms with GICv3, this can result in the payload being placed at the location of the LPI tables. Shock, horror! Let's augment the EFI reservation code with a memblock_reserve() call, protecting our dear tables from the secondary kernel invasion. Reported-by: Moritz Fischer Tested-by: Moritz Fischer Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Cc: Ard Biesheuvel Cc: James Morse Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman --- drivers/firmware/efi/efi.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 3a2b60736915..415d7b3a59f8 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -975,6 +975,7 @@ static int __init efi_memreserve_map_root(void) static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size) { struct resource *res, *parent; + int ret; res = kzalloc(sizeof(struct resource), GFP_ATOMIC); if (!res) @@ -987,7 +988,17 @@ static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size) /* we expect a conflict with a 'System RAM' region */ parent = request_resource_conflict(&iomem_resource, res); - return parent ? request_resource(parent, res) : 0; + ret = parent ? request_resource(parent, res) : 0; + + /* + * Given that efi_mem_reserve_iomem() can be called at any + * time, only call memblock_reserve() if the architecture + * keeps the infrastructure around. + */ + if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK) && !ret) + memblock_reserve(addr, size); + + return ret; } int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)