[Qemu-devel] [PATCH] RFCv3 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 returns -1 if a specific PHB does not provide
with any trsnslation so the existing code will work.

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

---

Looks like we agreed that in general PHB is the right place for this,
not KVM, so I am trying again.

Probably something should be done to kvm_irqchip_update_msi_route()
as well but I do not really understand what exactly. Any suggestions?


---
 hw/misc/vfio.c           |    7 +++++--
 hw/pci/pci.c             |   13 +++++++++++++
 hw/ppc/spapr_pci.c       |    6 ++++++
 hw/virtio/virtio-pci.c   |    2 +-
 include/hw/pci/pci.h     |    4 ++++
 include/hw/pci/pci_bus.h |    1 +
 include/sysemu/kvm.h     |    2 +-
 kvm-all.c                |    7 ++++++-
 8 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index 52fb036..59911bb 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -624,7 +624,9 @@ 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 ?
+            kvm_irqchip_add_msi_route(kvm_state, vdev->pdev.bus, *msg) : -1;
     if (vector->virq < 0 ||
         kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
                                        vector->virq) < 0) {
@@ -792,7 +794,8 @@ 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 = kvm_irqchip_add_msi_route(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 61b681a..543f172 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -1240,6 +1240,19 @@ void pci_device_set_intx_routing_notifier(PCIDevice *dev,
     dev->intx_routing_notifier = notifier;
 }
 
+void pci_bus_set_map_msi_fn(PCIBus *bus, pci_map_msi_fn map_msi_fn)
+{
+    bus->map_msi = map_msi_fn;
+}
+
+int pci_bus_map_msi(PCIBus *bus, MSIMessage msg)
+{
+    if (bus->map_msi) {
+        return bus->map_msi(bus, msg);
+    }
+    return -1;
+}
+
 /*
  * PCI-to-PCI bridge specification
  * 9.1: Interrupt routing. Table 9-1
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 23dbc0e..bae4faf 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -486,6 +486,11 @@ static void spapr_msi_write(void *opaque, hwaddr addr,
     qemu_irq_pulse(xics_get_qirq(spapr->icp, irq));
 }
 
+static int spapr_msi_get_irq(PCIBus *bus, MSIMessage msg)
+{
+    return msg.data;
+}
+
 static const MemoryRegionOps spapr_msi_ops = {
     /* There is no .read as the read result is undefined by PCI spec */
     .read = NULL,
@@ -657,6 +662,7 @@ static int spapr_phb_init(SysBusDevice *s)
 
         sphb->lsi_table[i].irq = irq;
     }
+    pci_bus_set_map_msi_fn(bus, spapr_msi_get_irq);
 
     return 0;
 }
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index b070b64..06a4e13 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 = kvm_irqchip_add_msi_route(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 6ef1f97..8c1edd6 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)(PCIBus *bus, MSIMessage msg);
 
 typedef enum {
     PCI_HOTPLUG_DISABLED,
@@ -375,6 +376,9 @@ 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);
+void pci_bus_set_map_msi_fn(PCIBus *bus, pci_map_msi_fn map_msi_fn);
+int pci_bus_map_msi(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 66762f6..81efd2b 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/include/sysemu/kvm.h b/include/sysemu/kvm.h
index f404d16..1bf2abe 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -305,8 +305,8 @@ static inline void cpu_synchronize_post_init(CPUState *cpu)
     }
 }
 
-int kvm_irqchip_add_msi_route(KVMState *s, MSIMessage msg);
 int kvm_irqchip_update_msi_route(KVMState *s, int virq, MSIMessage msg);
+int kvm_irqchip_add_msi_route(KVMState *s, PCIBus *pbus, MSIMessage msg);
 void kvm_irqchip_release_virq(KVMState *s, int virq);
 
 int kvm_irqchip_add_irqfd_notifier(KVMState *s, EventNotifier *n, int virq);
diff --git a/kvm-all.c b/kvm-all.c
index 1f81cca..3b7710d 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1180,11 +1180,16 @@ int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg)
     return kvm_set_irq(s, route->kroute.gsi, 1);
 }
 
-int kvm_irqchip_add_msi_route(KVMState *s, MSIMessage msg)
+int kvm_irqchip_add_msi_route(KVMState *s, PCIBus *pbus, MSIMessage msg)
 {
     struct kvm_irq_routing_entry kroute;
     int virq;
 
+    virq = pci_bus_map_msi(pbus, msg);
+    if (virq >= 0) {
+        return virq;
+    }
+
     if (!kvm_gsi_routing_enabled()) {
         return -ENOSYS;
     }
-- 
1.7.10.4