Date:   Wed, 26 Jan 2022 20:22:34 +0800
From:   "Zhu, Lingshan" <lingshan.zhu@...el.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     jasowang@...hat.com, netdev@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH V2 4/4] vDPA/ifcvf: implement shared IRQ feature



On 1/26/2022 3:42 AM, Michael S. Tsirkin wrote:
> On Tue, Jan 25, 2022 at 05:17:44PM +0800, Zhu Lingshan wrote:
>> 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 | 240 +++++++++++++++++++++++++++-----
>>   3 files changed, 253 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;
>> +	}
>> +
>> +	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;
>> +	}
>> +
>> +	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;
>> +
> This stuffing of errno values into u32 is not a good idea.
will fix this in V3
>
>
>>   	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..d2a2a526f0fc 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
>> +
>>   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;
>>   	/* 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;
>> +	u32 config_irq;
>> +	u32 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 7e2af2d2aaf5..c7070ff01776 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 */
>>   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 */
>>   static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>   {
>>   	struct vring_info *vring = arg;
>> @@ -37,24 +39,77 @@ 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)
>> +{
>> +	struct ifcvf_hw *vf = arg;
>> +	u8 isr;
>> +
>> +	isr = ifc_ioread8(vf->isr);
>> +	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;
> If you use {} in the else branch, use it on the then branch, too.
sure
>
>
>> +}
>>   
>> -	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);
>>   }
>>   
>> @@ -81,58 +136,170 @@ 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, i, ret, irq;
>> -	u16 nvectors, 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;
>> +	irq = pci_irq_vector(pdev, vector);
>> +	ret = devm_request_irq(&pdev->dev, irq,
>> +			       ifcvf_vq_shared_intr_handler, 0,
>> +			       "ifcvf_vq_shared_irq",
>> +			       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;
>> +	irq = pci_irq_vector(pdev, vector);
>> +	ret = devm_request_irq(&pdev->dev, irq,
>> +			       ifcvf_dev_shared_intr_handler, 0,
>> +			       "ifcvf_dev_shared_irq",
>> +			       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;
>>   	}
>> +		ifcvf_set_config_vector(vf, config_vector);
>>   
>> -	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);
>> +	return 0;
>> +}
>>   
>> -			return ret;
>> -		}
>> +static int ifcvf_request_irq(struct ifcvf_adapter *adapter)
> This function was not moved, was it?
>
> Try --minimal or --histogram maybe. Or just
> --anchored=ifcvf_request_irq
Yes, it is not moved, just changed. I tried these parameters,
there are some improvements though seems not significant.
It seems git still finds ifcvf_request_per_vq_irq() uses
some lines of original ifcvf_request_irq().

Thanks for your review and help
Zhu Lingshan
>
>
>> +{
>> +	struct ifcvf_hw *vf = &adapter->vf;
>> +	u16 nvectors, max_intr;
>> +	int ret;
>>   
>> -		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;
>>   }
>>   
>> @@ -436,7 +603,10 @@ 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,
>> -- 
>> 2.27.0

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