[RFT PATCH] efi: map memreserve table before first use

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Mapping the MEMRESERVE EFI configuration table from an early initcall
is too late: the GICv3 ITS code that creates persistent reservations
for the boot CPU's LPI tables is invoked from init_IRQ(), which runs
much earlier than the handling of the initcalls.

So instead, move the initialization performed by the initcall into
efi_mem_reserve_persistent() itself.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 drivers/firmware/efi/efi.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index fad7c62cfc0e..40de2f6734cc 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -967,15 +967,23 @@ bool efi_is_table_address(unsigned long phys_addr)
 }
 
 static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
-static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
+static struct linux_efi_memreserve *efi_memreserve_root;
 
 int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 {
 	struct linux_efi_memreserve *rsv;
 
-	if (!efi_memreserve_root)
+	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
 		return -ENODEV;
 
+	if (!efi_memreserve_root) {
+		efi_memreserve_root = memremap(efi.mem_reserve,
+					       sizeof(*efi_memreserve_root),
+					       MEMREMAP_WB);
+		if (WARN_ON_ONCE(!efi_memreserve_root))
+			return -ENOMEM;
+	}
+
 	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
 	if (!rsv)
 		return -ENOMEM;
@@ -991,20 +999,6 @@ int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 	return 0;
 }
 
-static int __init efi_memreserve_root_init(void)
-{
-	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
-		return -ENODEV;
-
-	efi_memreserve_root = memremap(efi.mem_reserve,
-				       sizeof(*efi_memreserve_root),
-				       MEMREMAP_WB);
-	if (!efi_memreserve_root)
-		return -ENOMEM;
-	return 0;
-}
-early_initcall(efi_memreserve_root_init);
-
 #ifdef CONFIG_KEXEC
 static int update_efi_random_seed(struct notifier_block *nb,
 				  unsigned long code, void *unused)
-- 
2.17.1