RISC-V: KVM: Don't setup SGEI for zero guest external interrupts

No need to setup SGEI local interrupt when there are zero guest
external interrupts (i.e. zero HW IMSIC guest files).

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20241020194734.58686-7-apatel@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>

Author: avpatel

arch/riscv/kvm/aia.c

@@ -499,6 +499,10 @@ static int aia_hgei_init(void)
 			hgctrl->free_bitmap = 0;
 	}
 
+	/* Skip SGEI interrupt setup for zero guest external interrupts */
+	if (!kvm_riscv_aia_nr_hgei)
+		goto skip_sgei_interrupt;
+
 	/* Find INTC irq domain */
 	domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(),
 					  DOMAIN_BUS_ANY);
@@ -522,11 +526,16 @@ static int aia_hgei_init(void)
 		return rc;
 	}
 
+skip_sgei_interrupt:
 	return 0;
 }
 
 static void aia_hgei_exit(void)
 {
+	/* Do nothing for zero guest external interrupts */
+	if (!kvm_riscv_aia_nr_hgei)
+		return;
+
 	/* Free per-CPU SGEI interrupt */
 	free_percpu_irq(hgei_parent_irq, &aia_hgei);
 }