[v3,16/24] xen/console: introduce console_write()

Commit Message

Denis Mukhin via B4 Relay Jan. 4, 2025, 1:58 a.m. UTC

From: Denis Mukhin <[e-mail]>

PV Linux kernel uses HYPERVISOR_console_io hypercall for early console which
ends up being handled by Xen's console driver's guest_console_write().

guest_console_write() duplicates the code from __putstr(), elimitate code
duplication.

Signed-off-by: Denis Mukhin <[e-mail]>
---
 xen/drivers/char/console.c | 103 ++++++++++++++++++++++++---------------------
 1 file changed, 55 insertions(+), 48 deletions(-)

Patch

diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index a33132b8fad95a1ad7e0aab4aef3fa3e46a5c03a..2f776b2f07cb15fae8060f3574db73234a38727a 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -40,6 +40,11 @@ 
 #include <asm/guest.h>
 #endif
 
+/* Console flags. */
+enum {
+    CONSOLE_RING    = BIT(0, U),
+};
+
 /* console: comma-separated list of console outputs. */
 static char __initdata opt_console[30] = OPT_CONSOLE_STR;
 string_param("console", opt_console);
@@ -636,6 +641,16 @@  static void cf_check notify_dom0_con_ring(void *unused)
 static DECLARE_SOFTIRQ_TASKLET(notify_dom0_con_ring_tasklet,
                                notify_dom0_con_ring, NULL);
 
+static bool console_locks_busted;
+
+static void conring_write(const char *str, size_t len)
+{
+    conring_puts(str, len);
+
+    if ( !console_locks_busted )
+        tasklet_schedule(&notify_dom0_con_ring_tasklet);
+}
+
 #ifdef CONFIG_X86
 static inline void xen_console_write_debug_port(const char *buf, size_t len)
 {
@@ -644,8 +659,47 @@  static inline void xen_console_write_debug_port(const char *buf, size_t len)
                    : "=&S" (tmp), "=&c" (tmp)
                    : "0" (buf), "1" (len), "d" (XEN_HVM_DEBUGCONS_IOPORT) );
 }
+
+static void xen_console_write(const char *str, size_t len)
+{
+    if ( xen_guest )
+        xen_hypercall_console_write(str, len);
+    else
+        xen_console_write_debug_port(str, len);
+}
 #endif
 
+/*
+ * Write characters to console.
+ *
+ * That will handle all possible scenarios working w/ console
+ * - serial console;
+ * - VGA console (x86 only);
+ * - __HYPERVISOR_console_io hypercall (x86 only);
+ * - debug I/O port (x86 only);
+ * - PV console.
+ */
+static void console_write(const char *str, size_t len, unsigned int flags)
+{
+    ASSERT(rspin_is_locked(&console_lock));
+
+    console_serial_puts(str, len);
+    video_puts(str, len);
+
+#ifdef CONFIG_X86
+    if ( opt_console_xen )
+        xen_console_write(str, len);
+#endif
+
+    if ( flags & CONSOLE_RING )
+        conring_write(str, len);
+}
+
+static inline void __putstr(const char *str)
+{
+    console_write(str, strlen(str), CONSOLE_RING);
+}
+
 static long guest_console_write(XEN_GUEST_HANDLE_PARAM(char) buffer,
                                 unsigned int count)
 {
@@ -666,28 +720,8 @@  static long guest_console_write(XEN_GUEST_HANDLE_PARAM(char) buffer,
 
         if ( is_hardware_domain(cd) )
         {
-            /* Use direct console output as it could be interactive */
             nrspin_lock_irq(&console_lock);
-
-            console_serial_puts(kbuf, kcount);
-            video_puts(kbuf, kcount);
-
-#ifdef CONFIG_X86
-            if ( opt_console_xen )
-            {
-                if ( xen_guest )
-                    xen_hypercall_console_write(kbuf, kcount);
-                else
-                    xen_console_write_debug_port(kbuf, kcount);
-            }
-#endif
-
-            if ( opt_console_to_ring )
-            {
-                conring_puts(kbuf, kcount);
-                tasklet_schedule(&notify_dom0_con_ring_tasklet);
-            }
-
+            console_write(kbuf, kcount, !!opt_console_to_ring);
             nrspin_unlock_irq(&console_lock);
         }
         else
@@ -788,33 +822,6 @@  long do_console_io(
  * *****************************************************
  */
 
-static bool console_locks_busted;
-
-static void __putstr(const char *str)
-{
-    size_t len = strlen(str);
-
-    ASSERT(rspin_is_locked(&console_lock));
-
-    console_serial_puts(str, len);
-    video_puts(str, len);
-
-#ifdef CONFIG_X86
-    if ( opt_console_xen )
-    {
-        if ( xen_guest )
-            xen_hypercall_console_write(str, len);
-        else
-            xen_console_write_debug_port(str, len);
-    }
-#endif
-
-    conring_puts(str, len);
-
-    if ( !console_locks_busted )
-        tasklet_schedule(&notify_dom0_con_ring_tasklet);
-}
-
 static int printk_prefix_check(char *p, char **pp)
 {
     int loglvl = -1;