arm64: mm: ignore memory above supported physical address size

When booting a kernel without 52-bit PA support (e.g. a kernel with 4k
pages) on a system with 52-bit memory, the kernel will currently try to
use the 52-bit memory and crash. Fix this by ignoring any memory higher
than what the kernel supports.

Fixes: f77d281 ("arm64: enable 52-bit physical address support")
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/mm/init.c

@@ -366,6 +366,9 @@ void __init arm64_memblock_init(void)
 	/* Handle linux,usable-memory-range property */
 	fdt_enforce_memory_region();
 
+	/* Remove memory above our supported physical address size */
+	memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX);
+
 	/*
 	 * Ensure that the linear region takes up exactly half of the kernel
 	 * virtual address space. This way, we can distinguish a linear address