powerpc/powernv: simplify the calculation of iov resource alignment

The alignment of IOV BAR on PowerNV platform is the total size of the IOV
BAR. No matter whether the IOV BAR is extended with number of
roundup_pow_of_two(total_vfs) or number of max PE number (256), the total
size could be calculated by (vfs_expanded * VF_BAR_size).

This patch simplifies the pnv_pci_iov_resource_alignment() by removing the
first case.
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

@@ -3129,17 +3129,21 @@ static resource_size_t pnv_pci_iov_resource_alignment(struct pci_dev *pdev,
 						      int resno)
 {
 	struct pci_dn *pdn = pci_get_pdn(pdev);
-	resource_size_t align, iov_align;
-
-	iov_align = resource_size(&pdev->resource[resno]);
-	if (iov_align)
-		return iov_align;
+	resource_size_t align;
 
+	/*
+	 * On PowerNV platform, IOV BAR is mapped by M64 BAR to enable the
+	 * SR-IOV. While from hardware perspective, the range mapped by M64
+	 * BAR should be size aligned.
+	 *
+	 * This function returns the total IOV BAR size if M64 BAR is in
+	 * Shared PE mode or just VF BAR size if not.
+	 */
 	align = pci_iov_resource_size(pdev, resno);
-	if (pdn->vfs_expanded)
-		return pdn->vfs_expanded * align;
-
+	if (!pdn->vfs_expanded)
 		return align;
+
+	return pdn->vfs_expanded * align;
 }
 #endif /* CONFIG_PCI_IOV */