KVM: arm64: Add emulation for 32bit guests accessing ACTLR2

ACTLR_EL1 is a 64bit register while the 32bit ACTLR is obviously 32bit.
For 32bit software, the extra bits are accessible via ACTLR2... which
KVM doesn't emulate.

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200529150656.7339-3-james.morse@arm.com

arch/arm64/kvm/sys_regs_generic_v8.c

@@ -27,6 +27,14 @@ static bool access_actlr(struct kvm_vcpu *vcpu,
 		return ignore_write(vcpu, p);
 
 	p->regval = vcpu_read_sys_reg(vcpu, ACTLR_EL1);
+
+	if (p->is_aarch32) {
+		if (r->Op2 & 2)
+			p->regval = upper_32_bits(p->regval);
+		else
+			p->regval = lower_32_bits(p->regval);
+	}
+
 	return true;
 }
 
@@ -47,6 +55,8 @@ static const struct sys_reg_desc genericv8_cp15_regs[] = {
 	/* ACTLR */
 	{ Op1(0b000), CRn(0b0001), CRm(0b0000), Op2(0b001),
 	  access_actlr },
+	{ Op1(0b000), CRn(0b0001), CRm(0b0000), Op2(0b011),
+	  access_actlr },
 };
 
 static struct kvm_sys_reg_target_table genericv8_target_table = {