[PATCH] powerpc/powernv: make sure the IOV BAR will not exceed limit after shifting

[Wei Yang]

The actual IOV BAR range is determined by the start address and the actual
size for vf_num VFs BAR. After shifting the IOV BAR, there would be a
chance the actual end address exceed the limit and overlap with other
devices.

This patch adds a check to make sure after shifting, the range will not
overlap with other devices.

Signed-off-by: Wei Yang <weiyang at linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c |   53 ++++++++++++++++++++++++++---
 1 file changed, 48 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 8456ae8..1a1e74b 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -854,16 +854,18 @@ static unsigned int pnv_ioda_dma_weight(struct pci_dev *dev)
 }
 
 #ifdef CONFIG_PCI_IOV
-static void pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
+static int pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
 {
 	struct pci_dn *pdn = pci_get_pdn(dev);
 	int i;
 	struct resource *res;
 	resource_size_t size;
+	u16 vf_num;
 
 	if (!dev->is_physfn)
-		return;
+		return -EINVAL;
 
+	vf_num = pdn->vf_pes;
 	for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
 		res = &dev->resource[i];
 		if (!res->flags || !res->parent)
@@ -875,11 +877,49 @@ static void pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
 		dev_info(&dev->dev, " Shifting VF BAR %pR to\n", res);
 		size = pci_iov_resource_size(dev, i);
 		res->start += size*offset;
-
 		dev_info(&dev->dev, "                 %pR\n", res);
+
+		/*
+		 * The actual IOV BAR range is determined by the start address
+		 * and the actual size for vf_num VFs BAR. The check here is
+		 * to make sure after shifting, the range will not overlap
+		 * with other device.
+		 */
+		if ((res->start + (size * vf_num)) > res->end) {
+			dev_err(&dev->dev, "VF BAR%d: %pR will conflict with"
+					" other device after shift\n");
+			goto failed;
+		}
+	}
+
+	for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
+		res = &dev->resource[i];
+		if (!res->flags || !res->parent)
+			continue;
+
+		if (!pnv_pci_is_mem_pref_64(res->flags))
+			continue;
+
 		pci_update_resource(dev, i);
 	}
 	pdn->max_vfs -= offset;
+	return 0;
+
+failed:
+	for (; i >= PCI_IOV_RESOURCES; i--) {
+		res = &dev->resource[i];
+		if (!res->flags || !res->parent)
+			continue;
+
+		if (!pnv_pci_is_mem_pref_64(res->flags))
+			continue;
+
+		dev_info(&dev->dev, " Shifting VF BAR %pR to\n", res);
+		size = pci_iov_resource_size(dev, i);
+		res->start += size*(-offset);
+		dev_info(&dev->dev, "                 %pR\n", res);
+	}
+	return -EBUSY;
 }
 #endif /* CONFIG_PCI_IOV */
 
@@ -1480,8 +1520,11 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 vf_num)
 		}
 
 		/* Do some magic shift */
-		if (pdn->m64_per_iov == 1)
-			pnv_pci_vf_resource_shift(pdev, pdn->offset);
+		if (pdn->m64_per_iov == 1) {
+			ret = pnv_pci_vf_resource_shift(pdev, pdn->offset);
+			if (ret)
+				goto m64_failed;
+		}
 	}
 
 	/* Setup VF PEs */
-- 
1.7.9.5