KVM: arm64: Make BP hardening globals static instead

Branch predictor hardening of the hyp vectors is partially driven by a
couple of global variables ('__kvm_bp_vect_base' and
'__kvm_harden_el2_vector_slot'). However, these are only used within a
single compilation unit, so internalise them there instead.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20201113113847.21619-5-will@kernel.org

Author: willdeacon

arch/arm64/include/asm/kvm_mmu.h

@@ -208,9 +208,6 @@ static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa,
 	return ret;
 }
 
-extern void *__kvm_bp_vect_base;
-extern int __kvm_harden_el2_vector_slot;
-
 #define kvm_phys_to_vttbr(addr)		phys_to_ttbr(addr)
 
 static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu)

arch/arm64/kvm/arm.c

@@ -51,6 +51,14 @@ DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector);
 static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
 unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
 
+/* Hypervisor VA of the indirect vector trampoline page */
+static void *__kvm_bp_vect_base;
+/*
+ * Slot in the hyp vector page for use by the indirect vector trampoline
+ * when mitigation against Spectre-v2 is not required.
+ */
+static int __kvm_harden_el2_vector_slot;
+
 /* The VMID used in the VTTBR */
 static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1);
 static u32 kvm_next_vmid;

arch/arm64/kvm/va_layout.c

@@ -131,9 +131,6 @@ void __init kvm_update_va_mask(struct alt_instr *alt,
 	}
 }
 
-void *__kvm_bp_vect_base;
-int __kvm_harden_el2_vector_slot;
-
 void kvm_patch_vector_branch(struct alt_instr *alt,
 			     __le32 *origptr, __le32 *updptr, int nr_inst)
 {