USB EHCI/Xen: propagate controller reset information to hypervisor

Just like for the in-tree early console debug port driver, the
hypervisor - when using a debug port based console - also needs to be
told about controller resets, so it can suppress using and then
re-initialize the debug port accordingly.

Other than the in-tree driver, the hypervisor driver actually cares
about doing this only for the device where the debug is port actually
in use, i.e. it needs to be told the coordinates of the device being
reset (quite obviously, leveraging the addition done for that would
likely benefit the in-tree driver too).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/early/ehci-dbgp.c

@@ -491,7 +491,7 @@ static int ehci_wait_for_port(int port);
  * Return -ENODEV for any general failure
  * Return -EIO if wait for port fails
  */
-int dbgp_external_startup(void)
+static int _dbgp_external_startup(void)
 {
 	int devnum;
 	struct usb_debug_descriptor dbgp_desc;
@@ -613,6 +613,11 @@ int dbgp_external_startup(void)
 		goto try_again;
 	return -ENODEV;
 }
+
+int dbgp_external_startup(struct usb_hcd *hcd)
+{
+	return xen_dbgp_external_startup(hcd) ?: _dbgp_external_startup();
+}
 EXPORT_SYMBOL_GPL(dbgp_external_startup);
 
 static int ehci_reset_port(int port)
@@ -804,7 +809,7 @@ static int __init ehci_setup(void)
 		dbgp_ehci_status("ehci skip - already configured");
 	}
 
-	ret = dbgp_external_startup();
+	ret = _dbgp_external_startup();
 	if (ret == -EIO)
 		goto next_debug_port;
 
@@ -934,7 +939,7 @@ static void early_dbgp_write(struct console *con, const char *str, u32 n)
 		ctrl = readl(&ehci_debug->control);
 		if (!(ctrl & DBGP_ENABLED)) {
 			dbgp_not_safe = 1;
-			dbgp_external_startup();
+			_dbgp_external_startup();
 		} else {
 			cmd |= CMD_RUN;
 			writel(cmd, &ehci_regs->command);
@@ -974,10 +979,14 @@ struct console early_dbgp_console = {
 	.index =	-1,
 };
 
-int dbgp_reset_prep(void)
+int dbgp_reset_prep(struct usb_hcd *hcd)
 {
+	int ret = xen_dbgp_reset_prep(hcd);
 	u32 ctrl;
 
+	if (ret)
+		return ret;
+
 	dbgp_not_safe = 1;
 	if (!ehci_debug)
 		return 0;

drivers/usb/host/ehci-hcd.c

@@ -228,7 +228,7 @@ static int ehci_reset (struct ehci_hcd *ehci)
 
 	/* If the EHCI debug controller is active, special care must be
 	 * taken before and after a host controller reset */
-	if (ehci->debug && !dbgp_reset_prep())
+	if (ehci->debug && !dbgp_reset_prep(ehci_to_hcd(ehci)))
 		ehci->debug = NULL;
 
 	command |= CMD_RESET;
@@ -251,7 +251,7 @@ static int ehci_reset (struct ehci_hcd *ehci)
 		tdi_reset (ehci);
 
 	if (ehci->debug)
-		dbgp_external_startup();
+		dbgp_external_startup(ehci_to_hcd(ehci));
 
 	ehci->port_c_suspend = ehci->suspended_ports =
 			ehci->resuming_ports = 0;

drivers/usb/host/ehci-hub.c

@@ -353,10 +353,10 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
 		goto shutdown;
 
 	if (unlikely(ehci->debug)) {
-		if (!dbgp_reset_prep())
+		if (!dbgp_reset_prep(hcd))
 			ehci->debug = NULL;
 		else
-			dbgp_external_startup();
+			dbgp_external_startup(hcd);
 	}
 
 	/* Ideally and we've got a real resume here, and no port's power

drivers/xen/Makefile

@@ -18,7 +18,7 @@ obj-$(CONFIG_XEN_PVHVM)			+= platform-pci.o
 obj-$(CONFIG_XEN_TMEM)			+= tmem.o
 obj-$(CONFIG_SWIOTLB_XEN)		+= swiotlb-xen.o
 obj-$(CONFIG_XEN_DOM0)			+= pcpu.o
-obj-$(CONFIG_XEN_DOM0)			+= pci.o acpi.o
+obj-$(CONFIG_XEN_DOM0)			+= pci.o dbgp.o acpi.o
 obj-$(CONFIG_XEN_MCE_LOG)		+= mcelog.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)	+= xen-pciback/
 obj-$(CONFIG_XEN_PRIVCMD)		+= xen-privcmd.o

drivers/xen/dbgp.c

@@ -0,0 +1,48 @@
+#include <linux/pci.h>
+#include <linux/usb.h>
+#include <linux/usb/ehci_def.h>
+#include <linux/usb/hcd.h>
+#include <asm/xen/hypercall.h>
+#include <xen/interface/physdev.h>
+#include <xen/xen.h>
+
+static int xen_dbgp_op(struct usb_hcd *hcd, int op)
+{
+	const struct device *ctrlr = hcd_to_bus(hcd)->controller;
+	struct physdev_dbgp_op dbgp;
+
+	if (!xen_initial_domain())
+		return 0;
+
+	dbgp.op = op;
+
+#ifdef CONFIG_PCI
+	if (ctrlr->bus == &pci_bus_type) {
+		const struct pci_dev *pdev = to_pci_dev(ctrlr);
+
+		dbgp.u.pci.seg = pci_domain_nr(pdev->bus);
+		dbgp.u.pci.bus = pdev->bus->number;
+		dbgp.u.pci.devfn = pdev->devfn;
+		dbgp.bus = PHYSDEVOP_DBGP_BUS_PCI;
+	} else
+#endif
+		dbgp.bus = PHYSDEVOP_DBGP_BUS_UNKNOWN;
+
+	return HYPERVISOR_physdev_op(PHYSDEVOP_dbgp_op, &dbgp);
+}
+
+int xen_dbgp_reset_prep(struct usb_hcd *hcd)
+{
+	return xen_dbgp_op(hcd, PHYSDEVOP_DBGP_RESET_PREPARE);
+}
+
+int xen_dbgp_external_startup(struct usb_hcd *hcd)
+{
+	return xen_dbgp_op(hcd, PHYSDEVOP_DBGP_RESET_DONE);
+}
+
+#ifndef CONFIG_EARLY_PRINTK_DBGP
+#include <linux/export.h>
+EXPORT_SYMBOL_GPL(xen_dbgp_reset_prep);
+EXPORT_SYMBOL_GPL(xen_dbgp_external_startup);
+#endif

include/linux/usb/ehci_def.h

@@ -221,18 +221,35 @@ extern int __init early_dbgp_init(char *s);
 extern struct console early_dbgp_console;
 #endif /* CONFIG_EARLY_PRINTK_DBGP */
 
+struct usb_hcd;
+
+#ifdef CONFIG_XEN_DOM0
+extern int xen_dbgp_reset_prep(struct usb_hcd *);
+extern int xen_dbgp_external_startup(struct usb_hcd *);
+#else
+static inline int xen_dbgp_reset_prep(struct usb_hcd *hcd)
+{
+	return 1; /* Shouldn't this be 0? */
+}
+
+static inline int xen_dbgp_external_startup(struct usb_hcd *hcd)
+{
+	return -1;
+}
+#endif
+
 #ifdef CONFIG_EARLY_PRINTK_DBGP
 /* Call backs from ehci host driver to ehci debug driver */
-extern int dbgp_external_startup(void);
-extern int dbgp_reset_prep(void);
+extern int dbgp_external_startup(struct usb_hcd *);
+extern int dbgp_reset_prep(struct usb_hcd *hcd);
 #else
-static inline int dbgp_reset_prep(void)
+static inline int dbgp_reset_prep(struct usb_hcd *hcd)
 {
-	return 1;
+	return xen_dbgp_reset_prep(hcd);
 }
-static inline int dbgp_external_startup(void)
+static inline int dbgp_external_startup(struct usb_hcd *hcd)
 {
-	return -1;
+	return xen_dbgp_external_startup(hcd);
 }
 #endif
 

include/xen/interface/physdev.h

@@ -258,6 +258,22 @@ struct physdev_pci_device {
     uint8_t devfn;
 };
 
+#define PHYSDEVOP_DBGP_RESET_PREPARE    1
+#define PHYSDEVOP_DBGP_RESET_DONE       2
+
+#define PHYSDEVOP_DBGP_BUS_UNKNOWN      0
+#define PHYSDEVOP_DBGP_BUS_PCI          1
+
+#define PHYSDEVOP_dbgp_op               29
+struct physdev_dbgp_op {
+    /* IN */
+    uint8_t op;
+    uint8_t bus;
+    union {
+        struct physdev_pci_device pci;
+    } u;
+};
+
 /*
  * Notify that some PIRQ-bound event channels have been unmasked.
  * ** This command is obsolete since interface version 0x00030202 and is **