Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature

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On Mon, Feb 14, 2022 at 10:25 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
>
> On Mon, Feb 14, 2022 at 03:19:25PM +0800, Jason Wang wrote:
> >
> > 在 2022/2/3 下午3:27, Zhu Lingshan 写道:
> > > On some platforms/devices, there may not be enough MSI vector
> > > slots allocated for virtqueues and config changes. In such a case,
> > > the interrupt sources(virtqueues, config changes) must share
> > > an IRQ/vector, to avoid initialization failures, keep
> > > the device functional.
> > >
> > > This commit handles three cases:
> > > (1) number of the allocated vectors == the number of virtqueues + 1
> > > (config changes), every virtqueue and the config interrupt has
> > > a separated vector/IRQ, the best and the most likely case.
> > > (2) number of the allocated vectors is less than the best case, but
> > > greater than 1. In this case, all virtqueues share a vector/IRQ,
> > > the config interrupt has a separated vector/IRQ
> > > (3) only one vector is allocated, in this case, the virtqueues and
> > > the config interrupt share a vector/IRQ. The worst and most
> > > unlikely case.
> > >
> > > Otherwise, it needs to fail.
> > >
> > > This commit introduces some helper functions:
> > > ifcvf_set_vq_vector() and ifcvf_set_config_vector() sets virtqueue
> > > vector and config vector in the device config space, so that
> > > the device can send interrupt DMA.
> > >
> > > This commit adds some fields in struct ifcvf_hw and re-placed
> > > the existed fields to be aligned with the cacheline.
> > >
> > > Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> > > ---
> > >   drivers/vdpa/ifcvf/ifcvf_base.c |  47 ++++--
> > >   drivers/vdpa/ifcvf/ifcvf_base.h |  23 ++-
> > >   drivers/vdpa/ifcvf/ifcvf_main.c | 243 +++++++++++++++++++++++++++-----
> > >   3 files changed, 256 insertions(+), 57 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > index 397692ae671c..18dcb63ab1e3 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> > > @@ -15,6 +15,36 @@ struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw)
> > >     return container_of(hw, struct ifcvf_adapter, vf);
> > >   }
> > > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector)
> > > +{
> > > +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > +
> > > +   ifc_iowrite16(qid, &cfg->queue_select);
> > > +   ifc_iowrite16(vector, &cfg->queue_msix_vector);
> > > +   if (ifc_ioread16(&cfg->queue_msix_vector) == VIRTIO_MSI_NO_VECTOR) {
> > > +           IFCVF_ERR(ifcvf->pdev, "No msix vector for queue %u\n", qid);
> > > +                   return -EINVAL;
> > > +   }
> >
> >
> > Let's leave this check for the caller, E.g can caller try to assign
> > NO_VECTOR during uni-nit?
>
>
> Hmm I'm not sure I agree. Caller will have to write queue select
> again, and that's an extra IO, which is a waste.
> And having function checking itself just seems better contained.

It's as simple as just return what we read here like virtio_pci did:

u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
                           u16 index, u16 vector)
{
        struct virtio_pci_common_cfg __iomem *cfg = mdev->common;

        vp_iowrite16(index, &cfg->queue_select);
        vp_iowrite16(vector, &cfg->queue_msix_vector);
        /* Flush the write out to device */
        return vp_ioread16(&cfg->queue_msix_vector);
}
EXPORT_SYMBOL_GPL(vp_modern_queue_vector);

Then the caller can decide to check it with NO_VECTOR if needed.
Current code will break the callers that want to set NO_VECTOR.

>
> >
> > > +
> > > +   return 0;
> > > +}
> > > +
> > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector)
> > > +{
> > > +   struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> > > +   struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
> > > +
> > > +   cfg = hw->common_cfg;
> > > +   ifc_iowrite16(vector,  &cfg->msix_config);
> > > +   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > +           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > +           return -EINVAL;
> > > +   }
> >
> >
> > Similar question as above.
> >
> >
> > > +
> > > +   return 0;
> > > +}
> > > +
> > >   static void __iomem *get_cap_addr(struct ifcvf_hw *hw,
> > >                               struct virtio_pci_cap *cap)
> > >   {
> > > @@ -140,6 +170,8 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
> > >               hw->common_cfg, hw->notify_base, hw->isr,
> > >               hw->dev_cfg, hw->notify_off_multiplier);
> > > +   hw->vqs_shared_irq = -EINVAL;
> > > +
> > >     return 0;
> > >   }
> > > @@ -321,12 +353,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > >     ifcvf = vf_to_adapter(hw);
> > >     cfg = hw->common_cfg;
> > > -   ifc_iowrite16(IFCVF_MSI_CONFIG_OFF, &cfg->msix_config);
> > > -
> > > -   if (ifc_ioread16(&cfg->msix_config) == VIRTIO_MSI_NO_VECTOR) {
> > > -           IFCVF_ERR(ifcvf->pdev, "No msix vector for device config\n");
> > > -           return -EINVAL;
> > > -   }
> > >     for (i = 0; i < hw->nr_vring; i++) {
> > >             if (!hw->vring[i].ready)
> > > @@ -340,15 +366,6 @@ static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> > >             ifc_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> > >                                  &cfg->queue_used_hi);
> > >             ifc_iowrite16(hw->vring[i].size, &cfg->queue_size);
> > > -           ifc_iowrite16(i + IFCVF_MSI_QUEUE_OFF, &cfg->queue_msix_vector);
> > > -
> > > -           if (ifc_ioread16(&cfg->queue_msix_vector) ==
> > > -               VIRTIO_MSI_NO_VECTOR) {
> > > -                   IFCVF_ERR(ifcvf->pdev,
> > > -                             "No msix vector for queue %u\n", i);
> > > -                   return -EINVAL;
> > > -           }
> > > -
> > >             ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> > >             ifc_iowrite16(1, &cfg->queue_enable);
> > >     }
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > index 949b4fb9d554..9cfe088c82e9 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> > > @@ -27,8 +27,6 @@
> > >   #define IFCVF_QUEUE_ALIGNMENT     PAGE_SIZE
> > >   #define IFCVF_QUEUE_MAX           32768
> > > -#define IFCVF_MSI_CONFIG_OFF       0
> > > -#define IFCVF_MSI_QUEUE_OFF        1
> > >   #define IFCVF_PCI_MAX_RESOURCE    6
> > >   #define IFCVF_LM_CFG_SIZE         0x40
> > > @@ -42,6 +40,13 @@
> > >   #define ifcvf_private_to_vf(adapter) \
> > >     (&((struct ifcvf_adapter *)adapter)->vf)
> > > +/* all vqs and config interrupt has its own vector */
> > > +#define MSIX_VECTOR_PER_VQ_AND_CONFIG              1
> > > +/* all vqs share a vector, and config interrupt has a separate vector */
> > > +#define MSIX_VECTOR_SHARED_VQ_AND_CONFIG   2
> > > +/* all vqs and config interrupt share a vector */
> > > +#define MSIX_VECTOR_DEV_SHARED                     3
> >
> >
> > I think there's no much value to differ 2 from 3 consider config interrupt
> > should be rare.
>
>
> Yes but if we do not have a dedicated vector then we need an
> extra device IO (in fact, a read) on each interrupt.

Ok, right.

>
> >
> > > +
> > >   static inline u8 ifc_ioread8(u8 __iomem *addr)
> > >   {
> > >     return ioread8(addr);
> > > @@ -97,25 +102,27 @@ struct ifcvf_hw {
> > >     u8 __iomem *isr;
> > >     /* Live migration */
> > >     u8 __iomem *lm_cfg;
> > > -   u16 nr_vring;
> >
> >
> > Any reason for moving nv_vring, config_size, and other stuffs?
> >
> >
> > >     /* Notification bar number */
> > >     u8 notify_bar;
> > > +   u8 msix_vector_status;
> > > +   /* virtio-net or virtio-blk device config size */
> > > +   u32 config_size;
> > >     /* Notificaiton bar address */
> > >     void __iomem *notify_base;
> > >     phys_addr_t notify_base_pa;
> > >     u32 notify_off_multiplier;
> > > +   u32 dev_type;
> > >     u64 req_features;
> > >     u64 hw_features;
> > > -   u32 dev_type;
> > >     struct virtio_pci_common_cfg __iomem *common_cfg;
> > >     void __iomem *dev_cfg;
> > >     struct vring_info vring[IFCVF_MAX_QUEUES];
> > >     void __iomem * const *base;
> > >     char config_msix_name[256];
> > >     struct vdpa_callback config_cb;
> > > -   unsigned int config_irq;
> > > -   /* virtio-net or virtio-blk device config size */
> > > -   u32 config_size;
> > > +   int config_irq;
> > > +   int vqs_shared_irq;
> > > +   u16 nr_vring;
> > >   };
> > >   struct ifcvf_adapter {
> > > @@ -160,4 +167,6 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
> > >   struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> > >   int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> > >   u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> > > +int ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> > > +int ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> > >   #endif /* _IFCVF_H_ */
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > index 44c89ab0b6da..ca414399f040 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > @@ -17,6 +17,7 @@
> > >   #define DRIVER_AUTHOR   "Intel Corporation"
> > >   #define IFCVF_DRIVER_NAME       "ifcvf"
> > > +/* handles config interrupt */
> >
> >
> > This seems unrelated to the shared IRQ logic and it looks useless since it's
> > easily to deduce it from the function name below.
> >
> >
> > >   static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> > >   {
> > >     struct ifcvf_hw *vf = arg;
> > > @@ -27,6 +28,7 @@ static irqreturn_t ifcvf_config_changed(int irq, void *arg)
> > >     return IRQ_HANDLED;
> > >   }
> > > +/* handles vqs interrupt */
> >
> >
> > So did this.
> >
> >
> > >   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> > >   {
> > >     struct vring_info *vring = arg;
> > > @@ -37,24 +39,78 @@ static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
> > >     return IRQ_HANDLED;
> > >   }
> > > +/* handls vqs shared interrupt */
> > > +static irqreturn_t ifcvf_vq_shared_intr_handler(int irq, void *arg)
> > > +{
> > > +   struct ifcvf_hw *vf = arg;
> > > +   struct vring_info *vring;
> > > +   int i;
> > > +
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           vring = &vf->vring[i];
> > > +           if (vring->cb.callback)
> > > +                   vf->vring->cb.callback(vring->cb.private);
> > > +   }
> > > +
> > > +   return IRQ_HANDLED;
> > > +}
> > > +
> > > +/* handles a shared interrupt for vqs and config */
> > > +static irqreturn_t ifcvf_dev_shared_intr_handler(int irq, void *arg)
>
> shared is not a good name given IRQ_SHARED is not set.
> maybe "common"? "reused"?
>
> > > +{
> > > +   struct ifcvf_hw *vf = arg;
> > > +   u8 isr;
> > > +
> > > +   isr = ifc_ioread8(vf->isr);
> >
> >
> > We need to exactly what vp_interrupt do here. Checking against vf->isr first
> > and return IRQ_NONE if it is not set.
>
> no, vf->isr is not set for VQ interrupts.

I actually wonder what's the actual behaviour of IFCVF.

> If need to actually poke
> at the VQ to know.
>
> > Always return IRQ_HANDLED will break the device who shares an irq with
> > IFCVF.
>
>
> It's a MSI, not INT#. So interrupt is not shared as such - it's only
> sharing vector between config and vq.

Right, I thought it was a shared one as virito_pci did.

>
>
> >
> > > +   if (isr & VIRTIO_PCI_ISR_CONFIG)
> > > +           ifcvf_config_changed(irq, arg);
> > > +
> > > +   return ifcvf_vq_shared_intr_handler(irq, arg);
> > > +}
> > > +
> > >   static void ifcvf_free_irq_vectors(void *data)
> > >   {
> > >     pci_free_irq_vectors(data);
> > >   }
> > > -static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > +static void ifcvf_free_vq_irq(struct ifcvf_adapter *adapter, int queues)
> > >   {
> > >     struct pci_dev *pdev = adapter->pdev;
> > >     struct ifcvf_hw *vf = &adapter->vf;
> > >     int i;
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG) {
> > > +           for (i = 0; i < queues; i++) {
> > > +                   devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > +                   vf->vring[i].irq = -EINVAL;
> > > +           }
> > > +   } else {
> > > +           devm_free_irq(&pdev->dev, vf->vqs_shared_irq, vf);
> > > +           vf->vqs_shared_irq = -EINVAL;
> > > +   }
> > > +}
> > > -   for (i = 0; i < queues; i++) {
> > > -           devm_free_irq(&pdev->dev, vf->vring[i].irq, &vf->vring[i]);
> > > -           vf->vring[i].irq = -EINVAL;
> > > +static void ifcvf_free_config_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +
> > > +   /* If the irq is shared by all vqs and the config interrupt,
> > > +    * it is already freed in ifcvf_free_vq_irq, so here only
> > > +    * need to free config irq when msix_vector_status != MSIX_VECTOR_DEV_SHARED
> > > +    */
> > > +   if (vf->msix_vector_status != MSIX_VECTOR_DEV_SHARED) {
> > > +           devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > +           vf->config_irq = -EINVAL;
> > >     }
> > > +}
> > > +
> > > +static void ifcvf_free_irq(struct ifcvf_adapter *adapter, int queues)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > -   devm_free_irq(&pdev->dev, vf->config_irq, vf);
> > > +   ifcvf_free_vq_irq(adapter, queues);
> > > +   ifcvf_free_config_irq(adapter);
> > >     ifcvf_free_irq_vectors(pdev);
> > >   }
> > > @@ -86,58 +142,172 @@ static int ifcvf_alloc_vectors(struct ifcvf_adapter *adapter)
> > >     return ret;
> > >   }
> > > -static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > +static int ifcvf_request_per_vq_irq(struct ifcvf_adapter *adapter)
> > >   {
> > >     struct pci_dev *pdev = adapter->pdev;
> > >     struct ifcvf_hw *vf = &adapter->vf;
> > > -   int vector, nvectors, i, ret, irq;
> > > -   u16 max_intr;
> > > +   int i, vector, ret, irq;
> > > -   nvectors = ifcvf_alloc_vectors(adapter);
> > > -   if (!(nvectors > 0))
> > > -           return nvectors;
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n", pci_name(pdev), i);
> > > +           vector = i;
> > > +           irq = pci_irq_vector(pdev, vector);
> > > +           ret = devm_request_irq(&pdev->dev, irq,
> > > +                                  ifcvf_intr_handler, 0,
> > > +                                  vf->vring[i].msix_name,
> > > +                                  &vf->vring[i]);
> > > +           if (ret) {
> > > +                   IFCVF_ERR(pdev, "Failed to request irq for vq %d\n", i);
> > > +                   ifcvf_free_vq_irq(adapter, i);
> > > +           } else {
> > > +                   vf->vring[i].irq = irq;
> > > +                   ifcvf_set_vq_vector(vf, i, vector);
> > > +           }
> > > +   }
> > > -   max_intr = vf->nr_vring + 1;
> > > +   vf->vqs_shared_irq = -EINVAL;
> > > +
> > > +   return 0;
> > > +}
> > > +
> > > +static int ifcvf_request_shared_vq_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int i, vector, ret, irq;
> > > +
> > > +   vector = 0;
> > > +   /* reuse msix_name[256] space of vring0 to store shared vqs interrupt name */
> >
> >
> > I think we can remove this comment since the code is straightforward.
> >
> >
> > > +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-vqs-shared-irq\n", pci_name(pdev));
> > > +   irq = pci_irq_vector(pdev, vector);
> > > +   ret = devm_request_irq(&pdev->dev, irq,
> > > +                          ifcvf_vq_shared_intr_handler, 0,
> > > +                          vf->vring[0].msix_name, vf);
> > > +   if (ret) {
> > > +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > > +
> > > +           return ret;
> > > +   }
> > > +
> > > +   vf->vqs_shared_irq = irq;
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           vf->vring[i].irq = -EINVAL;
> > > +           ifcvf_set_vq_vector(vf, i, vector);
> > > +   }
> > > +
> > > +   return 0;
> > > +
> > > +}
> > > +
> > > +static int ifcvf_request_dev_shared_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int i, vector, ret, irq;
> > > +
> > > +   vector = 0;
> > > +   /* reuse msix_name[256] space of vring0 to store shared device interrupt name */
> > > +   snprintf(vf->vring[0].msix_name, 256, "ifcvf[%s]-dev-shared-irq\n", pci_name(pdev));
> > > +   irq = pci_irq_vector(pdev, vector);
> > > +   ret = devm_request_irq(&pdev->dev, irq,
> > > +                          ifcvf_dev_shared_intr_handler, 0,
> > > +                          vf->vring[0].msix_name, vf);
> > > +   if (ret) {
> > > +           IFCVF_ERR(pdev, "Failed to request shared irq for vf\n");
> > > -   ret = pci_alloc_irq_vectors(pdev, max_intr,
> > > -                               max_intr, PCI_IRQ_MSIX);
> > > -   if (ret < 0) {
> > > -           IFCVF_ERR(pdev, "Failed to alloc IRQ vectors\n");
> > >             return ret;
> > >     }
> > > +   vf->vqs_shared_irq = irq;
> > > +   for (i = 0; i < vf->nr_vring; i++) {
> > > +           vf->vring[i].irq = -EINVAL;
> > > +           ifcvf_set_vq_vector(vf, i, vector);
> > > +   }
> > > +
> > > +   vf->config_irq = irq;
> > > +   ifcvf_set_config_vector(vf, vector);
> > > +
> > > +   return 0;
> > > +
> > > +}
> > > +
> > > +static int ifcvf_request_vq_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int ret;
> > > +
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > +           ret = ifcvf_request_per_vq_irq(adapter);
> > > +   else
> > > +           ret = ifcvf_request_shared_vq_irq(adapter);
> > > +
> > > +   return ret;
> > > +}
> > > +
> > > +static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
> > > +{
> > > +   struct pci_dev *pdev = adapter->pdev;
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int config_vector, ret;
> > > +
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> > > +           return 0;
> > > +
> > > +   if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> > > +           /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
> > > +           config_vector = vf->nr_vring;
> > > +
> > > +   if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> > > +           /* vector 0 for vqs and 1 for config interrupt */
> > > +           config_vector = 1;
> > > +
> > >     snprintf(vf->config_msix_name, 256, "ifcvf[%s]-config\n",
> > >              pci_name(pdev));
> > > -   vector = 0;
> > > -   vf->config_irq = pci_irq_vector(pdev, vector);
> > > +   vf->config_irq = pci_irq_vector(pdev, config_vector);
> > >     ret = devm_request_irq(&pdev->dev, vf->config_irq,
> > >                            ifcvf_config_changed, 0,
> > >                            vf->config_msix_name, vf);
> > >     if (ret) {
> > >             IFCVF_ERR(pdev, "Failed to request config irq\n");
> > > +           ifcvf_free_vq_irq(adapter, vf->nr_vring);
> > >             return ret;
> > >     }
> > > -   for (i = 0; i < vf->nr_vring; i++) {
> > > -           snprintf(vf->vring[i].msix_name, 256, "ifcvf[%s]-%d\n",
> > > -                    pci_name(pdev), i);
> > > -           vector = i + IFCVF_MSI_QUEUE_OFF;
> > > -           irq = pci_irq_vector(pdev, vector);
> > > -           ret = devm_request_irq(&pdev->dev, irq,
> > > -                                  ifcvf_intr_handler, 0,
> > > -                                  vf->vring[i].msix_name,
> > > -                                  &vf->vring[i]);
> > > -           if (ret) {
> > > -                   IFCVF_ERR(pdev,
> > > -                             "Failed to request irq for vq %d\n", i);
> > > -                   ifcvf_free_irq(adapter, i);
> > > +   ifcvf_set_config_vector(vf, config_vector);
> > > -                   return ret;
> > > -           }
> > > +   return 0;
> > > +}
> > > +
> > > +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> > > +{
> >
> >
> > As replied above, I think having two modes should be sufficient and the code
> > could be greatly simplified.
> >
> > Thanks
> >
>
> Well it is claimed there are platforms where we are short
> on vectors. 3 versus 2 seems a 50% saving. You disagree?

I think we can 2 vectors (a dedicated for config).

Thanks

>
> > > +   struct ifcvf_hw *vf = &adapter->vf;
> > > +   int nvectors, ret, max_intr;
> > > -           vf->vring[i].irq = irq;
> > > +   nvectors = ifcvf_alloc_vectors(adapter);
> > > +   if (!(nvectors > 0))
> > > +           return nvectors;
> > > +
> > > +   vf->msix_vector_status = MSIX_VECTOR_PER_VQ_AND_CONFIG;
> > > +   max_intr = vf->nr_vring + 1;
> > > +   if (nvectors < max_intr)
> > > +           vf->msix_vector_status = MSIX_VECTOR_SHARED_VQ_AND_CONFIG;
> > > +
> > > +   if (nvectors == 1) {
> > > +           vf->msix_vector_status = MSIX_VECTOR_DEV_SHARED;
> > > +           ret = ifcvf_request_dev_shared_irq(adapter);
> > > +
> > > +           return ret;
> > >     }
> > > +   ret = ifcvf_request_vq_irq(adapter);
> > > +   if (ret)
> > > +           return ret;
> > > +
> > > +   ret = ifcvf_request_config_irq(adapter);
> > > +
> > > +   if (ret)
> > > +           return ret;
> > > +
> > >     return 0;
> > >   }
> > > @@ -441,7 +611,10 @@ static int ifcvf_vdpa_get_vq_irq(struct vdpa_device *vdpa_dev,
> > >   {
> > >     struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> > > -   return vf->vring[qid].irq;
> > > +   if (vf->vqs_shared_irq < 0)
> > > +           return vf->vring[qid].irq;
> > > +   else
> > > +           return -EINVAL;
> > >   }
> > >   static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
>

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