From: Stanislav Kinsburskii <[email protected]> Sent: Monday,
February 23, 2026 11:40 AM
>
[snip]
> > +
> > +static int __init mshv_sint_vector_init(void)
> > +{
> > + int ret;
> > + struct hv_register_assoc reg = {
> > + .name = HV_ARM64_REGISTER_SINT_RESERVED_INTERRUPT_ID,
> > + };
> > + union hv_input_vtl input_vtl = { 0 };
> > +
> > + if (acpi_disabled)
> > + return -ENODEV;
> > +
> > + ret = hv_call_get_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
> > + 1, input_vtl, ®);
> > + if (ret || !reg.value.reg64)
> > + return -ENODEV;
> > +
> > + mshv_sint_vector = reg.value.reg64;
> > + ret = mshv_acpi_setup_sint_irq();
> > + if (ret <= 0) {
> > + pr_err("Failed to setup IRQ for MSHV SINT vector %d: %d\n",
> > + mshv_sint_vector, ret);
> > + goto out_fail;
> > + }
> > +
> > + mshv_sint_irq = ret;
>
> nit: given that mshv_sint_irq can't be zero, the logic can be simplified by
> using 0 instead of -1.
The test for <= 0 is actually wrong -- it should be just < 0. Zero is a valid
Linux IRQ number. For example, here's the output of /proc/interrupts on
a Gen1 VM on Hyper-V, where IRQ 0 is used by the legacy timer:
root@gen1ubun:~# cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3
0: 18 0 0 0 IR-IO-APIC 2-edge timer
1: 0 9 0 0 IR-IO-APIC 1-edge i8042
4: 0 0 0 792 IR-IO-APIC 4-edge ttyS0
6: 6 0 0 0 IR-IO-APIC 6-edge floppy
8: 0 0 0 0 IR-IO-APIC 8-edge rtc0
9: 0 0 0 0 IR-IO-APIC 9-fasteoi acpi
But I see other places throughout Linux kernel code that treat IRQ 0 as
invalid. So I dunno .... But it's probably better to treat 0 as a valid IRQ
number.
Michael
>
>
>
> > +
> > + ret = request_percpu_irq(mshv_sint_irq, mshv_percpu_isr, "MSHV",
> > + &mshv_evt);
> > + if (ret)
> > + goto out_unregister;
> > +
> > + return 0;
> > +
> > +out_unregister:
> > + mshv_acpi_cleanup_sint_irq();
> > +out_fail:
> > + return ret;
> > +}
> > +
> > +static void mshv_sint_vector_cleanup(void)
> > +{
> > + free_percpu_irq(mshv_sint_irq, &mshv_evt);
> > + mshv_acpi_cleanup_sint_irq();
> > +}
> > +#else /* !HYPERVISOR_CALLBACK_VECTOR */
> > +static int __init mshv_sint_vector_init(void)
>
> nit: `init` is usually paired with `exit` or `fini`, so maybe `cleanup` can be
> renamed to `exit` as well for better consistency?
>
> Reviewed-by: Stanislav Kinsburskii <[email protected]>
>
> > +{
> > + mshv_sint_vector = HYPERVISOR_CALLBACK_VECTOR;
> > + return 0;
> > +}
> > +
> > +static void mshv_sint_vector_cleanup(void)
> > +{
> > +}
> > +#endif /* HYPERVISOR_CALLBACK_VECTOR */
> > +
> > int __init mshv_synic_init(struct device *dev)
> > {
> > int ret = 0;
> >
> > + ret = mshv_sint_vector_init();
> > + if (ret)
> > + return ret;
> > +
> > synic_pages = alloc_percpu(struct hv_synic_pages);
> > if (!synic_pages) {
> > dev_err(dev, "Failed to allocate percpu synic page\n");
> > - return -ENOMEM;
> > + ret = -ENOMEM;
> > + goto sint_vector_cleanup;
> > }
> >
> > ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mshv_synic",
> > @@ -713,6 +810,8 @@ int __init mshv_synic_init(struct device *dev)
> > cpuhp_remove_state(synic_cpuhp_online);
> > free_synic_pages:
> > free_percpu(synic_pages);
> > +sint_vector_cleanup:
> > + mshv_sint_vector_cleanup();
> > return ret;
> > }
> >
> > @@ -721,4 +820,5 @@ void mshv_synic_cleanup(void)
> > unregister_reboot_notifier(&mshv_synic_reboot_nb);
> > cpuhp_remove_state(synic_cpuhp_online);
> > free_percpu(synic_pages);
> > + mshv_sint_vector_cleanup();
> > }
> > diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
> > index 30fbbde81c5c..7676f78e0766 100644
> > --- a/include/hyperv/hvgdk_mini.h
> > +++ b/include/hyperv/hvgdk_mini.h
> > @@ -1117,6 +1117,8 @@ enum hv_register_name {
> > HV_X64_REGISTER_MSR_MTRR_FIX4KF8000 = 0x0008007A,
> >
> > HV_X64_REGISTER_REG_PAGE = 0x0009001C,
> > +#elif defined(CONFIG_ARM64)
> > + HV_ARM64_REGISTER_SINT_RESERVED_INTERRUPT_ID = 0x00070001,
> > #endif
> > };
> >
> > --
> > 2.34.1
> >
