hvc_xen: fix xenboot for DomUs

The xenboot early console has been partially broken for DomU for a long
time: the output would only go to the hypervisor via hypercall
(HYPERVISOR_console_io), while it wouldn't actually go to the DomU
console. The reason is that domU_write_console would return early as no
xencons structs are configured for it.

Add an appropriate xencons struct for xenboot from the xenboot setup
callback.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 68b8ec886becc9bdac6c1bbdd4b36ee7d2c483f3..f34dec1d588a177bc4c0921ea4556aeb9e63d101 100644 (file)
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -246,6 +246,18 @@ err:
        return -ENODEV;
 }
 
+static int xencons_info_pv_init(struct xencons_info *info, int vtermno)
+{
+       info->evtchn = xen_start_info->console.domU.evtchn;
+       /* GFN == MFN for PV guest */
+       info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
+       info->vtermno = vtermno;
+
+       list_add_tail(&info->list, &xenconsoles);
+
+       return 0;
+}
+
 static int xen_pv_console_init(void)
 {
        struct xencons_info *info;
@@ -265,13 +277,8 @@ static int xen_pv_console_init(void)
                /* already configured */
                return 0;
        }
-       info->evtchn = xen_start_info->console.domU.evtchn;
-       /* GFN == MFN for PV guest */
-       info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
-       info->vtermno = HVC_COOKIE;
-
        spin_lock(&xencons_lock);
-       list_add_tail(&info->list, &xenconsoles);
+       xencons_info_pv_init(info, HVC_COOKIE);
        spin_unlock(&xencons_lock);
 
        return 0;
@@ -599,6 +606,18 @@ static int xen_cons_init(void)
 console_initcall(xen_cons_init);
 
 #ifdef CONFIG_EARLY_PRINTK
+static int __init xenboot_setup_console(struct console *console, char *string)
+{
+       static struct xencons_info xenboot;
+
+       if (xen_initial_domain())
+               return 0;
+       if (!xen_pv_domain())
+               return -ENODEV;
+
+       return xencons_info_pv_init(&xenboot, 0);
+}
+
 static void xenboot_write_console(struct console *console, const char *string,
                                  unsigned len)
 {
@@ -629,6 +648,7 @@ static void xenboot_write_console(struct console *console, const char *string,
 struct console xenboot_console = {
        .name           = "xenboot",
        .write          = xenboot_write_console,
+       .setup          = xenboot_setup_console,
        .flags          = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
        .index          = -1,
 };