x86/PCI: VMD: Separate MSI and MSI-X vector sharing

Child devices in a VMD domain that want to use MSI are slowing down MSI-X
using devices sharing the same vectors.  Move all MSI usage to a single VMD
vector, and MSI-X devices can share the rest.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Jon Derrick <jonathan.derrick@intel.com>

diff --git a/arch/x86/pci/vmd.c b/arch/x86/pci/vmd.c
index 0f77cc1dbb4ee2e25f3afade478692b71879e65b..fd582abfad910cb65d1ad0869c7cc50b38a4c162 100644 (file)
--- a/arch/x86/pci/vmd.c
+++ b/arch/x86/pci/vmd.c
@@ -169,11 +169,14 @@ static irq_hw_number_t vmd_get_hwirq(struct msi_domain_info *info,
  * XXX: We can be even smarter selecting the best IRQ once we solve the
  * affinity problem.
  */
-static struct vmd_irq_list *vmd_next_irq(struct vmd_dev *vmd)
+static struct vmd_irq_list *vmd_next_irq(struct vmd_dev *vmd, struct msi_desc *desc)
 {
-       int i, best = 0;
+       int i, best = 1;
        unsigned long flags;
 
+       if (!desc->msi_attrib.is_msix || vmd->msix_count == 1)
+               return &vmd->irqs[0];
+
        raw_spin_lock_irqsave(&list_lock, flags);
        for (i = 1; i < vmd->msix_count; i++)
                if (vmd->irqs[i].count < vmd->irqs[best].count)
@@ -188,14 +191,15 @@ static int vmd_msi_init(struct irq_domain *domain, struct msi_domain_info *info,
                        unsigned int virq, irq_hw_number_t hwirq,
                        msi_alloc_info_t *arg)
 {
-       struct vmd_dev *vmd = vmd_from_bus(msi_desc_to_pci_dev(arg->desc)->bus);
+       struct msi_desc *desc = arg->desc;
+       struct vmd_dev *vmd = vmd_from_bus(msi_desc_to_pci_dev(desc)->bus);
        struct vmd_irq *vmdirq = kzalloc(sizeof(*vmdirq), GFP_KERNEL);
 
        if (!vmdirq)
                return -ENOMEM;
 
        INIT_LIST_HEAD(&vmdirq->node);
-       vmdirq->irq = vmd_next_irq(vmd);
+       vmdirq->irq = vmd_next_irq(vmd, desc);
        vmdirq->virq = virq;
 
        irq_domain_set_info(domain, virq, vmdirq->irq->vmd_vector, info->chip,