From 7d37d351dffee60fc7048bbfd8573421f15eb724 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Thu, 17 May 2012 10:32:39 -0300 Subject: virtio/vhost: Add support for KVM in-kernel MSI injection Make use of the new vector notifier to track changes of the MSI-X configuration of virtio PCI devices. On enabling events, we establish the required virtual IRQ to MSI-X message route and link the signaling eventfd file descriptor to this vIRQ line. That way, vhost-generated interrupts can be directly delivered to an in-kernel MSI-X consumer like the x86 APIC. Signed-off-by: Jan Kiszka Signed-off-by: Avi Kivity --- hw/virtio-pci.c | 126 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 126 insertions(+) (limited to 'hw/virtio-pci.c') diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index 4a4413d52c..01f5b92b1c 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -24,6 +24,7 @@ #include "virtio-scsi.h" #include "pci.h" #include "qemu-error.h" +#include "msi.h" #include "msix.h" #include "net.h" #include "loader.h" @@ -539,6 +540,107 @@ static void virtio_pci_guest_notifier_read(void *opaque) } } +static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy, + unsigned int queue_no, + unsigned int vector, + MSIMessage msg) +{ + VirtQueue *vq = virtio_get_queue(proxy->vdev, queue_no); + VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector]; + int fd, ret; + + fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vq)); + + if (irqfd->users == 0) { + ret = kvm_irqchip_add_msi_route(kvm_state, msg); + if (ret < 0) { + return ret; + } + irqfd->virq = ret; + } + irqfd->users++; + + ret = kvm_irqchip_add_irqfd(kvm_state, fd, irqfd->virq); + if (ret < 0) { + if (--irqfd->users == 0) { + kvm_irqchip_release_virq(kvm_state, irqfd->virq); + } + return ret; + } + + qemu_set_fd_handler(fd, NULL, NULL, NULL); + + return 0; +} + +static void kvm_virtio_pci_vq_vector_release(VirtIOPCIProxy *proxy, + unsigned int queue_no, + unsigned int vector) +{ + VirtQueue *vq = virtio_get_queue(proxy->vdev, queue_no); + VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector]; + int fd, ret; + + fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vq)); + + ret = kvm_irqchip_remove_irqfd(kvm_state, fd, irqfd->virq); + assert(ret == 0); + + if (--irqfd->users == 0) { + kvm_irqchip_release_virq(kvm_state, irqfd->virq); + } + + qemu_set_fd_handler(fd, virtio_pci_guest_notifier_read, NULL, vq); +} + +static int kvm_virtio_pci_vector_use(PCIDevice *dev, unsigned vector, + MSIMessage msg) +{ + VirtIOPCIProxy *proxy = container_of(dev, VirtIOPCIProxy, pci_dev); + VirtIODevice *vdev = proxy->vdev; + int ret, queue_no; + + for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) { + if (!virtio_queue_get_num(vdev, queue_no)) { + break; + } + if (virtio_queue_vector(vdev, queue_no) != vector) { + continue; + } + ret = kvm_virtio_pci_vq_vector_use(proxy, queue_no, vector, msg); + if (ret < 0) { + goto undo; + } + } + return 0; + +undo: + while (--queue_no >= 0) { + if (virtio_queue_vector(vdev, queue_no) != vector) { + continue; + } + kvm_virtio_pci_vq_vector_release(proxy, queue_no, vector); + } + return ret; +} + +static void kvm_virtio_pci_vector_release(PCIDevice *dev, unsigned vector) +{ + VirtIOPCIProxy *proxy = container_of(dev, VirtIOPCIProxy, pci_dev); + VirtIODevice *vdev = proxy->vdev; + int queue_no; + + for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) { + if (!virtio_queue_get_num(vdev, queue_no)) { + break; + } + if (virtio_queue_vector(vdev, queue_no) != vector) { + continue; + } + kvm_virtio_pci_vq_vector_release(proxy, queue_no, vector); + } +} + static int virtio_pci_set_guest_notifier(void *opaque, int n, bool assign) { VirtIOPCIProxy *proxy = opaque; @@ -555,6 +657,9 @@ static int virtio_pci_set_guest_notifier(void *opaque, int n, bool assign) } else { qemu_set_fd_handler(event_notifier_get_fd(notifier), NULL, NULL, NULL); + /* Test and clear notifier before closing it, + * in case poll callback didn't have time to run. */ + virtio_pci_guest_notifier_read(vq); event_notifier_cleanup(notifier); } @@ -573,6 +678,13 @@ static int virtio_pci_set_guest_notifiers(void *opaque, bool assign) VirtIODevice *vdev = proxy->vdev; int r, n; + /* Must unset vector notifier while guest notifier is still assigned */ + if (kvm_irqchip_in_kernel() && !assign) { + msix_unset_vector_notifiers(&proxy->pci_dev); + g_free(proxy->vector_irqfd); + proxy->vector_irqfd = NULL; + } + for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) { if (!virtio_queue_get_num(vdev, n)) { break; @@ -584,10 +696,24 @@ static int virtio_pci_set_guest_notifiers(void *opaque, bool assign) } } + /* Must set vector notifier after guest notifier has been assigned */ + if (kvm_irqchip_in_kernel() && assign) { + proxy->vector_irqfd = + g_malloc0(sizeof(*proxy->vector_irqfd) * + msix_nr_vectors_allocated(&proxy->pci_dev)); + r = msix_set_vector_notifiers(&proxy->pci_dev, + kvm_virtio_pci_vector_use, + kvm_virtio_pci_vector_release); + if (r < 0) { + goto assign_error; + } + } + return 0; assign_error: /* We get here on assignment failure. Recover by undoing for VQs 0 .. n. */ + assert(assign); while (--n >= 0) { virtio_pci_set_guest_notifier(opaque, n, !assign); } -- cgit v1.2.3