vfio/pci: Respond to KVM irqchip change notifier

VFIO PCI devices already respond to the pci intx routing notifier, in order
to update kernel irqchip mappings when routing is updated.  However this
won't handle the case where the irqchip itself is replaced by a different
model while retaining the same routing.  This case can happen on
the pseries machine type due to PAPR feature negotiation.

To handle that case, add a handler for the irqchip change notifier, which
does much the same thing as the routing notifier, but is unconditional,
rather than being a no-op when the routing hasn't changed.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Acked-by: Alex Williamson <alex.williamson@redhat.com>

2 files changed, 20 insertions, 6 deletions

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 521289a..2d40b39 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -256,6 +256,14 @@ static void vfio_intx_routing_notifier(PCIDevice *pdev)
     }
 }
 
+static void vfio_irqchip_change(Notifier *notify, void *data)
+{
+    VFIOPCIDevice *vdev = container_of(notify, VFIOPCIDevice,
+                                       irqchip_change_notifier);
+
+    vfio_intx_update(vdev, &vdev->intx.route);
+}
+
 static int vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
 {
     uint8_t pin = vfio_pci_read_config(&vdev->pdev, PCI_INTERRUPT_PIN, 1);
@@ -2973,30 +2981,32 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
                                                   vfio_intx_mmap_enable, vdev);
         pci_device_set_intx_routing_notifier(&vdev->pdev,
                                              vfio_intx_routing_notifier);
+        vdev->irqchip_change_notifier.notify = vfio_irqchip_change;
+        kvm_irqchip_add_change_notifier(&vdev->irqchip_change_notifier);
         ret = vfio_intx_enable(vdev, errp);
         if (ret) {
-            goto out_teardown;
+            goto out_deregister;
         }
     }
 
     if (vdev->display != ON_OFF_AUTO_OFF) {
         ret = vfio_display_probe(vdev, errp);
         if (ret) {
-            goto out_teardown;
+            goto out_deregister;
         }
     }
     if (vdev->enable_ramfb && vdev->dpy == NULL) {
         error_setg(errp, "ramfb=on requires display=on");
-        goto out_teardown;
+        goto out_deregister;
     }
     if (vdev->display_xres || vdev->display_yres) {
         if (vdev->dpy == NULL) {
             error_setg(errp, "xres and yres properties require display=on");
-            goto out_teardown;
+            goto out_deregister;
         }
         if (vdev->dpy->edid_regs == NULL) {
             error_setg(errp, "xres and yres properties need edid support");
-            goto out_teardown;
+            goto out_deregister;
         }
     }
 
@@ -3020,8 +3030,10 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
 
     return;
 
-out_teardown:
+out_deregister:
     pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
+    kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
+out_teardown:
     vfio_teardown_msi(vdev);
     vfio_bars_exit(vdev);
 error:
@@ -3064,6 +3076,7 @@ static void vfio_exitfn(PCIDevice *pdev)
     vfio_unregister_req_notifier(vdev);
     vfio_unregister_err_notifier(vdev);
     pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
+    kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
     vfio_disable_interrupts(vdev);
     if (vdev->intx.mmap_timer) {
         timer_free(vdev->intx.mmap_timer);
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index b329d50..35626cd 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -169,6 +169,7 @@ typedef struct VFIOPCIDevice {
     bool enable_ramfb;
     VFIODisplay *dpy;
     Error *migration_blocker;
+    Notifier irqchip_change_notifier;
 } VFIOPCIDevice;
 
 uint32_t vfio_pci_read_config(PCIDevice *pdev, uint32_t addr, int len);