KVM: PPC: Book3S HV: Implement LPCR[AIL]=3 mode for injected interrupts

kvmppc_inject_interrupt does not implement LPCR[AIL]!=0 modes, which
can result in the guest receiving interrupts as if LPCR[AIL]=0
contrary to the ISA.

In practice, Linux guests cope with this deviation, but it should be
fixed.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/kvm/book3s_hv_builtin.c

@@ -792,6 +792,21 @@ static void inject_interrupt(struct kvm_vcpu *vcpu, int vec, u64 srr1_flags)
 	else
 		new_msr |= msr & MSR_TS_MASK;
 
+	/*
+	 * Perform MSR and PC adjustment for LPCR[AIL]=3 if it is set and
+	 * applicable. AIL=2 is not supported.
+	 *
+	 * AIL does not apply to SRESET, MCE, or HMI (which is never
+	 * delivered to the guest), and does not apply if IR=0 or DR=0.
+	 */
+	if (vec != BOOK3S_INTERRUPT_SYSTEM_RESET &&
+	    vec != BOOK3S_INTERRUPT_MACHINE_CHECK &&
+	    (vcpu->arch.vcore->lpcr & LPCR_AIL) == LPCR_AIL_3 &&
+	    (msr & (MSR_IR|MSR_DR)) == (MSR_IR|MSR_DR) ) {
+		new_msr |= MSR_IR | MSR_DR;
+		new_pc += 0xC000000000004000ULL;
+	}
+
 	kvmppc_set_srr0(vcpu, pc);
 	kvmppc_set_srr1(vcpu, (msr & SRR1_MSR_BITS) | srr1_flags);
 	kvmppc_set_pc(vcpu, new_pc);