arm64: alternatives: kvm: prepare for cap changes

The KVM patching callbacks use cpus_have_final_cap() internally within
has_vhe(), and subsequent patches will make it invalid to call
cpus_have_final_cap() before alternatives patching has completed, and
will mean that cpus_have_const_cap() will always fall back to dynamic
checks prior to alternatives patching.

In preparation for said change, this patch modifies the KVM patching
callbacks to use cpus_have_cap() directly. This is not subject to
patching, and will dynamically check the cpu_hwcaps array, which is
functionally equivalent to the existing behaviour.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220912162210.3626215-3-mark.rutland@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kvm/va_layout.c

@@ -169,7 +169,7 @@ void __init kvm_update_va_mask(struct alt_instr *alt,
 		 * dictates it and we don't have any spare bits in the
 		 * address), NOP everything after masking the kernel VA.
 		 */
-		if (has_vhe() || (!tag_val && i > 0)) {
+		if (cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN) || (!tag_val && i > 0)) {
 			updptr[i] = cpu_to_le32(aarch64_insn_gen_nop());
 			continue;
 		}
@@ -193,7 +193,8 @@ void kvm_patch_vector_branch(struct alt_instr *alt,
 
 	BUG_ON(nr_inst != 4);
 
-	if (!cpus_have_const_cap(ARM64_SPECTRE_V3A) || WARN_ON_ONCE(has_vhe()))
+	if (!cpus_have_cap(ARM64_SPECTRE_V3A) ||
+	    WARN_ON_ONCE(cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN)))
 		return;
 
 	/*