efi: Prevent GICv3 WARN() by mapping the memreserve table before first use

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. This results in a
WARN() splat because the LPI tables cannot be reserved persistently,
which will result in silent memory corruption after a kexec reboot.

So instead, invoke the initialization performed by the initcall from
efi_mem_reserve_persistent() itself as well, but keep the initcall so
that the init is guaranteed to have been called before SMP boot.

Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Tested-by: Jan Glauber <jglauber@cavium.com>
Tested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 63eb322d89c8 ("efi: Permit calling efi_mem_reserve_persistent() ...")
Link: http://lkml.kernel.org/r/20181123215132.7951-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index fad7c62cfc0e422f3b8459653a561f4dee770a6e..415849bab2339a4168d9fff236b8302a02adc284 100644 (file)
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -969,13 +969,33 @@ 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;
 
-int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
+static int __init efi_memreserve_map_root(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 (WARN_ON_ONCE(!efi_memreserve_root))
+               return -ENOMEM;
+       return 0;
+}
+
+int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 {
        struct linux_efi_memreserve *rsv;
+       int rc;
 
-       if (!efi_memreserve_root)
+       if (efi_memreserve_root == (void *)ULONG_MAX)
                return -ENODEV;
 
+       if (!efi_memreserve_root) {
+               rc = efi_memreserve_map_root();
+               if (rc)
+                       return rc;
+       }
+
        rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
        if (!rsv)
                return -ENOMEM;
@@ -993,14 +1013,10 @@ int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 
 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;
+       if (efi_memreserve_root)
+               return 0;
+       if (efi_memreserve_map_root())
+               efi_memreserve_root = (void *)ULONG_MAX;
        return 0;
 }
 early_initcall(efi_memreserve_root_init);