Add kernel plumbing to reserve memory regions persistently on a EFI system by adding entries to the MEMRESERVE linked list.
Signed-off-by: Ard Biesheuvel <[email protected]> --- drivers/firmware/efi/efi.c | 32 ++++++++++++++++++++ include/linux/efi.h | 1 + 2 files changed, 33 insertions(+) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 688132ac8a0a..249eb70691b0 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -962,6 +962,38 @@ bool efi_is_table_address(unsigned long phys_addr) return false; } +static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock); + +int efi_mem_reserve_persistent(phys_addr_t addr, u64 size) +{ + struct linux_efi_memreserve *rsv, *parent; + + if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR) + return -ENODEV; + + rsv = kmalloc(sizeof(*rsv), GFP_KERNEL); + if (!rsv) + return -ENOMEM; + + parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB); + if (!parent) { + kfree(rsv); + return -ENOMEM; + } + + rsv->base = addr; + rsv->size = size; + + spin_lock(&efi_mem_reserve_persistent_lock); + rsv->next = parent->next; + parent->next = __pa(rsv); + spin_unlock(&efi_mem_reserve_persistent_lock); + + memunmap(parent); + + return 0; +} + #ifdef CONFIG_KEXEC static int update_efi_random_seed(struct notifier_block *nb, unsigned long code, void *unused) diff --git a/include/linux/efi.h b/include/linux/efi.h index c72599b8b344..c753d8530da6 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1043,6 +1043,7 @@ extern int __init efi_uart_console_only (void); extern u64 efi_mem_desc_end(efi_memory_desc_t *md); extern int efi_mem_desc_lookup(u64 phys_addr, efi_memory_desc_t *out_md); extern void efi_mem_reserve(phys_addr_t addr, u64 size); +extern int efi_mem_reserve_persistent(phys_addr_t addr, u64 size); extern void efi_initialize_iomem_resources(struct resource *code_resource, struct resource *data_resource, struct resource *bss_resource); extern void efi_reserve_boot_services(void); -- 2.17.1
