KVM: arm64: Factor out vector address calculation

In order to re-map the guest vectors at EL2 when pKVM is enabled,
refactor __kvm_vector_slot2idx() and kvm_init_vector_slot() to move all
the address calculation logic in a static inline function.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-16-qperret@google.com

arch/arm64/include/asm/kvm_mmu.h

@@ -168,6 +168,14 @@ phys_addr_t kvm_mmu_get_httbr(void);
 phys_addr_t kvm_get_idmap_vector(void);
 int kvm_mmu_init(void);
 
+static inline void *__kvm_vector_slot2addr(void *base,
+					   enum arm64_hyp_spectre_vector slot)
+{
+	int idx = slot - (slot != HYP_VECTOR_DIRECT);
+
+	return base + (idx * SZ_2K);
+}
+
 struct kvm;
 
 #define kvm_flush_dcache_to_poc(a,l)	__flush_dcache_area((a), (l))

arch/arm64/kvm/arm.c

@@ -1350,16 +1350,9 @@ static unsigned long nvhe_percpu_order(void)
 /* A lookup table holding the hypervisor VA for each vector slot */
 static void *hyp_spectre_vector_selector[BP_HARDEN_EL2_SLOTS];
 
-static int __kvm_vector_slot2idx(enum arm64_hyp_spectre_vector slot)
-{
-	return slot - (slot != HYP_VECTOR_DIRECT);
-}
-
 static void kvm_init_vector_slot(void *base, enum arm64_hyp_spectre_vector slot)
 {
-	int idx = __kvm_vector_slot2idx(slot);
-
-	hyp_spectre_vector_selector[slot] = base + (idx * SZ_2K);
+	hyp_spectre_vector_selector[slot] = __kvm_vector_slot2addr(base, slot);
 }
 
 static int kvm_init_vector_slots(void)