[Xen-devel] [PATCH RFC 0/9] console improvements

["Jan Beulich" <JBeulich@xxxxxxxx>]

This series adds support for an EHCI debug port based console, and
does some other improvements and cleanup noticed to be desirable
during the implementation of the former as follow-up.

1: x86: allow early use of fixmaps
2: console: prepare for non-COMn port support
3: console: add EHCI debug port based serial console
4: serial: avoid fully initializing unused consoles
5: ns16550: MMIO adjustments
6: ns16550: PCI initialization adjustments
7: ns16550: command line parsing adjustments
8: PCI: bus scan adjustments
9: x86: construct static part of 1:1 mapping at build time

Note that this also requires a Dom0 kernel side enhancement,
which I'm reproducing below for reference (intending to submit
this only when the public interface change on the hypervisor
side is approved, which in turn will take its time due to the
current feature freeze).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/drivers/usb/early/ehci-dbgp.c
+++ b/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 @@ err:
                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 @@ try_next_port:
                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 cons
                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;
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -321,7 +321,7 @@ static int ehci_reset (struct ehci_hcd *
 
        /* 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;
@@ -345,7 +345,7 @@ static int ehci_reset (struct ehci_hcd *
                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;
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -347,10 +347,10 @@ static int ehci_bus_resume (struct usb_h
        }
 
        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
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -21,6 +21,7 @@ CFLAGS_features.o                     := $(nostackp)
 endif
 
 priv-$(CONFIG_PCI)                     := pci.o
+priv-$(CONFIG_USB_SUPPORT)             += dbgp.o
 
 obj-$(CONFIG_XEN)                      += features.o $(xen-backend-y) 
$(xen-backend-m)
 obj-$(CONFIG_XEN_PRIVILEGED_GUEST)     += $(priv-y)
@@ -37,7 +38,7 @@ obj-$(CONFIG_XEN_SYS_HYPERVISOR)      += sys-
 obj-$(CONFIG_XEN_PVHVM)                        += platform-pci.o
 obj-$(CONFIG_XEN_TMEM)                 += tmem.o
 obj-$(CONFIG_SWIOTLB_XEN)              += swiotlb-xen.o
-obj-$(CONFIG_XEN_DOM0)                 += pci.o
+obj-$(CONFIG_XEN_DOM0)                 += pci.o dbgp.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)       += xen-pciback/
 obj-$(CONFIG_XEN_PRIVCMD)              += $(xen-privcmd_y)
 obj-$(CONFIG_XEN_ACPI_PROCESSOR)       += xen-acpi-processor.o
--- /dev/null
+++ b/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
--- a/include/linux/usb/ehci_def.h
+++ b/include/linux/usb/ehci_def.h
@@ -207,18 +207,35 @@ extern int __init early_dbgp_init(char *
 extern struct console early_dbgp_console;
 #endif /* CONFIG_EARLY_PRINTK_DBGP */
 
+struct usb_hcd;
+
+#if defined(CONFIG_XEN_PRIVILEGED_GUEST) || defined(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
 
--- a/include/xen/interface/physdev.h
+++ b/include/xen/interface/physdev.h
@@ -307,6 +307,24 @@ struct physdev_pci_device {
 typedef struct physdev_pci_device physdev_pci_device_t;
 DEFINE_XEN_GUEST_HANDLE(physdev_pci_device_t);
 
+#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;
+};
+typedef struct physdev_dbgp_op physdev_dbgp_op_t;
+DEFINE_XEN_GUEST_HANDLE(physdev_dbgp_op_t);
+
 /*
  * Notify that some PIRQ-bound event channels have been unmasked.
  * ** This command is obsolete since interface version 0x00030202 and is **


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