kvm/msi: do explicit commit when adding msi routes

We invoke the kvm_irqchip_commit_routes() for each addition to MSI route
table, which is not efficient if we are adding lots of routes in some cases.

This patch lets callers invoke the kvm_irqchip_commit_routes(), so the
callers can decide how to optimize.

[1] https://lists.gnu.org/archive/html/qemu-devel/2021-11/msg00967.html

Signed-off-by: Longpeng <longpeng2@huawei.com>
Message-Id: <20220222141116.2091-3-longpeng2@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 11 insertions, 3 deletions

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 299837e..2307f4a 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -424,16 +424,19 @@ static void ivshmem_add_kvm_msi_virq(IVShmemState *s, int vector,
                                      Error **errp)
 {
     PCIDevice *pdev = PCI_DEVICE(s);
+    KVMRouteChange c;
     int ret;
 
     IVSHMEM_DPRINTF("ivshmem_add_kvm_msi_virq vector:%d\n", vector);
     assert(!s->msi_vectors[vector].pdev);
 
-    ret = kvm_irqchip_add_msi_route(kvm_state, vector, pdev);
+    c = kvm_irqchip_begin_route_changes(kvm_state);
+    ret = kvm_irqchip_add_msi_route(&c, vector, pdev);
     if (ret < 0) {
         error_setg(errp, "kvm_irqchip_add_msi_route failed");
         return;
     }
+    kvm_irqchip_commit_route_changes(&c);
 
     s->msi_vectors[vector].virq = ret;
     s->msi_vectors[vector].pdev = pdev;
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 7b45353..d07a4e9 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -412,6 +412,7 @@ static int vfio_enable_vectors(VFIOPCIDevice *vdev, bool msix)
 static void vfio_add_kvm_msi_virq(VFIOPCIDevice *vdev, VFIOMSIVector *vector,
                                   int vector_n, bool msix)
 {
+    KVMRouteChange c;
     int virq;
 
     if ((msix && vdev->no_kvm_msix) || (!msix && vdev->no_kvm_msi)) {
@@ -422,11 +423,13 @@ static void vfio_add_kvm_msi_virq(VFIOPCIDevice *vdev, VFIOMSIVector *vector,
         return;
     }
 
-    virq = kvm_irqchip_add_msi_route(kvm_state, vector_n, &vdev->pdev);
+    c = kvm_irqchip_begin_route_changes(kvm_state);
+    virq = kvm_irqchip_add_msi_route(&c, vector_n, &vdev->pdev);
     if (virq < 0) {
         event_notifier_cleanup(&vector->kvm_interrupt);
         return;
     }
+    kvm_irqchip_commit_route_changes(&c);
 
     if (kvm_irqchip_add_irqfd_notifier_gsi(kvm_state, &vector->kvm_interrupt,
                                        NULL, virq) < 0) {
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index f9cf959..7cf1231 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -683,10 +683,12 @@ static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
     int ret;
 
     if (irqfd->users == 0) {
-        ret = kvm_irqchip_add_msi_route(kvm_state, vector, &proxy->pci_dev);
+        KVMRouteChange c = kvm_irqchip_begin_route_changes(kvm_state);
+        ret = kvm_irqchip_add_msi_route(&c, vector, &proxy->pci_dev);
         if (ret < 0) {
             return ret;
         }
+        kvm_irqchip_commit_route_changes(&c);
         irqfd->virq = ret;
     }
     irqfd->users++;