PCI: vmd: Offset Client VMD MSI-X vectors

Client VMD platforms have a software-triggered MSI-X vector 0 that will
not forward hardware-remapped MSI from the sub-device domain. This
causes an issue with VMD platforms that use AHCI behind VMD and have a
single MSI-X vector remapped to VMD vector 0. Add a VMD MSI-X vector
offset for these platforms.

Link: https://lore.kernel.org/r/20201102222223.92978-1-jonathan.derrick@intel.com
Tested-by: Jian-Hong Pan <jhp@endlessos.org>
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index f375c21..c31e4d5 100644 (file)
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -53,6 +53,12 @@ enum vmd_features {
         * vendor-specific capability space
         */
        VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP        = (1 << 2),
+
+       /*
+        * Device may use MSI-X vector 0 for software triggering and will not
+        * be used for MSI remapping
+        */
+       VMD_FEAT_OFFSET_FIRST_VECTOR            = (1 << 3),
 };
 
 /*
@@ -104,6 +110,7 @@ struct vmd_dev {
        struct irq_domain       *irq_domain;
        struct pci_bus          *bus;
        u8                      busn_start;
+       u8                      first_vec;
 };
 
 static inline struct vmd_dev *vmd_from_bus(struct pci_bus *bus)
@@ -199,11 +206,11 @@ static irq_hw_number_t vmd_get_hwirq(struct msi_domain_info *info,
  */
 static struct vmd_irq_list *vmd_next_irq(struct vmd_dev *vmd, struct msi_desc *desc)
 {
-       int i, best = 1;
        unsigned long flags;
+       int i, best;
 
-       if (vmd->msix_count == 1)
-               return &vmd->irqs[0];
+       if (vmd->msix_count == 1 + vmd->first_vec)
+               return &vmd->irqs[vmd->first_vec];
 
        /*
         * White list for fast-interrupt handlers. All others will share the
@@ -213,11 +220,12 @@ static struct vmd_irq_list *vmd_next_irq(struct vmd_dev *vmd, struct msi_desc *d
        case PCI_CLASS_STORAGE_EXPRESS:
                break;
        default:
-               return &vmd->irqs[0];
+               return &vmd->irqs[vmd->first_vec];
        }
 
        raw_spin_lock_irqsave(&list_lock, flags);
-       for (i = 1; i < vmd->msix_count; i++)
+       best = vmd->first_vec + 1;
+       for (i = best; i < vmd->msix_count; i++)
                if (vmd->irqs[i].count < vmd->irqs[best].count)
                        best = i;
        vmd->irqs[best].count++;
@@ -550,8 +558,8 @@ static int vmd_alloc_irqs(struct vmd_dev *vmd)
        if (vmd->msix_count < 0)
                return -ENODEV;
 
-       vmd->msix_count = pci_alloc_irq_vectors(dev, 1, vmd->msix_count,
-                                               PCI_IRQ_MSIX);
+       vmd->msix_count = pci_alloc_irq_vectors(dev, vmd->first_vec + 1,
+                                               vmd->msix_count, PCI_IRQ_MSIX);
        if (vmd->msix_count < 0)
                return vmd->msix_count;
 
@@ -719,6 +727,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 
 static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
+       unsigned long features = (unsigned long) id->driver_data;
        struct vmd_dev *vmd;
        int err;
 
@@ -743,13 +752,16 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
            dma_set_mask_and_coherent(&dev->dev, DMA_BIT_MASK(32)))
                return -ENODEV;
 
+       if (features & VMD_FEAT_OFFSET_FIRST_VECTOR)
+               vmd->first_vec = 1;
+
        err = vmd_alloc_irqs(vmd);
        if (err)
                return err;
 
        spin_lock_init(&vmd->cfg_lock);
        pci_set_drvdata(dev, vmd);
-       err = vmd_enable_domain(vmd, (unsigned long) id->driver_data);
+       err = vmd_enable_domain(vmd, features);
        if (err)
                return err;
 
@@ -818,13 +830,16 @@ static const struct pci_device_id vmd_ids[] = {
                                VMD_FEAT_HAS_BUS_RESTRICTIONS,},
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x467f),
                .driver_data = VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |
-                               VMD_FEAT_HAS_BUS_RESTRICTIONS,},
+                               VMD_FEAT_HAS_BUS_RESTRICTIONS |
+                               VMD_FEAT_OFFSET_FIRST_VECTOR,},
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x4c3d),
                .driver_data = VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |
-                               VMD_FEAT_HAS_BUS_RESTRICTIONS,},
+                               VMD_FEAT_HAS_BUS_RESTRICTIONS |
+                               VMD_FEAT_OFFSET_FIRST_VECTOR,},
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_VMD_9A0B),
                .driver_data = VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |
-                               VMD_FEAT_HAS_BUS_RESTRICTIONS,},
+                               VMD_FEAT_HAS_BUS_RESTRICTIONS |
+                               VMD_FEAT_OFFSET_FIRST_VECTOR,},
        {0,}
 };
 MODULE_DEVICE_TABLE(pci, vmd_ids);