[Xen-devel] [PATCH RFC 15/15] xen: support console_switching between Dom0 and DomUs on ARM

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Today Ctrl-AAA is used to switch between Xen and Dom0. Extend the
mechanism to allow for switching between Xen, Dom0, and any of the
initial DomU created from Xen alongside Dom0 out of information provided
via device tree.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
CC: andrew.cooper3@xxxxxxxxxx
CC: George.Dunlap@xxxxxxxxxxxxx
CC: ian.jackson@xxxxxxxxxxxxx
CC: jbeulich@xxxxxxxx
CC: konrad.wilk@xxxxxxxxxx
CC: tim@xxxxxxx
CC: wei.liu2@xxxxxxxxxx
---
 xen/drivers/char/console.c | 49 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 34 insertions(+), 15 deletions(-)

diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index dc9e0bb..07a89c6 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -31,10 +31,13 @@
 #include <xen/early_printk.h>
 #include <xen/warning.h>
 #include <xen/pv_console.h>
+#include <asm/setup.h>
 
 #ifdef CONFIG_X86
 #include <xen/consoled.h>
 #include <asm/guest.h>
+#else
+#include <asm/vpl011.h>
 #endif
 
 /* console: comma-separated list of console outputs. */
@@ -389,29 +392,48 @@ static void dump_console_ring_key(unsigned char key)
     free_xenheap_pages(buf, order);
 }
 
-/* CTRL-<switch_char> switches input direction between Xen and DOM0. */
+/*
+ * CTRL-<switch_char> switches input direction between Xen, Dom0 and
+ * DomUs.
+ */
 #define switch_code (opt_conswitch[0]-'a'+1)
-static int __read_mostly xen_rx = 1; /* FALSE => input passed to domain 0. */
+static int __read_mostly xen_rx = 1; /* 1 => input passed to domain 0. */
 
 static void switch_serial_input(void)
 {
-    static char *input_str[2] = { "DOM0", "Xen" };
-    xen_rx = !xen_rx;
-    printk("*** Serial input -> %s", input_str[xen_rx]);
+    xen_rx++;
+    if ( xen_rx == max_init_domid + 1 )
+        xen_rx = 0;
+
+    if ( !xen_rx )
+        printk("*** Serial input xen_rx=%d -> %s", xen_rx, "Xen");
+    else
+        printk("*** Serial input xen_rx=%d -> DOM%d", xen_rx, xen_rx - 1);
+
     if ( switch_code )
-        printk(" (type 'CTRL-%c' three times to switch input to %s)",
-               opt_conswitch[0], input_str[!xen_rx]);
+        printk(" (type 'CTRL-%c' three times to switch input)",
+               opt_conswitch[0]);
     printk("\n");
 }
 
 static void __serial_rx(char c, struct cpu_user_regs *regs)
 {
-    if ( xen_rx )
+    if ( xen_rx == 0 )
         return handle_keypress(c, regs);
 
-    /* Deliver input to guest buffer, unless it is already full. */
-    if ( (serial_rx_prod-serial_rx_cons) != SERIAL_RX_SIZE )
-        serial_rx_ring[SERIAL_RX_MASK(serial_rx_prod++)] = c;
+    if ( xen_rx == 1 )
+    {
+        /* Deliver input to guest buffer, unless it is already full. */
+        if ( (serial_rx_prod-serial_rx_cons) != SERIAL_RX_SIZE )
+            serial_rx_ring[SERIAL_RX_MASK(serial_rx_prod++)] = c;
+    }
+#ifdef CONFIG_ARM
+    else
+    {
+        struct domain *d = get_domain_by_id(xen_rx - 1);
+        vpl011_read_char(d, c);
+    }
+#endif
     /* Always notify the guest: prevents receive path from getting stuck. */
     send_global_virq(VIRQ_CONSOLE);
 
@@ -925,7 +947,7 @@ void __init console_endboot(void)
      * a useful 'how to switch' message.
      */
     if ( opt_conswitch[1] == 'x' )
-        xen_rx = !xen_rx;
+        xen_rx = 0;
 
     register_keyhandler('w', dump_console_ring_key,
                         "synchronously dump console ring buffer (dmesg)", 0);
@@ -935,9 +957,6 @@ void __init console_endboot(void)
                             "decrease log level threshold", 0);
     register_irq_keyhandler('G', &do_toggle_guest,
                             "toggle host/guest log level adjustment", 0);
-
-    /* Serial input is directed to DOM0 by default. */
-    switch_serial_input();
 }
 
 int __init console_has(const char *device)
-- 
1.9.1


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