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Violators will be prosecuted; Wed, 18 Jul 2012 16:08:42 +0100 Received: from d06av08.portsmouth.uk.ibm.com (d06av08.portsmouth.uk.ibm.com [9.149.37.249]) by d06nrmr1507.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q6IF8f2W2425012 for ; Wed, 18 Jul 2012 16:08:42 +0100 Received: from d06av08.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av08.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q6IF8d1O020702 for ; Wed, 18 Jul 2012 09:08:40 -0600 Received: from localhost (sig-9-145-185-169.de.ibm.com [9.145.185.169]) by d06av08.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q6IF8dms020694; Wed, 18 Jul 2012 09:08:39 -0600 From: Stefan Hajnoczi To: Cc: , Anthony Liguori , Kevin Wolf , Paolo Bonzini , "Michael S. Tsirkin" , Asias He , Khoa Huynh , Stefan Hajnoczi Subject: [RFC v9 18/27] virtio-blk: Call ioctl() directly instead of irqfd Date: Wed, 18 Jul 2012 16:07:45 +0100 Message-Id: <1342624074-24650-19-git-send-email-stefanha@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1342624074-24650-1-git-send-email-stefanha@linux.vnet.ibm.com> References: <1342624074-24650-1-git-send-email-stefanha@linux.vnet.ibm.com> x-cbid: 12071815-4966-0000-0000-000002FADDEF Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Optimize for the MSI-X enabled and vector unmasked case where it is possible to issue the KVM ioctl() directly instead of using irqfd. This patch introduces a new virtio binding function which tries to notify in a thread-safe way. If this is not possible, the function returns false. Virtio block then knows to use irqfd as a fallback. --- hw/msix.c | 17 +++++++++++++++++ hw/msix.h | 1 + hw/virtio-blk.c | 10 ++++++++-- hw/virtio-pci.c | 8 ++++++++ hw/virtio.c | 9 +++++++++ hw/virtio.h | 3 +++ 6 files changed, 46 insertions(+), 2 deletions(-) diff --git a/hw/msix.c b/hw/msix.c index 7955221..3308604 100644 --- a/hw/msix.c +++ b/hw/msix.c @@ -503,6 +503,23 @@ void msix_notify(PCIDevice *dev, unsigned vector) stl_le_phys(address, data); } +bool msix_try_notify_from_thread(PCIDevice *dev, unsigned vector) +{ + if (unlikely(vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])) { + return false; + } + if (unlikely(msix_is_masked(dev, vector))) { + return false; + } +#ifdef KVM_CAP_IRQCHIP + if (likely(kvm_enabled() && kvm_irqchip_in_kernel())) { + kvm_set_irq(dev->msix_irq_entries[vector].gsi, 1, NULL); + return true; + } +#endif + return false; +} + void msix_reset(PCIDevice *dev) { if (!(dev->cap_present & QEMU_PCI_CAP_MSIX)) diff --git a/hw/msix.h b/hw/msix.h index a8661e1..99fb08f 100644 --- a/hw/msix.h +++ b/hw/msix.h @@ -26,6 +26,7 @@ void msix_vector_unuse(PCIDevice *dev, unsigned vector); void msix_unuse_all_vectors(PCIDevice *dev); void msix_notify(PCIDevice *dev, unsigned vector); +bool msix_try_notify_from_thread(PCIDevice *dev, unsigned vector); void msix_reset(PCIDevice *dev); diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c index bdff68a..efeffa0 100644 --- a/hw/virtio-blk.c +++ b/hw/virtio-blk.c @@ -82,6 +82,12 @@ static void virtio_blk_notify_guest(VirtIOBlock *s) !(s->vdev.guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)))) return; + /* Try to issue the ioctl() directly for speed */ + if (likely(virtio_queue_try_notify_from_thread(s->vq))) { + return; + } + + /* If the fast path didn't work, use irqfd */ event_notifier_set(virtio_queue_get_guest_notifier(s->vq)); } @@ -263,7 +269,7 @@ static void data_plane_start(VirtIOBlock *s) vring_setup(&s->vring, &s->vdev, 0); /* Set up guest notifier (irq) */ - if (s->vdev.binding->set_guest_notifier(s->vdev.binding_opaque, 0, true) != 0) { + if (s->vdev.binding->set_guest_notifiers(s->vdev.binding_opaque, true) != 0) { fprintf(stderr, "virtio-blk failed to set guest notifier, ensure -enable-kvm is set\n"); exit(1); } @@ -315,7 +321,7 @@ static void data_plane_stop(VirtIOBlock *s) event_poll_cleanup(&s->event_poll); /* Clean up guest notifier (irq) */ - s->vdev.binding->set_guest_notifier(s->vdev.binding_opaque, 0, false); + s->vdev.binding->set_guest_notifiers(s->vdev.binding_opaque, false); } static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t val) diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index f1e13af..03512b3 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -106,6 +106,13 @@ static void virtio_pci_notify(void *opaque, uint16_t vector) qemu_set_irq(proxy->pci_dev.irq[0], proxy->vdev->isr & 1); } +static bool virtio_pci_try_notify_from_thread(void *opaque, uint16_t vector) +{ + VirtIOPCIProxy *proxy = opaque; + return msix_enabled(&proxy->pci_dev) && + msix_try_notify_from_thread(&proxy->pci_dev, vector); +} + static void virtio_pci_save_config(void * opaque, QEMUFile *f) { VirtIOPCIProxy *proxy = opaque; @@ -707,6 +714,7 @@ static void virtio_pci_vmstate_change(void *opaque, bool running) static const VirtIOBindings virtio_pci_bindings = { .notify = virtio_pci_notify, + .try_notify_from_thread = virtio_pci_try_notify_from_thread, .save_config = virtio_pci_save_config, .load_config = virtio_pci_load_config, .save_queue = virtio_pci_save_queue, diff --git a/hw/virtio.c b/hw/virtio.c index 064aecf..a1d1a8a 100644 --- a/hw/virtio.c +++ b/hw/virtio.c @@ -689,6 +689,15 @@ static inline int vring_need_event(uint16_t event, uint16_t new, uint16_t old) return (uint16_t)(new - event - 1) < (uint16_t)(new - old); } +bool virtio_queue_try_notify_from_thread(VirtQueue *vq) +{ + VirtIODevice *vdev = vq->vdev; + if (likely(vdev->binding->try_notify_from_thread)) { + return vdev->binding->try_notify_from_thread(vdev->binding_opaque, vq->vector); + } + return false; +} + static bool vring_notify(VirtIODevice *vdev, VirtQueue *vq) { uint16_t old, new; diff --git a/hw/virtio.h b/hw/virtio.h index 400c092..2cdf2be 100644 --- a/hw/virtio.h +++ b/hw/virtio.h @@ -93,6 +93,7 @@ typedef struct VirtQueueElement typedef struct { void (*notify)(void * opaque, uint16_t vector); + bool (*try_notify_from_thread)(void * opaque, uint16_t vector); void (*save_config)(void * opaque, QEMUFile *f); void (*save_queue)(void * opaque, int n, QEMUFile *f); int (*load_config)(void * opaque, QEMUFile *f); @@ -160,6 +161,8 @@ void virtio_cleanup(VirtIODevice *vdev); void virtio_notify_config(VirtIODevice *vdev); +bool virtio_queue_try_notify_from_thread(VirtQueue *vq); + void virtio_queue_set_notification(VirtQueue *vq, int enable); int virtio_queue_ready(VirtQueue *vq);