[PATCH v2] PCI: vmd: Offset Client VMD MSI/X vectors

[Jon Derrick <jonathan.derrick@xxxxxxxxx>]

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

Signed-off-by: Jon Derrick <jonathan.derrick@xxxxxxxxx>
---
 drivers/pci/controller/vmd.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index f69ef8c89f72..f8195bad79d1 100644
--- 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/X 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)
@@ -199,25 +206,26 @@ 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];
+		return &vmd->irqs[vmd->first_vec];
 
 	/*
-	 * White list for fast-interrupt handlers. All others will share the
+	 * Allow list for fast-interrupt handlers. All others will share the
 	 * "slow" interrupt vector.
 	 */
 	switch (msi_desc_to_pci_dev(desc)->class) {
 	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++;
@@ -629,6 +637,7 @@ static irqreturn_t vmd_irq(int irq, void *data)
 
 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 i, err;
 
@@ -653,12 +662,15 @@ 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;
+
 	vmd->msix_count = pci_msix_vec_count(dev);
 	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;
 
@@ -755,13 +767,16 @@ 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);
-- 
2.18.1