[PATCH] PCI/VMD: Fix config addressing with bus offsets

[Jon Derrick <jonathan.derrick@xxxxxxxxx>]

VMD config space addressing relies on mapping the BDF of the target into
the VMD config bar. When using bus number offsets to number the VMD
domain, the offset needs to be ignored in order to correctly map devices
to their config space.

Fixes: 2a5a9c9a20f9 ("PCI: vmd: Add offset to bus numbers if necessary")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.18+
Signed-off-by: Jon Derrick <jonathan.derrick@xxxxxxxxx>
---
 drivers/pci/controller/vmd.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 999a5509e57e..6c80b9098dd0 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -94,6 +94,7 @@ struct vmd_dev {
 	struct resource		resources[3];
 	struct irq_domain	*irq_domain;
 	struct pci_bus		*bus;
+	u8			busn_start;
 
 	struct dma_map_ops	dma_ops;
 	struct dma_domain	dma_domain;
@@ -440,7 +441,8 @@ static char __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
 				  unsigned int devfn, int reg, int len)
 {
 	char __iomem *addr = vmd->cfgbar +
-			     (bus->number << 20) + (devfn << 12) + reg;
+			     ((bus->number - vmd->busn_start) << 20) +
+			     (devfn << 12) + reg;
 
 	if ((addr - vmd->cfgbar) + len >=
 	    resource_size(&vmd->dev->resource[VMD_CFGBAR]))
@@ -563,7 +565,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	unsigned long flags;
 	LIST_HEAD(resources);
 	resource_size_t offset[2] = {0};
-	resource_size_t membar2_offset = 0x2000, busn_start = 0;
+	resource_size_t membar2_offset = 0x2000;
 	struct pci_bus *child;
 
 	/*
@@ -606,14 +608,14 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 		pci_read_config_dword(vmd->dev, PCI_REG_VMCONFIG, &vmconfig);
 		if (BUS_RESTRICT_CAP(vmcap) &&
 		    (BUS_RESTRICT_CFG(vmconfig) == 0x1))
-			busn_start = 128;
+			vmd->busn_start = 128;
 	}
 
 	res = &vmd->dev->resource[VMD_CFGBAR];
 	vmd->resources[0] = (struct resource) {
 		.name  = "VMD CFGBAR",
-		.start = busn_start,
-		.end   = busn_start + (resource_size(res) >> 20) - 1,
+		.start = vmd->busn_start,
+		.end   = vmd->busn_start + (resource_size(res) >> 20) - 1,
 		.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
 	};
 
@@ -681,8 +683,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
 	pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
 
-	vmd->bus = pci_create_root_bus(&vmd->dev->dev, busn_start, &vmd_ops,
-				       sd, &resources);
+	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
+				       &vmd_ops, sd, &resources);
 	if (!vmd->bus) {
 		pci_free_resource_list(&resources);
 		irq_domain_remove(vmd->irq_domain);
-- 
2.20.1