powerpc/powernv: don't enable SRIOV when VF BAR has non 64bit-prefetchable BAR

On PHB3, we enable SRIOV devices by mapping IOV BAR with M64 BARs. If a
SRIOV device's IOV BAR is not 64bit-prefetchable, this is not assigned from
64bit prefetchable window, which means M64 BAR can't work on it.

The reason is PCI bridges support only 2 memory windows and the kernel code
programs bridges in the way that one window is 32bit-nonprefetchable and
the other one is 64bit-prefetchable. So if devices' IOV BAR is 64bit and
non-prefetchable, it will be mapped into 32bit space and therefore M64
cannot be used for it.

This patch makes this explicit and truncate IOV resource in this case to
save MMIO space.
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/pci-ioda.c

@@ -872,9 +872,6 @@ static int pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
 		if (!res->flags || !res->parent)
 			continue;
 
-		if (!pnv_pci_is_mem_pref_64(res->flags))
-			continue;
-
 		/*
 		 * The actual IOV BAR range is determined by the start address
 		 * and the actual size for num_vfs VFs BAR.  This check is to
@@ -903,9 +900,6 @@ static int pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
 		if (!res->flags || !res->parent)
 			continue;
 
-		if (!pnv_pci_is_mem_pref_64(res->flags))
-			continue;
-
 		size = pci_iov_resource_size(dev, i + PCI_IOV_RESOURCES);
 		res2 = *res;
 		res->start += size * offset;
@@ -1263,9 +1257,6 @@ static int pnv_pci_vf_assign_m64(struct pci_dev *pdev, u16 num_vfs)
 		if (!res->flags || !res->parent)
 			continue;
 
-		if (!pnv_pci_is_mem_pref_64(res->flags))
-			continue;
-
 		for (j = 0; j < vf_groups; j++) {
 			do {
 				win = find_next_zero_bit(&phb->ioda.m64_bar_alloc,
@@ -1552,6 +1543,12 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
 	pdn = pci_get_pdn(pdev);
 
 	if (phb->type == PNV_PHB_IODA2) {
+		if (!pdn->vfs_expanded) {
+			dev_info(&pdev->dev, "don't support this SRIOV device"
+				" with non 64bit-prefetchable IOV BAR\n");
+			return -ENOSPC;
+		}
+
 		/* Calculate available PE for required VFs */
 		mutex_lock(&phb->ioda.pe_alloc_mutex);
 		pdn->offset = bitmap_find_next_zero_area(
@@ -2877,9 +2874,10 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
 		if (!res->flags || res->parent)
 			continue;
 		if (!pnv_pci_is_mem_pref_64(res->flags)) {
-			dev_warn(&pdev->dev, " non M64 VF BAR%d: %pR\n",
+			dev_warn(&pdev->dev, "Don't support SR-IOV with"
+					" non M64 VF BAR%d: %pR. \n",
 				 i, res);
-			continue;
+			goto truncate_iov;
 		}
 
 		size = pci_iov_resource_size(pdev, i + PCI_IOV_RESOURCES);
@@ -2898,11 +2896,6 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
 		res = &pdev->resource[i + PCI_IOV_RESOURCES];
 		if (!res->flags || res->parent)
 			continue;
-		if (!pnv_pci_is_mem_pref_64(res->flags)) {
-			dev_warn(&pdev->dev, "Skipping expanding VF BAR%d: %pR\n",
-				 i, res);
-			continue;
-		}
 
 		dev_dbg(&pdev->dev, " Fixing VF BAR%d: %pR to\n", i, res);
 		size = pci_iov_resource_size(pdev, i + PCI_IOV_RESOURCES);
@@ -2912,6 +2905,16 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
 			 i, res, mul);
 	}
 	pdn->vfs_expanded = mul;
+
+	return;
+
+truncate_iov:
+	/* To save MMIO space, IOV BAR is truncated. */
+	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
+		res = &pdev->resource[i + PCI_IOV_RESOURCES];
+		res->flags = 0;
+		res->end = res->start - 1;
+	}
 }
 #endif /* CONFIG_PCI_IOV */