Message-ID: <f1adce3f-5357-5df4-d6cb-586734921763@intel.com>
Date:   Tue, 15 Feb 2022 17:13:38 +0800
From:   "Zhu, Lingshan" <lingshan.zhu@...el.com>
To:     Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>
Cc:     netdev <netdev@...r.kernel.org>,
        virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH V4 4/4] vDPA/ifcvf: implement shared IRQ feature



On 2/15/2022 11:34 AM, Jason Wang wrote:
> On Mon, Feb 14, 2022 at 10:25 PM Michael S. Tsirkin <mst@...hat.com> 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@...el.com>
>>>> ---
>>>>    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.
OK, we can let the caller check the return value, then re-use 
set_xxx_vector in hw_disable()

Thanks
>>>> +
>>>> +   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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