KVM: arm64: Remove redundant hyp vectors entry

The hyp vectors entry corresponding to HYP_VECTOR_DIRECT (i.e. when
neither Spectre-v2 nor Spectre-v3a are present) is unused, as we can
simply dispatch straight to __kvm_hyp_vector in this case.

Remove the redundant vector, and massage the logic for resolving a slot
to a vectors entry.
Reported-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201113113847.21619-11-will@kernel.org

arch/arm64/include/asm/spectre.h

@@ -10,7 +10,7 @@
 #define __ASM_SPECTRE_H
 
 #define BP_HARDEN_EL2_SLOTS 4
-#define __BP_HARDEN_HYP_VECS_SZ (BP_HARDEN_EL2_SLOTS * SZ_2K)
+#define __BP_HARDEN_HYP_VECS_SZ	((BP_HARDEN_EL2_SLOTS - 1) * SZ_2K)
 
 #ifndef __ASSEMBLY__
 

arch/arm64/kvm/arm.c

@@ -1298,9 +1298,16 @@ 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)
 {
-	hyp_spectre_vector_selector[slot] = base + (slot * SZ_2K);
+	int idx = __kvm_vector_slot2idx(slot);
+
+	hyp_spectre_vector_selector[slot] = base + (idx * SZ_2K);
 }
 
 static int kvm_init_vector_slots(void)

arch/arm64/kvm/hyp/hyp-entry.S

@@ -239,7 +239,6 @@ SYM_CODE_END(__kvm_hyp_vector)
 
 	.align	11
 SYM_CODE_START(__bp_harden_hyp_vecs)
-	generate_vectors indirect = 0, spectrev2 = 0 // HYP_VECTOR_DIRECT
 	generate_vectors indirect = 0, spectrev2 = 1 // HYP_VECTOR_SPECTRE_DIRECT
 	generate_vectors indirect = 1, spectrev2 = 0 // HYP_VECTOR_INDIRECT
 	generate_vectors indirect = 1, spectrev2 = 1 // HYP_VECTOR_SPECTRE_INDIRECT