dm: pci: unregister bars which are still enabled in pci_emul_free_bars

Guest OS for example Windows will disable bars before shutdown. Bars
are unregistered when they are disabled. Trying to unregister a bar
which has been unregistered causes a assertion. In pci_emul_free_bars
only those enabled bars should be unregistered.

Tracked-On: #2962
Signed-off-by: Jian Jun Chen <jian.jun.chen@intel.com>
Acked-by: Yin Fengwei <fengwei.yin@intel.com>

Author: chejianj

devicemodel/hw/pci/core.c

@@ -703,12 +703,23 @@ pci_emul_alloc_pbar(struct pci_vdev *pdi, int idx, uint64_t hostbase,
 void
 pci_emul_free_bars(struct pci_vdev *pdi)
 {
-	int i;
+	int i, enabled;
 
 	for (i = 0; i < PCI_BARMAX; i++) {
 		if ((pdi->bar[i].type != PCIBAR_NONE) &&
 			(pdi->bar[i].type != PCIBAR_MEMHI64)){
-			unregister_bar(pdi, i);
+			/*
+			 * Check whether the bar is enabled or not,
+			 * if it is disabled then it should have been
+			 * unregistered in pci_emul_cmdsts_write.
+			 */
+			if (pdi->bar[i].type == PCIBAR_IO)
+				enabled = porten(pdi);
+			else
+				enabled = memen(pdi);
+
+			if (enabled)
+				unregister_bar(pdi, i);
 			pdi->bar[i].type = PCIBAR_NONE;
 		}
 	}