Patchwork [RFC,2/9] virtio-pci: support host notifiers in TCG mode

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Submitter Nicholas A. Bellinger
Date July 24, 2012, 10:33 p.m.
Message ID <1343169246-17636-3-git-send-email-nab@linux-iscsi.org>
Download mbox | patch
Permalink /patch/173070/
State New
Headers show

Comments

Nicholas A. Bellinger - July 24, 2012, 10:33 p.m.
From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Normally host notifiers are only used together with vhost-net in KVM
mode.  It is occassionally useful to use vhost with TCG mode, mainly for
testing and development.  This isn't hard to achieve, simply fall back
to notifying the host notifier manually from qemu if KVM mode is
disabled.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 hw/virtio-pci.c |   23 ++++++++++++++++++++---
 hw/virtio.c     |    7 +++++++
 2 files changed, 27 insertions(+), 3 deletions(-)
Paolo Bonzini - July 25, 2012, 6:50 a.m.
Il 25/07/2012 00:33, Nicholas A. Bellinger ha scritto:
> From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> 
> Normally host notifiers are only used together with vhost-net in KVM
> mode.  It is occassionally useful to use vhost with TCG mode, mainly for
> testing and development.  This isn't hard to achieve, simply fall back
> to notifying the host notifier manually from qemu if KVM mode is
> disabled.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> Cc: Anthony Liguori <aliguori@us.ibm.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>  hw/virtio-pci.c |   23 ++++++++++++++++++++---
>  hw/virtio.c     |    7 +++++++
>  2 files changed, 27 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> index 4e03f0b..538eef4 100644
> --- a/hw/virtio-pci.c
> +++ b/hw/virtio-pci.c
> @@ -249,6 +249,25 @@ void virtio_pci_reset(DeviceState *d)
>      proxy->flags &= ~VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
>  }
>  
> +static void virtio_pci_queue_notify(VirtIOPCIProxy *proxy, uint32_t n)
> +{
> +    VirtQueue *vq;
> +    EventNotifier *notifier;
> +
> +    if (n >= VIRTIO_PCI_QUEUE_MAX) {
> +        return;
> +    }
> +
> +    vq = virtio_get_queue(proxy->vdev, n);
> +    notifier = virtio_queue_get_host_notifier(vq);
> +    if (event_notifier_valid(notifier)) {
> +        printf("notifying vq %u host notifier from userspace\n", n);

Debug printf.

> +        event_notifier_notify(notifier);
> +    } else {
> +        virtio_queue_notify_vq(vq);
> +    }

This can be done directly in virtio_queue_notify, there is nothing
specific to virtio-pci.

> +}
> +
>  static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
>  {
>      VirtIOPCIProxy *proxy = opaque;
> @@ -278,9 +297,7 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
>              vdev->queue_sel = val;
>          break;
>      case VIRTIO_PCI_QUEUE_NOTIFY:
> -        if (val < VIRTIO_PCI_QUEUE_MAX) {
> -            virtio_queue_notify(vdev, val);
> -        }
> +        virtio_pci_queue_notify(proxy, val);
>          break;
>      case VIRTIO_PCI_STATUS:
>          if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
> diff --git a/hw/virtio.c b/hw/virtio.c
> index d146f86..36a18b5 100644
> --- a/hw/virtio.c
> +++ b/hw/virtio.c
> @@ -536,6 +536,11 @@ void virtio_reset(void *opaque)
>          vdev->vq[i].signalled_used = 0;
>          vdev->vq[i].signalled_used_valid = false;
>          vdev->vq[i].notification = true;
> +
> +        assert(!event_notifier_valid(&vdev->vq[i].guest_notifier));
> +        assert(!event_notifier_valid(&vdev->vq[i].host_notifier));
> +        vdev->vq[i].guest_notifier = EVENT_NOTIFIER_INITIALIZER;
> +        vdev->vq[i].host_notifier = EVENT_NOTIFIER_INITIALIZER;

Given the assertions, the assignments should be no-ops.

>      }
>  }
>  
> @@ -905,6 +910,8 @@ VirtIODevice *virtio_common_init(const char *name, uint16_t device_id,
>      for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
>          vdev->vq[i].vector = VIRTIO_NO_VECTOR;
>          vdev->vq[i].vdev = vdev;
> +        vdev->vq[i].guest_notifier = EVENT_NOTIFIER_INITIALIZER;
> +        vdev->vq[i].host_notifier = EVENT_NOTIFIER_INITIALIZER;
>      }
>  
>      vdev->name = name;
>

Patch

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 4e03f0b..538eef4 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -249,6 +249,25 @@  void virtio_pci_reset(DeviceState *d)
     proxy->flags &= ~VIRTIO_PCI_FLAG_BUS_MASTER_BUG;
 }
 
+static void virtio_pci_queue_notify(VirtIOPCIProxy *proxy, uint32_t n)
+{
+    VirtQueue *vq;
+    EventNotifier *notifier;
+
+    if (n >= VIRTIO_PCI_QUEUE_MAX) {
+        return;
+    }
+
+    vq = virtio_get_queue(proxy->vdev, n);
+    notifier = virtio_queue_get_host_notifier(vq);
+    if (event_notifier_valid(notifier)) {
+        printf("notifying vq %u host notifier from userspace\n", n);
+        event_notifier_notify(notifier);
+    } else {
+        virtio_queue_notify_vq(vq);
+    }
+}
+
 static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 {
     VirtIOPCIProxy *proxy = opaque;
@@ -278,9 +297,7 @@  static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
             vdev->queue_sel = val;
         break;
     case VIRTIO_PCI_QUEUE_NOTIFY:
-        if (val < VIRTIO_PCI_QUEUE_MAX) {
-            virtio_queue_notify(vdev, val);
-        }
+        virtio_pci_queue_notify(proxy, val);
         break;
     case VIRTIO_PCI_STATUS:
         if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
diff --git a/hw/virtio.c b/hw/virtio.c
index d146f86..36a18b5 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -536,6 +536,11 @@  void virtio_reset(void *opaque)
         vdev->vq[i].signalled_used = 0;
         vdev->vq[i].signalled_used_valid = false;
         vdev->vq[i].notification = true;
+
+        assert(!event_notifier_valid(&vdev->vq[i].guest_notifier));
+        assert(!event_notifier_valid(&vdev->vq[i].host_notifier));
+        vdev->vq[i].guest_notifier = EVENT_NOTIFIER_INITIALIZER;
+        vdev->vq[i].host_notifier = EVENT_NOTIFIER_INITIALIZER;
     }
 }
 
@@ -905,6 +910,8 @@  VirtIODevice *virtio_common_init(const char *name, uint16_t device_id,
     for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
         vdev->vq[i].vector = VIRTIO_NO_VECTOR;
         vdev->vq[i].vdev = vdev;
+        vdev->vq[i].guest_notifier = EVENT_NOTIFIER_INITIALIZER;
+        vdev->vq[i].host_notifier = EVENT_NOTIFIER_INITIALIZER;
     }
 
     vdev->name = name;