KVM: arm64: Make __io_map_base static

The __io_map_base variable is used at EL2 to track the end of the
hypervisor's "private" VA range in nVHE protected mode. However it
doesn't need to be used outside of mm.c, so let's make it static to keep
all the hyp VA allocation logic in one place.
Signed-off-by: Quentin Perret <qperret@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211208152300.2478542-5-qperret@google.com

arch/arm64/kvm/hyp/include/nvhe/mm.h

@@ -15,7 +15,6 @@ extern struct memblock_region kvm_nvhe_sym(hyp_memory)[];
 extern unsigned int kvm_nvhe_sym(hyp_memblock_nr);
 extern struct kvm_pgtable pkvm_pgtable;
 extern hyp_spinlock_t pkvm_pgd_lock;
-extern u64 __io_map_base;
 
 int hyp_create_idmap(u32 hyp_va_bits);
 int hyp_map_vectors(void);

arch/arm64/kvm/hyp/nvhe/mm.c

@@ -18,11 +18,12 @@
 
 struct kvm_pgtable pkvm_pgtable;
 hyp_spinlock_t pkvm_pgd_lock;
-u64 __io_map_base;
 
 struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
 unsigned int hyp_memblock_nr;
 
+static u64 __io_map_base;
+
 static int __pkvm_create_mappings(unsigned long start, unsigned long size,
 				  unsigned long phys, enum kvm_pgtable_prot prot)
 {