Index: sys/amd64/vmm/io/ppt.c
===================================================================
--- sys/amd64/vmm/io/ppt.c
+++ sys/amd64/vmm/io/ppt.c
@@ -356,25 +356,12 @@
 static void
 ppt_pci_reset(device_t dev)
 {
-	int ps;
 
 	if (pcie_flr(dev,
-		     max(pcie_get_max_completion_timeout(dev) / 1000, 10),
-		     true))
+	     max(pcie_get_max_completion_timeout(dev) / 1000, 10), true))
 		return;
 
-	/*
-	 * If FLR fails, attempt a power-management reset by cycling
-	 * the device in/out of D3 state.
-	 * PCI spec says we can only go into D3 state from D0 state.
-	 * Transition from D[12] into D0 before going to D3 state.
-	 */
-	ps = pci_get_powerstate(dev);
-	if (ps != PCI_POWERSTATE_D0 && ps != PCI_POWERSTATE_D3)
-		pci_set_powerstate(dev, PCI_POWERSTATE_D0);
-	if (pci_get_powerstate(dev) != PCI_POWERSTATE_D3)
-		pci_set_powerstate(dev, PCI_POWERSTATE_D3);
-	pci_set_powerstate(dev, ps);
+	pci_hard_reset(dev, false);
 }
 
 int
Index: sys/dev/pci/pci.c
===================================================================
--- sys/dev/pci/pci.c
+++ sys/dev/pci/pci.c
@@ -6365,6 +6365,135 @@
 	return (true);
 }
 
+static bool
+pcie_with_uplink_port(device_t dev, int *pcie_location)
+{
+	device_t bus, pcib;
+	devclass_t pci_class;
+	struct pci_devinfo *pdinfo;
+
+	pci_class = devclass_find("pci");
+	bus = device_get_parent(dev);
+	if (bus == NULL)
+		return (false);
+	if (device_get_devclass(bus) != pci_class)
+		return (false);
+	pcib = device_get_parent(bus);
+	if (pcib == NULL ||
+	    device_get_devclass(device_get_parent(pcib)) != pci_class)
+		return (false);
+	pdinfo = device_get_ivars(pcib);
+	if (pdinfo->cfg.pcie.pcie_location == 0)
+		return (false);
+	if (pdinfo->cfg.pcie.pcie_type != PCIEM_TYPE_DOWNSTREAM_PORT &&
+	    pdinfo->cfg.pcie.pcie_type != PCIEM_TYPE_ROOT_PORT)
+		return (false);
+	*pcie_location = pdinfo->cfg.pcie.pcie_location;
+	return (true);
+}
+
+/*
+ * Try link drop and retrain of the downstream port of upstream
+ * switch, for PCIe.  According to the PCIe 3.0 spec 6.6.1, this must
+ * cause Conventional Hot reset of the device in the slot.
+ * Alternative, for PCIe, could be the secondary bus reset initiatied
+ * on the upstream switch PCIR_BRIDGECTL_1, bit 6.
+ */
+static void
+pcie_link_reset(device_t port, int pcie_location)
+{
+	uint16_t v;
+
+	v = pci_read_config(port, pcie_location + PCIER_LINK_CTL, 2);
+	v |= PCIEM_LINK_CTL_LINK_DIS;
+	pci_write_config(port, pcie_location + PCIER_LINK_CTL, v, 2);
+	pause("pcier1", hz / 50); /* 20 ms */
+	v &= ~PCIEM_LINK_CTL_LINK_DIS;
+	v |= PCIEM_LINK_CTL_RETRAIN_LINK;
+	pci_write_config(port, pcie_location + PCIER_LINK_CTL, v, 2);
+	pause("pcier2", hz / 10); /* 100 ms */
+}
+
+/*
+ * Issue Conventional Hot reset, and if not possible (e.g. device is
+ * not PCIe or link reset failed), power reset.
+ */
+void
+pci_hard_reset(device_t dev, bool link_level)
+{
+	int pcie_location, ps;
+
+	pci_save_state(dev);
+	if (link_level && pcie_with_uplink_port(dev, &pcie_location)) {
+		pcie_link_reset(device_get_parent(device_get_parent(dev)),
+		    pcie_location);
+	} else {
+		/*
+		 * If not PCIe or link method is not allowed, try
+		 * power reset
+		 */
+		pci_save_state(dev);
+		ps = pci_get_powerstate(dev);
+		if (ps != PCI_POWERSTATE_D0 && ps != PCI_POWERSTATE_D3)
+			pci_set_powerstate(dev, PCI_POWERSTATE_D0);
+		pci_set_powerstate(dev, PCI_POWERSTATE_D3);
+		pci_set_powerstate(dev, ps);
+	}
+	pci_restore_state(dev);
+}
+
+/*
+ * Issue Conventional Hot reset to the device, while detaching drivers
+ * from the device itself and all sibling PCIe functions in the same
+ * slot.  PCI(e) configuration is saved around the reset.
+ *
+ * Typical Conventional reset affects all functions of multi-function
+ * device.  More, drivers accessing functions during the reset get
+ * very confused, and could corrupt the hardware state when it brought
+ * up from the cold.
+ */
+int
+pcie_down_port_link_reset(device_t dev)
+{
+	device_t bus, dev1, *children;
+	int error, i, nchildren, pcie_location;
+
+	error = EINVAL;
+	children = NULL;
+	nchildren = 0;
+		
+	mtx_lock(&Giant);
+	if (!pcie_with_uplink_port(dev, &pcie_location))
+		goto done;
+
+	bus = device_get_parent(dev);
+	error = device_get_children(bus, &children, &nchildren);
+	if (error != 0)
+		goto done;
+	for (i = 0; i < nchildren; i++) {
+		dev1 = children[i];
+		error = device_quiesce(dev1);
+		if (error == 0)
+			error = device_detach(dev1);
+		pci_save_state(dev1);
+	}
+
+	pcie_link_reset(device_get_parent(bus), pcie_location);
+
+	for (i = 0; i < nchildren; i++) {
+		dev1 = children[i];
+		pci_restore_state(dev1);
+		if (device_get_state(dev1) != DS_ATTACHED)
+			device_probe_and_attach(dev1);
+	}
+	error = 0;
+
+done:
+	mtx_unlock(&Giant);
+	free(children, M_TEMP);
+	return (error);
+}
+
 const struct pci_device_table *
 pci_match_device(device_t child, const struct pci_device_table *id, size_t nelt)
 {
Index: sys/dev/pci/pcivar.h
===================================================================
--- sys/dev/pci/pcivar.h
+++ sys/dev/pci/pcivar.h
@@ -671,6 +671,7 @@
 device_t pci_find_pcie_root_port(device_t dev);
 int	pci_get_max_payload(device_t dev);
 int	pci_get_max_read_req(device_t dev);
+void	pci_hard_reset(device_t dev, bool link_level);
 void	pci_restore_state(device_t dev);
 void	pci_save_state(device_t dev);
 int	pci_set_max_read_req(device_t dev, int size);
@@ -679,6 +680,7 @@
 uint32_t pcie_adjust_config(device_t dev, int reg, uint32_t mask,
 	    uint32_t value, int width);
 bool	pcie_flr(device_t dev, u_int max_delay, bool force);
+int	pcie_down_port_link_reset(device_t dev);
 int	pcie_get_max_completion_timeout(device_t dev);
 bool	pcie_wait_for_pending_transactions(device_t dev, u_int max_delay);