[PATCH] vp_vdpa: fix the method of calculating vectors

[gavin.liu]

From: Yuxue Liu <yuxue....@jaguarmicro.com>

When there is a ctlq and it doesn't require interrupt
callbacks,the original method of calculating vectors
wastes hardware MSI or MSI-X resources as well as system
IRQ resources. Referencing the per_vq_vectors mode in the
vp_find_vqs_msix function, calculate the required number
of vectors based on whether the callback is set.

Signed-off-by: Yuxue Liu <yuxue....@jaguarmicro.com>
---
 drivers/vdpa/virtio_pci/vp_vdpa.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c 
b/drivers/vdpa/virtio_pci/vp_vdpa.c
index 281287fae89f..5066970b2570 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
@@ -160,7 +160,13 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa)
        struct pci_dev *pdev = mdev->pci_dev;
        int i, ret, irq;
        int queues = vp_vdpa->queues;
-       int vectors = queues + 1;
+       int vectors = 0;
+
+       for (i = 0; i < queues; i++) {
+               if (vp_vdpa->vring[i].cb.callback != NULL)
+                       vectors++;
+       }
+       vectors = vectors + 1;
 
        ret = pci_alloc_irq_vectors(pdev, vectors, vectors, PCI_IRQ_MSIX);
        if (ret != vectors) {
@@ -172,7 +178,7 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa)
 
        vp_vdpa->vectors = vectors;
 
-       for (i = 0; i < queues; i++) {
+       for (i = 0; i < vectors - 1; i++) {
                snprintf(vp_vdpa->vring[i].msix_name, VP_VDPA_NAME_SIZE,
                        "vp-vdpa[%s]-%d\n", pci_name(pdev), i);
                irq = pci_irq_vector(pdev, i);
@@ -191,7 +197,7 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa)
 
        snprintf(vp_vdpa->msix_name, VP_VDPA_NAME_SIZE, "vp-vdpa[%s]-config\n",
                 pci_name(pdev));
-       irq = pci_irq_vector(pdev, queues);
+       irq = pci_irq_vector(pdev, vectors - 1);
        ret = devm_request_irq(&pdev->dev, irq, vp_vdpa_config_handler, 0,
                               vp_vdpa->msix_name, vp_vdpa);
        if (ret) {
@@ -199,7 +205,7 @@ static int vp_vdpa_request_irq(struct vp_vdpa *vp_vdpa)
                        "vp_vdpa: fail to request irq for vq %d\n", i);
                        goto err;
        }
-       vp_modern_config_vector(mdev, queues);
+       vp_modern_config_vector(mdev, vectors - 1);
        vp_vdpa->config_irq = irq;
 
        return 0;
-- 
2.43.0