[Qemu-devel] [PATCH 1/2] kvm irqfd: support msimessage to irq translation in PHB

[Alexey Kardashevskiy]

On PPC64 systems MSI Messages are translated to system IRQ in a PCI
host bridge. This is already supported for emulated MSI/MSIX but
not for irqfd where the current QEMU allocates IRQ numbers from
irqchip and maps MSIMessages to those IRQ in the host kernel.

The patch extends irqfd support in order to avoid unnecessary
mapping and reuse the one which already exists in a PCI host bridge.

Specifically, a map_msi callback is added to PCIBus and pci_bus_map_msi()
to PCI API. The latter tries a bus specific map_msi and falls back to
the default kvm_irqchip_add_msi_route() if none set.

Signed-off-by: Alexey Kardashevskiy <address@hidden>

---
Changes:
2013/08/07 v5:
* pci_bus_map_msi now has default behaviour which is to call
kvm_irqchip_add_msi_route
* kvm_irqchip_release_virq fixed not crash when there is no routes
---
 hw/i386/kvm/pci-assign.c | 4 ++--
 hw/misc/vfio.c           | 4 ++--
 hw/pci/pci.c             | 9 +++++++++
 hw/virtio/virtio-pci.c   | 2 +-
 include/hw/pci/pci.h     | 2 ++
 include/hw/pci/pci_bus.h | 1 +
 kvm-all.c                | 3 +++
 7 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/hw/i386/kvm/pci-assign.c b/hw/i386/kvm/pci-assign.c
index 5618173..fb59982 100644
--- a/hw/i386/kvm/pci-assign.c
+++ b/hw/i386/kvm/pci-assign.c
@@ -1008,9 +1008,9 @@ static void assigned_dev_update_msi(PCIDevice *pci_dev)
         MSIMessage msg = msi_get_message(pci_dev, 0);
         int virq;
 
-        virq = kvm_irqchip_add_msi_route(kvm_state, msg);
+        virq = pci_bus_map_msi(kvm_state, pci_dev->bus, msg);
         if (virq < 0) {
-            perror("assigned_dev_update_msi: kvm_irqchip_add_msi_route");
+            perror("assigned_dev_update_msi: pci_bus_map_msi");
             return;
         }
 
diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index 017e693..adcd23d 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -643,7 +643,7 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
      * Attempt to enable route through KVM irqchip,
      * default to userspace handling if unavailable.
      */
-    vector->virq = msg ? kvm_irqchip_add_msi_route(kvm_state, *msg) : -1;
+    vector->virq = msg ? pci_bus_map_msi(kvm_state, vdev->pdev.bus, *msg) : -1;
     if (vector->virq < 0 ||
         kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
                                        vector->virq) < 0) {
@@ -811,7 +811,7 @@ retry:
          * Attempt to enable route through KVM irqchip,
          * default to userspace handling if unavailable.
          */
-        vector->virq = kvm_irqchip_add_msi_route(kvm_state, msg);
+        vector->virq = pci_bus_map_msi(kvm_state, vdev->pdev.bus, msg);
         if (vector->virq < 0 ||
             kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
                                            vector->virq) < 0) {
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 4c004f5..4bce3e7 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -1249,6 +1249,15 @@ void pci_device_set_intx_routing_notifier(PCIDevice *dev,
     dev->intx_routing_notifier = notifier;
 }
 
+int pci_bus_map_msi(KVMState *s, PCIBus *bus, MSIMessage msg)
+{
+    if (bus->map_msi) {
+        return bus->map_msi(s, bus, msg);
+    }
+
+    return kvm_irqchip_add_msi_route(s, msg);
+}
+
 /*
  * PCI-to-PCI bridge specification
  * 9.1: Interrupt routing. Table 9-1
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index d37037e..21180d2 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -481,7 +481,7 @@ static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy 
*proxy,
     int ret;
 
     if (irqfd->users == 0) {
-        ret = kvm_irqchip_add_msi_route(kvm_state, msg);
+        ret = pci_bus_map_msi(kvm_state, proxy->pci_dev.bus, msg);
         if (ret < 0) {
             return ret;
         }
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index ccec2ba..b6ad9e4 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -332,6 +332,7 @@ MemoryRegion *pci_address_space_io(PCIDevice *dev);
 typedef void (*pci_set_irq_fn)(void *opaque, int irq_num, int level);
 typedef int (*pci_map_irq_fn)(PCIDevice *pci_dev, int irq_num);
 typedef PCIINTxRoute (*pci_route_irq_fn)(void *opaque, int pin);
+typedef int (*pci_map_msi_fn)(KVMState *s, PCIBus *bus, MSIMessage msg);
 
 typedef enum {
     PCI_HOTPLUG_DISABLED,
@@ -375,6 +376,7 @@ bool pci_intx_route_changed(PCIINTxRoute *old, PCIINTxRoute 
*new);
 void pci_bus_fire_intx_routing_notifier(PCIBus *bus);
 void pci_device_set_intx_routing_notifier(PCIDevice *dev,
                                           PCIINTxRoutingNotifier notifier);
+int pci_bus_map_msi(KVMState *s, PCIBus *bus, MSIMessage msg);
 void pci_device_reset(PCIDevice *dev);
 void pci_bus_reset(PCIBus *bus);
 
diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
index 9df1788..5bf7994 100644
--- a/include/hw/pci/pci_bus.h
+++ b/include/hw/pci/pci_bus.h
@@ -16,6 +16,7 @@ struct PCIBus {
     pci_set_irq_fn set_irq;
     pci_map_irq_fn map_irq;
     pci_route_irq_fn route_intx_to_irq;
+    pci_map_msi_fn map_msi;
     pci_hotplug_fn hotplug;
     DeviceState *hotplug_qdev;
     void *irq_opaque;
diff --git a/kvm-all.c b/kvm-all.c
index 716860f..3ae5274 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1069,6 +1069,9 @@ void kvm_irqchip_release_virq(KVMState *s, int virq)
     struct kvm_irq_routing_entry *e;
     int i;
 
+    if (!s->irq_routes) {
+        return;
+    }
     for (i = 0; i < s->irq_routes->nr; i++) {
         e = &s->irq_routes->entries[i];
         if (e->gsi == virq) {
-- 
1.8.3.2