Method update

vmm/src/interrupt.rs:243–295

(
        &self,
        index: InterruptIndex,
        config: InterruptSourceConfig,
        masked: bool,
        set_gsi: bool,
    )

    }

    fn update(
        &self,
        index: InterruptIndex,
        config: InterruptSourceConfig,
        masked: bool,
        set_gsi: bool,
    ) -> Result<()> {
        if let Some(route) = self.irq_routes.get(&index) {
            let mut route = route.lock().unwrap();
            let gsi = if masked {
                match route.gsi {
                    Some(gsi) => gsi,
                    // No update needed if masked and no GSI was ever allocated
                    None => return Ok(()),
                }
            } else {
                // Allocate a GSI when the interrupt vector is first unmasked
                route.allocate_gsi()?
            };

            let entry = RoutingEntry {
                route: self.vm.make_routing_entry(gsi, &config),
                masked,
            };

            // When mask a msi irq, entry.masked is set to be true,
            // and the gsi will not be passed to KVM through KVM_SET_GSI_ROUTING.
            // So it's required to call disable() (which deassign KVM_IRQFD) before
            // set_gsi_routes() to avoid kernel panic (see #3827)
            if masked {
                route.disable(self.vm.as_ref())?;
            }

            let mut routes = self.gsi_msi_routes.lock().unwrap();
            routes.insert(gsi, entry);
            if set_gsi {
                self.set_gsi_routes(&routes)?;
            }

            // Assign KVM_IRQFD after KVM_SET_GSI_ROUTING to avoid
            // panic on kernel which not have commit a80ced6ea514
            // (KVM: SVM: fix panic on out-of-bounds guest IRQ).
            if !masked {
                route.enable(self.vm.as_ref())?;
            }

            return Ok(());
        }

        Err(io::Error::other(format!(
            "update: Invalid interrupt index {index}"
        )))
    }

    fn set_gsi(&self) -> Result<()> {
        let routes = self.gsi_msi_routes.lock().unwrap();