The gsi of a passthrough device must be configured for it to be able to be mapped into a hvm domU. But When dom0 is PVH, the gsis don't get registered, it causes the info of apic, pin and irq not be added into irq_2_pin list, and the handler of irq_desc is not set, then when passthrough a device, setting ioapic affinity and vector will fail.
To fix above problem, on Linux kernel side, a new code will need to call PHYSDEVOP_setup_gsi for passthrough devices to register gsi when dom0 is PVH. So, add PHYSDEVOP_setup_gsi into hvm_physdev_op for above purpose. Clarify two questions: First, why the gsi of devices belong to PVH dom0 can work? Because when probe a driver to a normal device, it calls(on linux kernel side) pci_device_probe-> request_threaded_irq-> irq_startup-> __unmask_ioapic-> io_apic_write, then trap into xen side hvmemul_do_io-> hvm_io_intercept-> hvm_process_io_intercept-> vioapic_write_indirect-> vioapic_hwdom_map_gsi-> mp_register_gsi. So that the gsi can be registered. Second, why the gsi of passthrough device can't work when dom0 is PVH? Because when assign a device to passthrough, it uses pciback to probe the device, and it calls pcistub_probe->pcistub_seize-> pcistub_init_device-> xen_pcibk_reset_device-> xen_pcibk_control_isr->isr_on, but isr_on is not set, so that the fake IRQ handler is not installed, then the gsi isn't unmasked. What's more, we can see on Xen side, the function vioapic_hwdom_map_gsi-> mp_register_gsi will be called only when the gsi is unmasked, so that the gsi can't work for passthrough device. Signed-off-by: Jiqian Chen <[email protected]> Signed-off-by: Huang Rui <[email protected]> Signed-off-by: Jiqian Chen <[email protected]> --- xen/arch/x86/hvm/hypercall.c | 1 + 1 file changed, 1 insertion(+) diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c index 03ada3c880bd..cfe82d0f96ed 100644 --- a/xen/arch/x86/hvm/hypercall.c +++ b/xen/arch/x86/hvm/hypercall.c @@ -86,6 +86,7 @@ long hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg) return -ENOSYS; break; + case PHYSDEVOP_setup_gsi: case PHYSDEVOP_pci_mmcfg_reserved: case PHYSDEVOP_pci_device_add: case PHYSDEVOP_pci_device_remove: -- 2.34.1
