vfio/pci: Extract mdev check into an helper

In preparation to skip initialization of the HostIOMMUDevice for mdev,
extract the checks that validate if a device is an mdev into helpers.

A vfio_device_is_mdev() is created, and subsystems consult VFIODevice::mdev
to check if it's mdev or not.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

1 files changed, 3 insertions, 9 deletions

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index e03d9f3ba5..b34e91468a 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2963,12 +2963,9 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     ERRP_GUARD();
     VFIOPCIDevice *vdev = VFIO_PCI(pdev);
     VFIODevice *vbasedev = &vdev->vbasedev;
-    char *subsys;
     int i, ret;
-    bool is_mdev;
     char uuid[UUID_STR_LEN];
     g_autofree char *name = NULL;
-    g_autofree char *tmp = NULL;
 
     if (vbasedev->fd < 0 && !vbasedev->sysfsdev) {
         if (!(~vdev->host.domain || ~vdev->host.bus ||
@@ -2997,14 +2994,11 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
      * stays in sync with the active working set of the guest driver.  Prevent
      * the x-balloon-allowed option unless this is minimally an mdev device.
      */
-    tmp = g_strdup_printf("%s/subsystem", vbasedev->sysfsdev);
-    subsys = realpath(tmp, NULL);
-    is_mdev = subsys && (strcmp(subsys, "/sys/bus/mdev") == 0);
-    free(subsys);
+    vbasedev->mdev = vfio_device_is_mdev(vbasedev);
 
-    trace_vfio_mdev(vbasedev->name, is_mdev);
+    trace_vfio_mdev(vbasedev->name, vbasedev->mdev);
 
-    if (vbasedev->ram_block_discard_allowed && !is_mdev) {
+    if (vbasedev->ram_block_discard_allowed && !vbasedev->mdev) {
         error_setg(errp, "x-balloon-allowed only potentially compatible "
                    "with mdev devices");
         goto error;