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>

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 0e66ebb49717509aa887a8053f1958ec8c172109..27864dfaeaaaba3d35080f06d91fb8326bc87d3e 100644 (file)
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -1961,10 +1961,11 @@ 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, int vector, PCIDevice *dev)
+int kvm_irqchip_add_msi_route(KVMRouteChange *c, int vector, PCIDevice *dev)
 {
     struct kvm_irq_routing_entry kroute = {};
     int virq;
+    KVMState *s = c->s;
     MSIMessage msg = {0, 0};
 
     if (pci_available && dev) {
@@ -2004,7 +2005,7 @@ int kvm_irqchip_add_msi_route(KVMState *s, int vector, PCIDevice *dev)
 
     kvm_add_routing_entry(s, &kroute);
     kvm_arch_add_msi_route_post(&kroute, vector, dev);
-    kvm_irqchip_commit_routes(s);
+    c->changes++;
 
     return virq;
 }
@@ -2162,7 +2163,7 @@ int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg)
     abort();
 }
 
-int kvm_irqchip_add_msi_route(KVMState *s, int vector, PCIDevice *dev)
+int kvm_irqchip_add_msi_route(KVMRouteChange *c, int vector, PCIDevice *dev)
 {
     return -ENOSYS;
 }

diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c
index 7e0fb884b937da8cd038bcf3c4bf8efa0d95e268..3345882d85d5041b74dbddbdfda3ef0048524c2e 100644 (file)
--- a/accel/stubs/kvm-stub.c
+++ b/accel/stubs/kvm-stub.c
@@ -77,7 +77,7 @@ int kvm_on_sigbus(int code, void *addr)
     return 1;
 }
 
-int kvm_irqchip_add_msi_route(KVMState *s, int vector, PCIDevice *dev)
+int kvm_irqchip_add_msi_route(KVMRouteChange *c, int vector, PCIDevice *dev)
 {
     return -ENOSYS;
 }

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 299837e5c13fa1f7f14d857ec36b0e6f4240703b..2307f4a5132f249a85ac1dd6e1919e1a7e6cd156 100644 (file)
--- 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 7b45353ce27ffb17d2ef4bcd7bdea18535f06d19..d07a4e99b1dba4598616d8c37e4b7beedde1f027 100644 (file)
--- 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 f9cf9592fdfaca35b4a81b26eb8182c90cc8e67c..7cf1231c1c5573cc3d5636cd6db53fd87593932b 100644 (file)
--- 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++;

diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 62772b5293b1b6242d53b31725a238075acea00a..a783c7886811621c53cd8227fb4eec4a85d78e3c 100644 (file)
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -486,7 +486,7 @@ void kvm_init_cpu_signals(CPUState *cpu);
 
 /**
  * kvm_irqchip_add_msi_route - Add MSI route for specific vector
- * @s:      KVM state
+ * @c:      KVMRouteChange instance.
  * @vector: which vector to add. This can be either MSI/MSIX
  *          vector. The function will automatically detect whether
  *          MSI/MSIX is enabled, and fetch corresponding MSI
@@ -495,7 +495,7 @@ void kvm_init_cpu_signals(CPUState *cpu);
  *          as @NULL, an empty MSI message will be inited.
  * @return: virq (>=0) when success, errno (<0) when failed.
  */
-int kvm_irqchip_add_msi_route(KVMState *s, int vector, PCIDevice *dev);
+int kvm_irqchip_add_msi_route(KVMRouteChange *c, int vector, PCIDevice *dev);
 int kvm_irqchip_update_msi_route(KVMState *s, int virq, MSIMessage msg,
                                  PCIDevice *dev);
 void kvm_irqchip_commit_routes(KVMState *s);

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 83d09883020325393834cfdc7912cdfc1788353a..31d467b5354e45b9b4065f9603d46642f14c32a8 100644 (file)
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -4940,16 +4940,18 @@ void kvm_arch_init_irq_routing(KVMState *s)
     kvm_gsi_routing_allowed = true;
 
     if (kvm_irqchip_is_split()) {
+        KVMRouteChange c = kvm_irqchip_begin_route_changes(s);
         int i;
 
         /* If the ioapic is in QEMU and the lapics are in KVM, reserve
            MSI routes for signaling interrupts to the local apics. */
         for (i = 0; i < IOAPIC_NUM_PINS; i++) {
-            if (kvm_irqchip_add_msi_route(s, 0, NULL) < 0) {
+            if (kvm_irqchip_add_msi_route(&c, 0, NULL) < 0) {
                 error_report("Could not enable split IRQ mode.");
                 exit(1);
             }
         }
+        kvm_irqchip_commit_route_changes(&c);
     }
 }