diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index da3f0ed18c76..c94167d87178 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -729,6 +729,7 @@ static long vfio_pci_ioctl(void *device_data,
 		{
 			void __iomem *io;
 			size_t size;
+			u16 orig_cmd;
 
 			info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
 			info.flags = 0;
@@ -744,15 +745,23 @@ static long vfio_pci_ioctl(void *device_data,
 					break;
 			}
 
-			/* Is it really there? */
-			io = pci_map_rom(pdev, &size);
-			if (!io || !size) {
-				info.size = 0;
-				break;
-			}
-			pci_unmap_rom(pdev, io);
+			/*
+			 * Is it really there?  Enable memory decode for
+			 * implicit access in pci_map_rom().
+			 */
+			pci_read_config_word(pdev, PCI_COMMAND, &orig_cmd);
+			pci_write_config_word(pdev, PCI_COMMAND,
+					      orig_cmd | PCI_COMMAND_MEMORY);
 
-			info.flags = VFIO_REGION_INFO_FLAG_READ;
+			io = pci_map_rom(pdev, &size);
+			if (io) {
+				info.flags = VFIO_REGION_INFO_FLAG_READ;
+				pci_unmap_rom(pdev, io);
+			} else {
+				info.size = 0;
+			}
+
+			pci_write_config_word(pdev, PCI_COMMAND, orig_cmd);
 			break;
 		}
 		case VFIO_PCI_VGA_REGION_INDEX: