xen: add and enable Xen console for PVH guests

This adds and enables the PV console used on XEN kernels to
GENERIC/XENHVM kernels in order for it to be used on PVH.

Approved by: gibbs
Sponsored by: Citrix Systems R&D

dev/xen/console/console.c:
 - Define console_page.
 - Move xc_printf debug function from i386 XEN code to generic console
   code.
 - Rework xc_printf.
 - Use xen_initial_domain instead of open-coded checks for Dom0.
 - Gate the attach of the PV console to PV(H) guests.

dev/xen/console/xencons_ring.c:
 - Allow the PV Xen console to output earlier by directly signaling
   the event channel in start_info if the event channel is not yet
   initialized.
 - Use HYPERVISOR_start_info instead of xen_start_info.

i386/include/xen/xen-os.h:
 - Remove prototype for xc_printf since it's now declared in global
   xen-os.h

i386/xen/xen_machdep.c:
 - Remove previous version of xc_printf.
 - Remove definition of console_page (now it's defined in the console
   itself).
 - Fix some printf formatting errors.

x86/xen/pv.c:
 - Add some early boot debug messages using xc_printf.
 - Set console_page based on the value passed in start_info.

xen/xen-os.h:
 - Declare console_page and add prototype for xc_printf.

2 files changed, 88 insertions, 13 deletions

diff --git a/sys/dev/xen/console/console.c b/sys/dev/xen/console/console.c
index dfabd70..f151ca6 100644
--- a/sys/dev/xen/console/console.c
+++ b/sys/dev/xen/console/console.c
@@ -27,6 +27,8 @@ __FBSDID("$FreeBSD$");
 
 
 #include "opt_ddb.h"
+#include "opt_printf.h"
+
 #ifdef DDB
 #include <ddb/ddb.h>
 #endif
@@ -69,11 +71,14 @@ struct mtx              cn_mtx;
 static char wbuf[WBUF_SIZE];
 static char rbuf[RBUF_SIZE];
 static int rc, rp;
-static unsigned int cnsl_evt_reg;
+bool cnsl_evt_reg;
 static unsigned int wc, wp; /* write_cons, write_prod */
 xen_intr_handle_t xen_intr_handle;
 device_t xencons_dev;
 
+/* Virtual address of the shared console page */
+char *console_page;
+
 #ifdef KDB
 static int	xc_altbrk;
 #endif
@@ -110,9 +115,70 @@ static struct ttydevsw xc_ttydevsw = {
         .tsw_outwakeup	= xcoutwakeup,
 };
 
+/*----------------------------- Debug function -------------------------------*/
+struct putchar_arg {
+	char	*buf;
+	size_t	size;
+	size_t	n_next;
+};
+
+static void
+putchar(int c, void *arg)
+{
+	struct putchar_arg *pca;
+
+	pca = (struct putchar_arg *)arg;
+
+	if (pca->buf == NULL) {
+		/*
+		 * We have no buffer, output directly to the
+		 * console char by char.
+		 */
+		HYPERVISOR_console_write((char *)&c, 1);
+	} else {
+		pca->buf[pca->n_next++] = c;
+		if ((pca->size == pca->n_next) || (c = '\0')) {
+			/* Flush the buffer */
+			HYPERVISOR_console_write(pca->buf, pca->n_next);
+			pca->n_next = 0;
+		}
+	}
+}
+
+void
+xc_printf(const char *fmt, ...)
+{
+	va_list ap;
+	struct putchar_arg pca;
+#ifdef PRINTF_BUFR_SIZE
+	char buf[PRINTF_BUFR_SIZE];
+
+	pca.buf = buf;
+	pca.size = sizeof(buf);
+	pca.n_next = 0;
+#else
+	pca.buf = NULL;
+	pca.size = 0;
+#endif
+
+	KASSERT((xen_domain()), ("call to xc_printf from non Xen guest"));
+
+	va_start(ap, fmt);
+	kvprintf(fmt, putchar, &pca, 10, ap);
+	va_end(ap);
+
+#ifdef PRINTF_BUFR_SIZE
+	if (pca.n_next != 0)
+		HYPERVISOR_console_write(buf, pca.n_next);
+#endif
+}
+
 static void
 xc_cnprobe(struct consdev *cp)
 {
+	if (!xen_pv_domain())
+		return;
+
 	cp->cn_pri = CN_REMOTE;
 	sprintf(cp->cn_name, "%s0", driver_name);
 }
@@ -175,7 +241,7 @@ static void
 xc_cnputc(struct consdev *dev, int c)
 {
 
-	if (xen_start_info->flags & SIF_INITDOMAIN)
+	if (xen_initial_domain())
 		xc_cnputc_dom0(dev, c);
 	else
 		xc_cnputc_domu(dev, c);
@@ -206,8 +272,7 @@ xcons_putc(int c)
 		xcons_force_flush();
 #endif	    	
 	}
-	if (cnsl_evt_reg)
-		__xencons_tx_flush();
+	__xencons_tx_flush();
 	
 	/* inform start path that we're pretty full */
 	return ((wp - wc) >= WBUF_SIZE - 100) ? TRUE : FALSE;
@@ -217,6 +282,10 @@ static void
 xc_identify(driver_t *driver, device_t parent)
 {
 	device_t child;
+
+	if (!xen_pv_domain())
+		return;
+
 	child = BUS_ADD_CHILD(parent, 0, driver_name, 0);
 	device_set_driver(child, driver);
 	device_set_desc(child, "Xen Console");
@@ -242,10 +311,10 @@ xc_attach(device_t dev)
 
 	xencons_ring_init();
 
-	cnsl_evt_reg = 1;
+	cnsl_evt_reg = true;
 	callout_reset(&xc_callout, XC_POLLTIME, xc_timeout, xccons);
     
-	if (xen_start_info->flags & SIF_INITDOMAIN) {
+	if (xen_initial_domain()) {
 		error = xen_intr_bind_virq(dev, VIRQ_CONSOLE, 0, NULL,
 		                           xencons_priv_interrupt, NULL,
 		                           INTR_TYPE_TTY, &xen_intr_handle);
@@ -309,7 +378,7 @@ __xencons_tx_flush(void)
 		sz = wp - wc;
 		if (sz > (WBUF_SIZE - WBUF_MASK(wc)))
 			sz = WBUF_SIZE - WBUF_MASK(wc);
-		if (xen_start_info->flags & SIF_INITDOMAIN) {
+		if (xen_initial_domain()) {
 			HYPERVISOR_console_io(CONSOLEIO_write, sz, &wbuf[WBUF_MASK(wc)]);
 			wc += sz;
 		} else {
@@ -426,7 +495,7 @@ xcons_force_flush(void)
 {
 	int        sz;
 
-	if (xen_start_info->flags & SIF_INITDOMAIN)
+	if (xen_initial_domain())
 		return;
 
 	/* Spin until console data is flushed through to the domain controller. */
diff --git a/sys/dev/xen/console/xencons_ring.c b/sys/dev/xen/console/xencons_ring.c
index 3701551..42b9abe 100644
--- a/sys/dev/xen/console/xencons_ring.c
+++ b/sys/dev/xen/console/xencons_ring.c
@@ -32,9 +32,9 @@ __FBSDID("$FreeBSD$");
 
 #define console_evtchn	console.domU.evtchn
 xen_intr_handle_t console_handle;
-extern char *console_page;
 extern struct mtx              cn_mtx;
 extern device_t xencons_dev;
+extern bool cnsl_evt_reg;
 
 static inline struct xencons_interface *
 xencons_interface(void)
@@ -60,6 +60,9 @@ xencons_ring_send(const char *data, unsigned len)
 	struct xencons_interface *intf; 
 	XENCONS_RING_IDX cons, prod;
 	int sent;
+	struct evtchn_send send = {
+		.port = HYPERVISOR_start_info->console_evtchn
+	};
 
 	intf = xencons_interface();
 	cons = intf->out_cons;
@@ -76,7 +79,10 @@ xencons_ring_send(const char *data, unsigned len)
 	wmb();
 	intf->out_prod = prod;
 
-	xen_intr_signal(console_handle);
+	if (cnsl_evt_reg)
+		xen_intr_signal(console_handle);
+	else
+		HYPERVISOR_event_channel_op(EVTCHNOP_send, &send);
 
 	return sent;
 
@@ -125,11 +131,11 @@ xencons_ring_init(void)
 {
 	int err;
 
-	if (!xen_start_info->console_evtchn)
+	if (HYPERVISOR_start_info->console_evtchn == 0)
 		return 0;
 
 	err = xen_intr_bind_local_port(xencons_dev,
-	    xen_start_info->console_evtchn, NULL, xencons_handle_input, NULL,
+	    HYPERVISOR_start_info->console_evtchn, NULL, xencons_handle_input, NULL,
 	    INTR_TYPE_MISC | INTR_MPSAFE, &console_handle);
 	if (err) {
 		return err;
@@ -145,7 +151,7 @@ void
 xencons_suspend(void)
 {
 
-	if (!xen_start_info->console_evtchn)
+	if (HYPERVISOR_start_info->console_evtchn == 0)
 		return;
 
 	xen_intr_unbind(&console_handle);