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SubjectRe: [net-next RFC V4 PATCH 3/4] virtio: introduce a method to get the irq of a specific virtqueue
On 06/25/2012 06:14 PM, Michael S. Tsirkin wrote:
> On Mon, Jun 25, 2012 at 05:41:17PM +0800, Jason Wang wrote:
>> Device specific irq optimizations such as irq affinity may be used by virtio
>> drivers. So this patch introduce a new method to get the irq of a specific
>> virtqueue.
>>
>> After this patch, virtio device drivers could query the irq and do device
>> specific optimizations. First user would be virtio-net.
>>
>> Signed-off-by: Jason Wang<jasowang@redhat.com>
>> ---
>> drivers/lguest/lguest_device.c | 8 ++++++++
>> drivers/s390/kvm/kvm_virtio.c | 6 ++++++
>> drivers/virtio/virtio_mmio.c | 8 ++++++++
>> drivers/virtio/virtio_pci.c | 12 ++++++++++++
>> include/linux/virtio_config.h | 4 ++++
>> 5 files changed, 38 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
>> index 9e8388e..bcd080f 100644
>> --- a/drivers/lguest/lguest_device.c
>> +++ b/drivers/lguest/lguest_device.c
>> @@ -392,6 +392,13 @@ static const char *lg_bus_name(struct virtio_device *vdev)
>> return "";
>> }
>>
>> +static int lg_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
>> +{
>> + struct lguest_vq_info *lvq = vq->priv;
>> +
>> + return lvq->config.irq;
>> +}
>> +
>> /* The ops structure which hooks everything together. */
>> static struct virtio_config_ops lguest_config_ops = {
>> .get_features = lg_get_features,
>> @@ -404,6 +411,7 @@ static struct virtio_config_ops lguest_config_ops = {
>> .find_vqs = lg_find_vqs,
>> .del_vqs = lg_del_vqs,
>> .bus_name = lg_bus_name,
>> + .get_vq_irq = lg_get_vq_irq,
>> };
>>
>> /*
>> diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
>> index d74e9ae..a897de2 100644
>> --- a/drivers/s390/kvm/kvm_virtio.c
>> +++ b/drivers/s390/kvm/kvm_virtio.c
>> @@ -268,6 +268,11 @@ static const char *kvm_bus_name(struct virtio_device *vdev)
>> return "";
>> }
>>
>> +static int kvm_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
>> +{
>> + return 0x2603;
>> +}
>> +
>> /*
>> * The config ops structure as defined by virtio config
>> */
>> @@ -282,6 +287,7 @@ static struct virtio_config_ops kvm_vq_configspace_ops = {
>> .find_vqs = kvm_find_vqs,
>> .del_vqs = kvm_del_vqs,
>> .bus_name = kvm_bus_name,
>> + .get_vq_irq = kvm_get_vq_irq,
>> };
>>
>> /*
>> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
>> index f5432b6..2ba37ed 100644
>> --- a/drivers/virtio/virtio_mmio.c
>> +++ b/drivers/virtio/virtio_mmio.c
>> @@ -411,6 +411,13 @@ static const char *vm_bus_name(struct virtio_device *vdev)
>> return vm_dev->pdev->name;
>> }
>>
>> +static int vm_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
>> +{
>> + struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
>> +
>> + return platform_get_irq(vm_dev->pdev, 0);
>> +}
>> +
>> static struct virtio_config_ops virtio_mmio_config_ops = {
>> .get = vm_get,
>> .set = vm_set,
>> @@ -422,6 +429,7 @@ static struct virtio_config_ops virtio_mmio_config_ops = {
>> .get_features = vm_get_features,
>> .finalize_features = vm_finalize_features,
>> .bus_name = vm_bus_name,
>> + .get_vq_irq = vm_get_vq_irq,
>> };
>>
>>
>> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
>> index adb24f2..c062227 100644
>> --- a/drivers/virtio/virtio_pci.c
>> +++ b/drivers/virtio/virtio_pci.c
>> @@ -607,6 +607,17 @@ static const char *vp_bus_name(struct virtio_device *vdev)
>> return pci_name(vp_dev->pci_dev);
>> }
>>
>> +static int vp_get_vq_irq(struct virtio_device *vdev, struct virtqueue *vq)
>> +{
>> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
>> + struct virtio_pci_vq_info *info = vq->priv;
>> +
>> + if (vp_dev->intx_enabled)
>> + return vp_dev->pci_dev->irq;
>> + else
>> + return vp_dev->msix_entries[info->msix_vector].vector;
>> +}
>> +
>> static struct virtio_config_ops virtio_pci_config_ops = {
>> .get = vp_get,
>> .set = vp_set,
>> @@ -618,6 +629,7 @@ static struct virtio_config_ops virtio_pci_config_ops = {
>> .get_features = vp_get_features,
>> .finalize_features = vp_finalize_features,
>> .bus_name = vp_bus_name,
>> + .get_vq_irq = vp_get_vq_irq,
>> };
>>
>> static void virtio_pci_release_dev(struct device *_d)
>> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
>> index fc457f4..acd6930 100644
>> --- a/include/linux/virtio_config.h
>> +++ b/include/linux/virtio_config.h
>> @@ -98,6 +98,9 @@
>> * vdev: the virtio_device
>> * This returns a pointer to the bus name a la pci_name from which
>> * the caller can then copy.
>> + * @get_vq_irq: get the irq numer of the specific virt queue.
>> + * vdev: the virtio_device
>> + * vq: the virtqueue
> What if the vq does not have an IRQ? E.g. control vqs don't.
> What if the IRQ is shared between VQs? Between devices?
> The need to cleanup affinity on destroy is also nasty.
> How about we expose a set_affinity API instead?

Or exposed the irq information such as sharing, level/edge. But I think
exposing the set_affinity API is enough for multiqueue virtio-net.
> Then:
> - non PCI can ignore for now
> - with a per vq vector we can force it
> - with a shared MSI we make it an OR over all affinities
> - with a level interrupt we can ignore it
> - on cleanup we can do it in core

Looks good, thanks.
>
>> */
>> typedef void vq_callback_t(struct virtqueue *);
>> struct virtio_config_ops {
>> @@ -116,6 +119,7 @@ struct virtio_config_ops {
>> u32 (*get_features)(struct virtio_device *vdev);
>> void (*finalize_features)(struct virtio_device *vdev);
>> const char *(*bus_name)(struct virtio_device *vdev);
>> + int (*get_vq_irq)(struct virtio_device *vdev, struct virtqueue *vq);
>> };
>>
>> /* If driver didn't advertise the feature, it will never appear. */
>> --
>> 1.7.1



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