diff --git a/usr.sbin/bhyve/pci_passthru.h b/usr.sbin/bhyve/pci_passthru.h
--- a/usr.sbin/bhyve/pci_passthru.h
+++ b/usr.sbin/bhyve/pci_passthru.h
@@ -11,6 +11,13 @@
 
 #include "pci_emul.h"
 
+struct passthru_softc;
+
+typedef int (*cfgread_handler)(struct passthru_softc *sc,
+    struct pci_devinst *pi, int coff, int bytes, uint32_t *rv);
+typedef int (*cfgwrite_handler)(struct passthru_softc *sc,
+    struct pci_devinst *pi, int coff, int bytes, uint32_t val);
+
 struct passthru_softc {
 	struct pci_devinst *psc_pi;
 	/* ROM is handled like a BAR */
@@ -24,7 +31,16 @@
 		int capoff;
 	} psc_msix;
 	struct pcisel psc_sel;
+
+	cfgread_handler psc_pcir_rhandler[PCI_REGMAX + 1];
+	cfgwrite_handler psc_pcir_whandler[PCI_REGMAX + 1];
 };
 
 uint32_t read_config(const struct pcisel *sel, long reg, int width);
 void write_config(const struct pcisel *sel, long reg, int width, uint32_t data);
+int passthru_cfgread_default(struct passthru_softc *sc, struct pci_devinst *pi,
+    int coff, int bytes, uint32_t *rv);
+int passthru_cfgwrite_default(struct passthru_softc *sc, struct pci_devinst *pi,
+    int coff, int bytes, uint32_t val);
+int set_pcir_handler(struct passthru_softc *sc, int reg, int len,
+    cfgread_handler rhandler, cfgwrite_handler whandler);
diff --git a/usr.sbin/bhyve/pci_passthru.c b/usr.sbin/bhyve/pci_passthru.c
--- a/usr.sbin/bhyve/pci_passthru.c
+++ b/usr.sbin/bhyve/pci_passthru.c
@@ -628,6 +628,21 @@
 	return (error);
 }
 
+int
+set_pcir_handler(struct passthru_softc *sc, int reg, int len,
+    cfgread_handler rhandler, cfgwrite_handler whandler)
+{
+	if (reg > PCI_REGMAX || reg + len > PCI_REGMAX + 1)
+		return (-1);
+
+	for (int i = reg; i < reg + len; ++i) {
+		sc->psc_pcir_rhandler[i] = rhandler;
+		sc->psc_pcir_whandler[i] = whandler;
+	}
+
+	return 0;
+}
+
 static int
 passthru_legacy_config(nvlist_t *nvl, const char *opts)
 {
@@ -841,6 +856,14 @@
             get_config_value_node(nvl, "rom"))) != 0)
 		goto done;
 
+	/*
+	 * Default PCI config register to accessing the config register of the
+	 * physical device.
+	 */
+	if ((error = set_pcir_handler(sc, 0, PCI_REGMAX + 1,
+	    passthru_cfgread_default, passthru_cfgwrite_default)) != 0)
+		goto done;
+
 	error = 0;		/* success */
 done:
 	if (error) {
@@ -893,6 +916,13 @@
 
 	sc = pi->pi_arg;
 
+	return (sc->psc_pcir_rhandler[coff](sc, pi, coff, bytes, rv));
+}
+
+int
+passthru_cfgread_default(struct passthru_softc *sc,
+    struct pci_devinst *pi __unused, int coff, int bytes, uint32_t *rv)
+{
 	/*
 	 * PCI BARs and MSI capability is emulated.
 	 */
@@ -933,12 +963,20 @@
 static int
 passthru_cfgwrite(struct pci_devinst *pi, int coff, int bytes, uint32_t val)
 {
-	int error, msix_table_entries, i;
 	struct passthru_softc *sc;
-	uint16_t cmd_old;
 
 	sc = pi->pi_arg;
 
+	return (sc->psc_pcir_whandler[coff](sc, pi, coff, bytes, val));
+}
+
+int
+passthru_cfgwrite_default(struct passthru_softc *sc, struct pci_devinst *pi,
+    int coff, int bytes, uint32_t val)
+{
+	int error, msix_table_entries, i;
+	uint16_t cmd_old;
+
 	/*
 	 * PCI BARs are emulated
 	 */