Index: usr.sbin/bhyve/pci_emul.h
===================================================================
--- usr.sbin/bhyve/pci_emul.h
+++ usr.sbin/bhyve/pci_emul.h
@@ -223,6 +223,7 @@
 	    uint64_t hostbase, enum pcibar_type type, uint64_t size);
 int	pci_emul_add_msicap(struct pci_devinst *pi, int msgnum);
 int	pci_emul_add_pciecap(struct pci_devinst *pi, int pcie_device_type);
+void	pci_emul_cmd_changed(struct pci_devinst *pi, uint16_t old);
 void	pci_generate_msi(struct pci_devinst *pi, int msgnum);
 void	pci_generate_msix(struct pci_devinst *pi, int msgnum);
 void	pci_lintr_assert(struct pci_devinst *pi);
Index: usr.sbin/bhyve/pci_emul.c
===================================================================
--- usr.sbin/bhyve/pci_emul.c
+++ usr.sbin/bhyve/pci_emul.c
@@ -1679,11 +1679,64 @@
 	}
 }
 
+/*
+ * Update device state in response to changes to the PCI command
+ * register.
+ */
+void
+pci_emul_cmd_changed(struct pci_devinst *pi, uint16_t old)
+{
+	int i;
+	uint16_t changed, new;
+
+	new = pci_get_cfgdata16(pi, PCIR_COMMAND);
+	changed = old ^ new;
+
+	/*
+	 * If the MMIO or I/O address space decoding has changed then
+	 * register/unregister all BARs that decode that address space.
+	 */
+	for (i = 0; i <= PCI_BARMAX; i++) {
+		switch (pi->pi_bar[i].type) {
+			case PCIBAR_NONE:
+			case PCIBAR_MEMHI64:
+				break;
+			case PCIBAR_IO:
+				/* I/O address space decoding changed? */
+				if (changed & PCIM_CMD_PORTEN) {
+					if (new & PCIM_CMD_PORTEN)
+						register_bar(pi, i);
+					else
+						unregister_bar(pi, i);
+				}
+				break;
+			case PCIBAR_MEM32:
+			case PCIBAR_MEM64:
+				/* MMIO address space decoding changed? */
+				if (changed & PCIM_CMD_MEMEN) {
+					if (new & PCIM_CMD_MEMEN)
+						register_bar(pi, i);
+					else
+						unregister_bar(pi, i);
+				}
+				break;
+			default:
+				assert(0);
+		}
+	}
+
+	/*
+	 * If INTx has been unmasked and is pending, assert the
+	 * interrupt.
+	 */
+	pci_lintr_update(pi);
+}
+
 static void
 pci_emul_cmdsts_write(struct pci_devinst *pi, int coff, uint32_t new, int bytes)
 {
-	int i, rshift;
-	uint32_t cmd, cmd2, changed, old, readonly;
+	int rshift;
+	uint32_t cmd, old, readonly;
 
 	cmd = pci_get_cfgdata16(pi, PCIR_COMMAND);	/* stash old value */
 
@@ -1702,47 +1755,7 @@
 	new |= (old & readonly);
 	CFGWRITE(pi, coff, new, bytes);			/* update config */
 
-	cmd2 = pci_get_cfgdata16(pi, PCIR_COMMAND);	/* get updated value */
-	changed = cmd ^ cmd2;
-
-	/*
-	 * If the MMIO or I/O address space decoding has changed then
-	 * register/unregister all BARs that decode that address space.
-	 */
-	for (i = 0; i <= PCI_BARMAX; i++) {
-		switch (pi->pi_bar[i].type) {
-			case PCIBAR_NONE:
-			case PCIBAR_MEMHI64:
-				break;
-			case PCIBAR_IO:
-				/* I/O address space decoding changed? */
-				if (changed & PCIM_CMD_PORTEN) {
-					if (porten(pi))
-						register_bar(pi, i);
-					else
-						unregister_bar(pi, i);
-				}
-				break;
-			case PCIBAR_MEM32:
-			case PCIBAR_MEM64:
-				/* MMIO address space decoding changed? */
-				if (changed & PCIM_CMD_MEMEN) {
-					if (memen(pi))
-						register_bar(pi, i);
-					else
-						unregister_bar(pi, i);
-				}
-				break;
-			default:
-				assert(0);
-		}
-	}
-
-	/*
-	 * If INTx has been unmasked and is pending, assert the
-	 * interrupt.
-	 */
-	pci_lintr_update(pi);
+	pci_emul_cmd_changed(pi, cmd);
 }
 
 static void
Index: usr.sbin/bhyve/pci_passthru.c
===================================================================
--- usr.sbin/bhyve/pci_passthru.c
+++ usr.sbin/bhyve/pci_passthru.c
@@ -639,6 +639,9 @@
 		goto done;
 	}
 
+	pci_set_cfgdata16(pi, PCIR_COMMAND, read_config(&sc->psc_sel,
+	    PCIR_COMMAND, 2));
+
 	error = 0;				/* success */
 done:
 	return (error);
@@ -815,6 +818,7 @@
 {
 	int error, msix_table_entries, i;
 	struct passthru_softc *sc;
+	uint16_t cmd_old;
 
 	sc = pi->pi_arg;
 
@@ -871,6 +875,14 @@
 #endif
 
 	write_config(&sc->psc_sel, coff, bytes, val);
+	if (coff == PCIR_COMMAND) {
+		cmd_old = pci_get_cfgdata16(pi, PCIR_COMMAND);
+		if (bytes == 1)
+			pci_set_cfgdata8(pi, PCIR_COMMAND, val);
+		else if (bytes == 2)
+			pci_set_cfgdata16(pi, PCIR_COMMAND, val);
+		pci_emul_cmd_changed(pi, cmd_old);
+	}
 
 	return (0);
 }