[PATCH v3] hvc_xen: implement multiconsole support

[PATCH v3] hvc_xen: implement multiconsole support

[Stefano Stabellini]

This patch implements support for multiple consoles:
consoles other than the first one are setup using the traditional xenbus
and grant-table based mechanism.
We use a list to keep track of the allocated consoles, we don't
expect too many of them anyway.


Changes in v3:

- call hvc_remove before removing the console from xenconsoles;
- do not lock xencons_lock twice in the destruction path;
- use the DEFINE_XENBUS_DRIVER macro.


Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 drivers/tty/hvc/hvc_xen.c |  435 +++++++++++++++++++++++++++++++++++++++------
 1 files changed, 377 insertions(+), 58 deletions(-)

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index d5000aa..26090c7 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -23,6 +23,7 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/types.h>
+#include <linux/list.h>
 
 #include <asm/io.h>
 #include <asm/xen/hypervisor.h>
@@ -30,47 +31,67 @@
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
 #include <xen/hvm.h>
+#include <xen/grant_table.h>
 #include <xen/page.h>
 #include <xen/events.h>
 #include <xen/interface/io/console.h>
 #include <xen/hvc-console.h>
+#include <xen/xenbus.h>
 
 #include "hvc_console.h"
 
 #define HVC_COOKIE   0x58656e /* "Xen" in hex */
 
-static struct hvc_struct *hvc;
-static int xencons_irq;
+struct xencons_info {
+	struct list_head list;
+	struct xenbus_device *xbdev;
+	struct xencons_interface *intf;
+	unsigned int evtchn;
+	struct hvc_struct *hvc;
+	int irq;
+	int vtermno;
+	grant_ref_t gntref;
+};
+
+static LIST_HEAD(xenconsoles);
+static DEFINE_SPINLOCK(xencons_lock);
+static struct xenbus_driver xencons_driver;
 
 /* ------------------------------------------------------------------ */
 
-static unsigned long console_pfn = ~0ul;
-static unsigned int console_evtchn = ~0ul;
-static struct xencons_interface *xencons_if = NULL;
+static struct xencons_info *vtermno_to_xencons(int vtermno)
+{
+	struct xencons_info *entry, *n, *ret = NULL;
+
+	if (list_empty(&xenconsoles))
+			return NULL;
 
-static inline struct xencons_interface *xencons_interface(void)
+	list_for_each_entry_safe(entry, n, &xenconsoles, list) {
+		if (entry->vtermno == vtermno) {
+			ret  = entry;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static inline int xenbus_devid_to_vtermno(int devid)
 {
-	if (xencons_if != NULL)
-		return xencons_if;
-	if (console_pfn == ~0ul)
-		return mfn_to_virt(xen_start_info->console.domU.mfn);
-	else
-		return __va(console_pfn << PAGE_SHIFT);
+	return devid + HVC_COOKIE;
 }
 
-static inline void notify_daemon(void)
+static inline void notify_daemon(struct xencons_info *cons)
 {
 	/* Use evtchn: this is called early, before irq is set up. */
-	if (console_evtchn == ~0ul)
-		notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
-	else
-		notify_remote_via_evtchn(console_evtchn);
+	notify_remote_via_evtchn(cons->evtchn);
 }
 
-static int __write_console(const char *data, int len)
+static int __write_console(struct xencons_info *xencons,
+		const char *data, int len)
 {
-	struct xencons_interface *intf = xencons_interface();
 	XENCONS_RING_IDX cons, prod;
+	struct xencons_interface *intf = xencons->intf;
 	int sent = 0;
 
 	cons = intf->out_cons;
@@ -85,13 +106,16 @@ static int __write_console(const char *data, int len)
 	intf->out_prod = prod;
 
 	if (sent)
-		notify_daemon();
+		notify_daemon(xencons);
 	return sent;
 }
 
 static int domU_write_console(uint32_t vtermno, const char *data, int len)
 {
 	int ret = len;
+	struct xencons_info *cons = vtermno_to_xencons(vtermno);
+	if (cons == NULL)
+		return -EINVAL;
 
 	/*
 	 * Make sure the whole buffer is emitted, polling if
@@ -100,7 +124,7 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
 	 * kernel is crippled.
 	 */
 	while (len) {
-		int sent = __write_console(data, len);
+		int sent = __write_console(cons, data, len);
 		
 		data += sent;
 		len -= sent;
@@ -114,9 +138,13 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
 
 static int domU_read_console(uint32_t vtermno, char *buf, int len)
 {
-	struct xencons_interface *intf = xencons_interface();
+	struct xencons_interface *intf;
 	XENCONS_RING_IDX cons, prod;
 	int recv = 0;
+	struct xencons_info *xencons = vtermno_to_xencons(vtermno);
+	if (xencons == NULL)
+		return -EINVAL;
+	intf = xencons->intf;
 
 	cons = intf->in_cons;
 	prod = intf->in_prod;
@@ -129,7 +157,7 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
 	mb();			/* read ring before consuming */
 	intf->in_cons = cons;
 
-	notify_daemon();
+	notify_daemon(xencons);
 	return recv;
 }
 
@@ -172,78 +200,359 @@ static int xen_hvm_console_init(void)
 	int r;
 	uint64_t v = 0;
 	unsigned long mfn;
+	struct xencons_info *info;
 
 	if (!xen_hvm_domain())
 		return -ENODEV;
 
-	if (xencons_if != NULL)
-		return -EBUSY;
+	info = vtermno_to_xencons(HVC_COOKIE);
+	if (!info) {
+		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
+		if (!info)
+			return -ENOMEM;
+	}
+
+	/* already configured */
+	if (info->intf != NULL)
+		return 0;
 
 	r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
-	if (r < 0)
+	if (r < 0) {
+		kfree(info);
 		return -ENODEV;
-	console_evtchn = v;
+	}
+	info->evtchn = v;
 	hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
-	if (r < 0)
+	if (r < 0) {
+		kfree(info);
 		return -ENODEV;
+	}
 	mfn = v;
-	xencons_if = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
-	if (xencons_if == NULL)
+	info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
+	if (info->intf == NULL) {
+		kfree(info);
+		return -ENODEV;
+	}
+	info->vtermno = HVC_COOKIE;
+
+	spin_lock(&xencons_lock);
+	list_add_tail(&info->list, &xenconsoles);
+	spin_unlock(&xencons_lock);
+
+	return 0;
+}
+
+static int xen_pv_console_init(void)
+{
+	struct xencons_info *info;
+
+	if (!xen_pv_domain())
+		return -ENODEV;
+
+	if (!xen_start_info->console.domU.evtchn)
+		return -ENODEV;
+
+	info = vtermno_to_xencons(HVC_COOKIE);
+	if (!info) {
+		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
+		if (!info)
+			return -ENOMEM;
+	}
+
+	/* already configured */
+	if (info->intf != NULL)
+		return 0;
+
+	info->evtchn = xen_start_info->console.domU.evtchn;
+	info->intf = mfn_to_virt(xen_start_info->console.domU.mfn);
+	info->vtermno = HVC_COOKIE;
+
+	spin_lock(&xencons_lock);
+	list_add_tail(&info->list, &xenconsoles);
+	spin_unlock(&xencons_lock);
+
+	return 0;
+}
+
+static int xen_initial_domain_console_init(void)
+{
+	struct xencons_info *info;
+
+	if (!xen_initial_domain())
 		return -ENODEV;
 
+	info = vtermno_to_xencons(HVC_COOKIE);
+	if (!info) {
+		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
+		if (!info)
+			return -ENOMEM;
+	}
+
+	info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
+	info->vtermno = HVC_COOKIE;
+
+	spin_lock(&xencons_lock);
+	list_add_tail(&info->list, &xenconsoles);
+	spin_unlock(&xencons_lock);
+
 	return 0;
 }
 
 static int __init xen_hvc_init(void)
 {
-	struct hvc_struct *hp;
-	struct hv_ops *ops;
 	int r;
+	struct xencons_info *info;
+	const struct hv_ops *ops;
 
 	if (!xen_domain())
 		return -ENODEV;
 
 	if (xen_initial_domain()) {
 		ops = &dom0_hvc_ops;
-		xencons_irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
+		r = xen_initial_domain_console_init();
+		if (r < 0)
+			return r;
+		info = vtermno_to_xencons(HVC_COOKIE);
 	} else {
 		ops = &domU_hvc_ops;
-		if (xen_pv_domain()) {
-			if (!xen_start_info->console.domU.evtchn)
-				return -ENODEV;
-			console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
-			console_evtchn = xen_start_info->console.domU.evtchn;
-		} else {
+		if (xen_hvm_domain())
 			r = xen_hvm_console_init();
-			if (r < 0)
-				return r;
-		}
-		xencons_irq = bind_evtchn_to_irq(console_evtchn);
-		if (xencons_irq < 0)
-			xencons_irq = 0; /* NO_IRQ */
 		else
-			irq_set_noprobe(xencons_irq);
+			r = xen_pv_console_init();
+		if (r < 0)
+			return r;
+
+		info = vtermno_to_xencons(HVC_COOKIE);
+		info->irq = bind_evtchn_to_irq(info->evtchn);
+	}
+	if (info->irq < 0)
+		info->irq = 0; /* NO_IRQ */
+	else
+		irq_set_noprobe(info->irq);
+
+	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
+	if (IS_ERR(info->hvc)) {
+		r = PTR_ERR(info->hvc);
+		spin_lock(&xencons_lock);
+		list_del(&info->list);
+		spin_unlock(&xencons_lock);
+		if (info->irq)
+			unbind_from_irqhandler(info->irq, NULL);
+		kfree(info);
+		return r;
 	}
 
-	hp = hvc_alloc(HVC_COOKIE, xencons_irq, ops, 256);
-	if (IS_ERR(hp))
-		return PTR_ERR(hp);
+	return xenbus_register_frontend(&xencons_driver);
+}
 
-	hvc = hp;
+void xen_console_resume(void)
+{
+	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
+	if (info != NULL && info->irq)
+		rebind_evtchn_irq(info->evtchn, info->irq);
+}
+
+static void xencons_disconnect_backend(struct xencons_info *info)
+{
+	if (info->irq > 0)
+		unbind_from_irqhandler(info->irq, NULL);
+	info->irq = 0;
+	if (info->evtchn > 0)
+		xenbus_free_evtchn(info->xbdev, info->evtchn);
+	info->evtchn = 0;
+	if (info->gntref > 0)
+		gnttab_free_grant_references(info->gntref);
+	info->gntref = 0;
+	if (info->hvc != NULL)
+		hvc_remove(info->hvc);
+	info->hvc = NULL;
+}
 
+static void xencons_free(struct xencons_info *info)
+{
+	free_page((unsigned long)info->intf);
+	info->intf = NULL;
+	info->vtermno = 0;
+	kfree(info);
+}
+
+static int xen_console_remove(struct xencons_info *info)
+{
+	xencons_disconnect_backend(info);
+	spin_lock(&xencons_lock);
+	list_del(&info->list);
+	spin_unlock(&xencons_lock);
+	if (info->xbdev != NULL)
+		xencons_free(info);
+	else {
+		if (xen_hvm_domain())
+			iounmap(info->intf);
+		kfree(info);
+	}
 	return 0;
 }
 
-void xen_console_resume(void)
+static int xencons_remove(struct xenbus_device *dev)
+{
+	return xen_console_remove(dev_get_drvdata(&dev->dev));
+}
+
+static int xencons_connect_backend(struct xenbus_device *dev,
+				  struct xencons_info *info)
+{
+	int ret, evtchn, devid, ref, irq;
+	struct xenbus_transaction xbt;
+	grant_ref_t gref_head;
+	unsigned long mfn;
+
+	ret = xenbus_alloc_evtchn(dev, &evtchn);
+	if (ret)
+		return ret;
+	info->evtchn = evtchn;
+	irq = bind_evtchn_to_irq(evtchn);
+	if (irq < 0)
+		return irq;
+	info->irq = irq;
+	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
+	info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
+			irq, &domU_hvc_ops, 256);
+	if (IS_ERR(info->hvc))
+		return PTR_ERR(info->hvc);
+	if (xen_pv_domain())
+		mfn = virt_to_mfn(info->intf);
+	else
+		mfn = __pa(info->intf) >> PAGE_SHIFT;
+	ret = gnttab_alloc_grant_references(1, &gref_head);
+	if (ret < 0)
+		return ret;
+	info->gntref = gref_head;
+	ref = gnttab_claim_grant_reference(&gref_head);
+	if (ref < 0)
+		return ref;
+	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
+			mfn, 0);
+
+ again:
+	ret = xenbus_transaction_start(&xbt);
+	if (ret) {
+		xenbus_dev_fatal(dev, ret, "starting transaction");
+		return ret;
+	}
+	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
+	if (ret)
+		goto error_xenbus;
+	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
+			    evtchn);
+	if (ret)
+		goto error_xenbus;
+	ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
+	if (ret)
+		goto error_xenbus;
+	ret = xenbus_transaction_end(xbt, 0);
+	if (ret) {
+		if (ret == -EAGAIN)
+			goto again;
+		xenbus_dev_fatal(dev, ret, "completing transaction");
+		return ret;
+	}
+
+	xenbus_switch_state(dev, XenbusStateInitialised);
+	return 0;
+
+ error_xenbus:
+	xenbus_transaction_end(xbt, 1);
+	xenbus_dev_fatal(dev, ret, "writing xenstore");
+	return ret;
+}
+
+static int __devinit xencons_probe(struct xenbus_device *dev,
+				  const struct xenbus_device_id *id)
+{
+	int ret, devid;
+	struct xencons_info *info;
+
+	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
+	if (devid == 0)
+		return -ENODEV;
+
+	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
+	if (!info)
+		goto error_nomem;
+	dev_set_drvdata(&dev->dev, info);
+	info->xbdev = dev;
+	info->vtermno = xenbus_devid_to_vtermno(devid);
+	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	if (!info->intf)
+		goto error_nomem;
+
+	ret = xencons_connect_backend(dev, info);
+	if (ret < 0)
+		goto error;
+	spin_lock(&xencons_lock);
+	list_add_tail(&info->list, &xenconsoles);
+	spin_unlock(&xencons_lock);
+
+	return 0;
+
+ error_nomem:
+	ret = -ENOMEM;
+	xenbus_dev_fatal(dev, ret, "allocating device memory");
+ error:
+	xencons_disconnect_backend(info);
+	xencons_free(info);
+	return ret;
+}
+
+static int xencons_resume(struct xenbus_device *dev)
 {
-	if (xencons_irq)
-		rebind_evtchn_irq(console_evtchn, xencons_irq);
+	struct xencons_info *info = dev_get_drvdata(&dev->dev);
+
+	xencons_disconnect_backend(info);
+	memset(info->intf, 0, PAGE_SIZE);
+	return xencons_connect_backend(dev, info);
 }
 
+static void xencons_backend_changed(struct xenbus_device *dev,
+				   enum xenbus_state backend_state)
+{
+	switch (backend_state) {
+	case XenbusStateReconfiguring:
+	case XenbusStateReconfigured:
+	case XenbusStateInitialising:
+	case XenbusStateInitialised:
+	case XenbusStateUnknown:
+	case XenbusStateClosed:
+		break;
+
+	case XenbusStateInitWait:
+		break;
+
+	case XenbusStateConnected:
+		xenbus_switch_state(dev, XenbusStateConnected);
+		break;
+
+	case XenbusStateClosing:
+		xenbus_frontend_closed(dev);
+		break;
+	}
+}
+
+static const struct xenbus_device_id xencons_ids[] = {
+	{ "console" },
+	{ "" }
+};
+
+
 static void __exit xen_hvc_fini(void)
 {
-	if (hvc)
-		hvc_remove(hvc);
+	struct xencons_info *entry, *next;
+
+	if (list_empty(&xenconsoles))
+			return;
+
+	list_for_each_entry_safe(entry, next, &xenconsoles, list) {
+		xen_console_remove(entry);
+	}
 }
 
 static int xen_cons_init(void)
@@ -256,18 +565,28 @@ static int xen_cons_init(void)
 	if (xen_initial_domain())
 		ops = &dom0_hvc_ops;
 	else {
+		int r;
 		ops = &domU_hvc_ops;
 
-		if (xen_pv_domain())
-			console_evtchn = xen_start_info->console.domU.evtchn;
+		if (xen_hvm_domain())
+			r = xen_hvm_console_init();
 		else
-			xen_hvm_console_init();
+			r = xen_pv_console_init();
+		if (r < 0)
+			return r;
 	}
 
 	hvc_instantiate(HVC_COOKIE, 0, ops);
 	return 0;
 }
 
+static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
+	.probe = xencons_probe,
+	.remove = xencons_remove,
+	.resume = xencons_resume,
+	.otherend_changed = xencons_backend_changed,
+);
+
 module_init(xen_hvc_init);
 module_exit(xen_hvc_fini);
 console_initcall(xen_cons_init);
-- 
1.7.2.5

Re: [Xen-devel] [PATCH v3] hvc_xen: implement multiconsole support

[Konrad Rzeszutek Wilk]

On Mon, Jan 30, 2012 at 04:02:31PM +0000, Stefano Stabellini wrote:
> This patch implements support for multiple consoles:
> consoles other than the first one are setup using the traditional xenbus
> and grant-table based mechanism.
> We use a list to keep track of the allocated consoles, we don't
> expect too many of them anyway.
> 

So looks good. applied to #testing. How do I test "multiple" consoles?

> 
> Changes in v3:
> 
> - call hvc_remove before removing the console from xenconsoles;
> - do not lock xencons_lock twice in the destruction path;
> - use the DEFINE_XENBUS_DRIVER macro.
> 
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
>  drivers/tty/hvc/hvc_xen.c |  435 +++++++++++++++++++++++++++++++++++++++------
>  1 files changed, 377 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
> index d5000aa..26090c7 100644
> --- a/drivers/tty/hvc/hvc_xen.c
> +++ b/drivers/tty/hvc/hvc_xen.c
> @@ -23,6 +23,7 @@
>  #include <linux/err.h>
>  #include <linux/init.h>
>  #include <linux/types.h>
> +#include <linux/list.h>
>  
>  #include <asm/io.h>
>  #include <asm/xen/hypervisor.h>
> @@ -30,47 +31,67 @@
>  #include <xen/xen.h>
>  #include <xen/interface/xen.h>
>  #include <xen/hvm.h>
> +#include <xen/grant_table.h>
>  #include <xen/page.h>
>  #include <xen/events.h>
>  #include <xen/interface/io/console.h>
>  #include <xen/hvc-console.h>
> +#include <xen/xenbus.h>
>  
>  #include "hvc_console.h"
>  
>  #define HVC_COOKIE   0x58656e /* "Xen" in hex */
>  
> -static struct hvc_struct *hvc;
> -static int xencons_irq;
> +struct xencons_info {
> +	struct list_head list;
> +	struct xenbus_device *xbdev;
> +	struct xencons_interface *intf;
> +	unsigned int evtchn;
> +	struct hvc_struct *hvc;
> +	int irq;
> +	int vtermno;
> +	grant_ref_t gntref;
> +};
> +
> +static LIST_HEAD(xenconsoles);
> +static DEFINE_SPINLOCK(xencons_lock);
> +static struct xenbus_driver xencons_driver;
>  
>  /* ------------------------------------------------------------------ */
>  
> -static unsigned long console_pfn = ~0ul;
> -static unsigned int console_evtchn = ~0ul;
> -static struct xencons_interface *xencons_if = NULL;
> +static struct xencons_info *vtermno_to_xencons(int vtermno)
> +{
> +	struct xencons_info *entry, *n, *ret = NULL;
> +
> +	if (list_empty(&xenconsoles))
> +			return NULL;
>  
> -static inline struct xencons_interface *xencons_interface(void)
> +	list_for_each_entry_safe(entry, n, &xenconsoles, list) {
> +		if (entry->vtermno == vtermno) {
> +			ret  = entry;
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static inline int xenbus_devid_to_vtermno(int devid)
>  {
> -	if (xencons_if != NULL)
> -		return xencons_if;
> -	if (console_pfn == ~0ul)
> -		return mfn_to_virt(xen_start_info->console.domU.mfn);
> -	else
> -		return __va(console_pfn << PAGE_SHIFT);
> +	return devid + HVC_COOKIE;
>  }
>  
> -static inline void notify_daemon(void)
> +static inline void notify_daemon(struct xencons_info *cons)
>  {
>  	/* Use evtchn: this is called early, before irq is set up. */
> -	if (console_evtchn == ~0ul)
> -		notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
> -	else
> -		notify_remote_via_evtchn(console_evtchn);
> +	notify_remote_via_evtchn(cons->evtchn);
>  }
>  
> -static int __write_console(const char *data, int len)
> +static int __write_console(struct xencons_info *xencons,
> +		const char *data, int len)
>  {
> -	struct xencons_interface *intf = xencons_interface();
>  	XENCONS_RING_IDX cons, prod;
> +	struct xencons_interface *intf = xencons->intf;
>  	int sent = 0;
>  
>  	cons = intf->out_cons;
> @@ -85,13 +106,16 @@ static int __write_console(const char *data, int len)
>  	intf->out_prod = prod;
>  
>  	if (sent)
> -		notify_daemon();
> +		notify_daemon(xencons);
>  	return sent;
>  }
>  
>  static int domU_write_console(uint32_t vtermno, const char *data, int len)
>  {
>  	int ret = len;
> +	struct xencons_info *cons = vtermno_to_xencons(vtermno);
> +	if (cons == NULL)
> +		return -EINVAL;
>  
>  	/*
>  	 * Make sure the whole buffer is emitted, polling if
> @@ -100,7 +124,7 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
>  	 * kernel is crippled.
>  	 */
>  	while (len) {
> -		int sent = __write_console(data, len);
> +		int sent = __write_console(cons, data, len);
>  		
>  		data += sent;
>  		len -= sent;
> @@ -114,9 +138,13 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
>  
>  static int domU_read_console(uint32_t vtermno, char *buf, int len)
>  {
> -	struct xencons_interface *intf = xencons_interface();
> +	struct xencons_interface *intf;
>  	XENCONS_RING_IDX cons, prod;
>  	int recv = 0;
> +	struct xencons_info *xencons = vtermno_to_xencons(vtermno);
> +	if (xencons == NULL)
> +		return -EINVAL;
> +	intf = xencons->intf;
>  
>  	cons = intf->in_cons;
>  	prod = intf->in_prod;
> @@ -129,7 +157,7 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
>  	mb();			/* read ring before consuming */
>  	intf->in_cons = cons;
>  
> -	notify_daemon();
> +	notify_daemon(xencons);
>  	return recv;
>  }
>  
> @@ -172,78 +200,359 @@ static int xen_hvm_console_init(void)
>  	int r;
>  	uint64_t v = 0;
>  	unsigned long mfn;
> +	struct xencons_info *info;
>  
>  	if (!xen_hvm_domain())
>  		return -ENODEV;
>  
> -	if (xencons_if != NULL)
> -		return -EBUSY;
> +	info = vtermno_to_xencons(HVC_COOKIE);
> +	if (!info) {
> +		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
> +		if (!info)
> +			return -ENOMEM;
> +	}
> +
> +	/* already configured */
> +	if (info->intf != NULL)
> +		return 0;
>  
>  	r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
> -	if (r < 0)
> +	if (r < 0) {
> +		kfree(info);
>  		return -ENODEV;
> -	console_evtchn = v;
> +	}
> +	info->evtchn = v;
>  	hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
> -	if (r < 0)
> +	if (r < 0) {
> +		kfree(info);
>  		return -ENODEV;
> +	}
>  	mfn = v;
> -	xencons_if = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
> -	if (xencons_if == NULL)
> +	info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
> +	if (info->intf == NULL) {
> +		kfree(info);
> +		return -ENODEV;
> +	}
> +	info->vtermno = HVC_COOKIE;
> +
> +	spin_lock(&xencons_lock);
> +	list_add_tail(&info->list, &xenconsoles);
> +	spin_unlock(&xencons_lock);
> +
> +	return 0;
> +}
> +
> +static int xen_pv_console_init(void)
> +{
> +	struct xencons_info *info;
> +
> +	if (!xen_pv_domain())
> +		return -ENODEV;
> +
> +	if (!xen_start_info->console.domU.evtchn)
> +		return -ENODEV;
> +
> +	info = vtermno_to_xencons(HVC_COOKIE);
> +	if (!info) {
> +		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
> +		if (!info)
> +			return -ENOMEM;
> +	}
> +
> +	/* already configured */
> +	if (info->intf != NULL)
> +		return 0;
> +
> +	info->evtchn = xen_start_info->console.domU.evtchn;
> +	info->intf = mfn_to_virt(xen_start_info->console.domU.mfn);
> +	info->vtermno = HVC_COOKIE;
> +
> +	spin_lock(&xencons_lock);
> +	list_add_tail(&info->list, &xenconsoles);
> +	spin_unlock(&xencons_lock);
> +
> +	return 0;
> +}
> +
> +static int xen_initial_domain_console_init(void)
> +{
> +	struct xencons_info *info;
> +
> +	if (!xen_initial_domain())
>  		return -ENODEV;
>  
> +	info = vtermno_to_xencons(HVC_COOKIE);
> +	if (!info) {
> +		info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
> +		if (!info)
> +			return -ENOMEM;
> +	}
> +
> +	info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
> +	info->vtermno = HVC_COOKIE;
> +
> +	spin_lock(&xencons_lock);
> +	list_add_tail(&info->list, &xenconsoles);
> +	spin_unlock(&xencons_lock);
> +
>  	return 0;
>  }
>  
>  static int __init xen_hvc_init(void)
>  {
> -	struct hvc_struct *hp;
> -	struct hv_ops *ops;
>  	int r;
> +	struct xencons_info *info;
> +	const struct hv_ops *ops;
>  
>  	if (!xen_domain())
>  		return -ENODEV;
>  
>  	if (xen_initial_domain()) {
>  		ops = &dom0_hvc_ops;
> -		xencons_irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
> +		r = xen_initial_domain_console_init();
> +		if (r < 0)
> +			return r;
> +		info = vtermno_to_xencons(HVC_COOKIE);
>  	} else {
>  		ops = &domU_hvc_ops;
> -		if (xen_pv_domain()) {
> -			if (!xen_start_info->console.domU.evtchn)
> -				return -ENODEV;
> -			console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
> -			console_evtchn = xen_start_info->console.domU.evtchn;
> -		} else {
> +		if (xen_hvm_domain())
>  			r = xen_hvm_console_init();
> -			if (r < 0)
> -				return r;
> -		}
> -		xencons_irq = bind_evtchn_to_irq(console_evtchn);
> -		if (xencons_irq < 0)
> -			xencons_irq = 0; /* NO_IRQ */
>  		else
> -			irq_set_noprobe(xencons_irq);
> +			r = xen_pv_console_init();
> +		if (r < 0)
> +			return r;
> +
> +		info = vtermno_to_xencons(HVC_COOKIE);
> +		info->irq = bind_evtchn_to_irq(info->evtchn);
> +	}
> +	if (info->irq < 0)
> +		info->irq = 0; /* NO_IRQ */
> +	else
> +		irq_set_noprobe(info->irq);
> +
> +	info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
> +	if (IS_ERR(info->hvc)) {
> +		r = PTR_ERR(info->hvc);
> +		spin_lock(&xencons_lock);
> +		list_del(&info->list);
> +		spin_unlock(&xencons_lock);
> +		if (info->irq)
> +			unbind_from_irqhandler(info->irq, NULL);
> +		kfree(info);
> +		return r;
>  	}
>  
> -	hp = hvc_alloc(HVC_COOKIE, xencons_irq, ops, 256);
> -	if (IS_ERR(hp))
> -		return PTR_ERR(hp);
> +	return xenbus_register_frontend(&xencons_driver);
> +}
>  
> -	hvc = hp;
> +void xen_console_resume(void)
> +{
> +	struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
> +	if (info != NULL && info->irq)
> +		rebind_evtchn_irq(info->evtchn, info->irq);
> +}
> +
> +static void xencons_disconnect_backend(struct xencons_info *info)
> +{
> +	if (info->irq > 0)
> +		unbind_from_irqhandler(info->irq, NULL);
> +	info->irq = 0;
> +	if (info->evtchn > 0)
> +		xenbus_free_evtchn(info->xbdev, info->evtchn);
> +	info->evtchn = 0;
> +	if (info->gntref > 0)
> +		gnttab_free_grant_references(info->gntref);
> +	info->gntref = 0;
> +	if (info->hvc != NULL)
> +		hvc_remove(info->hvc);
> +	info->hvc = NULL;
> +}
>  
> +static void xencons_free(struct xencons_info *info)
> +{
> +	free_page((unsigned long)info->intf);
> +	info->intf = NULL;
> +	info->vtermno = 0;
> +	kfree(info);
> +}
> +
> +static int xen_console_remove(struct xencons_info *info)
> +{
> +	xencons_disconnect_backend(info);
> +	spin_lock(&xencons_lock);
> +	list_del(&info->list);
> +	spin_unlock(&xencons_lock);
> +	if (info->xbdev != NULL)
> +		xencons_free(info);
> +	else {
> +		if (xen_hvm_domain())
> +			iounmap(info->intf);
> +		kfree(info);
> +	}
>  	return 0;
>  }
>  
> -void xen_console_resume(void)
> +static int xencons_remove(struct xenbus_device *dev)
> +{
> +	return xen_console_remove(dev_get_drvdata(&dev->dev));
> +}
> +
> +static int xencons_connect_backend(struct xenbus_device *dev,
> +				  struct xencons_info *info)
> +{
> +	int ret, evtchn, devid, ref, irq;
> +	struct xenbus_transaction xbt;
> +	grant_ref_t gref_head;
> +	unsigned long mfn;
> +
> +	ret = xenbus_alloc_evtchn(dev, &evtchn);
> +	if (ret)
> +		return ret;
> +	info->evtchn = evtchn;
> +	irq = bind_evtchn_to_irq(evtchn);
> +	if (irq < 0)
> +		return irq;
> +	info->irq = irq;
> +	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
> +	info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
> +			irq, &domU_hvc_ops, 256);
> +	if (IS_ERR(info->hvc))
> +		return PTR_ERR(info->hvc);
> +	if (xen_pv_domain())
> +		mfn = virt_to_mfn(info->intf);
> +	else
> +		mfn = __pa(info->intf) >> PAGE_SHIFT;
> +	ret = gnttab_alloc_grant_references(1, &gref_head);
> +	if (ret < 0)
> +		return ret;
> +	info->gntref = gref_head;
> +	ref = gnttab_claim_grant_reference(&gref_head);
> +	if (ref < 0)
> +		return ref;
> +	gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
> +			mfn, 0);
> +
> + again:
> +	ret = xenbus_transaction_start(&xbt);
> +	if (ret) {
> +		xenbus_dev_fatal(dev, ret, "starting transaction");
> +		return ret;
> +	}
> +	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
> +	if (ret)
> +		goto error_xenbus;
> +	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
> +			    evtchn);
> +	if (ret)
> +		goto error_xenbus;
> +	ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
> +	if (ret)
> +		goto error_xenbus;
> +	ret = xenbus_transaction_end(xbt, 0);
> +	if (ret) {
> +		if (ret == -EAGAIN)
> +			goto again;
> +		xenbus_dev_fatal(dev, ret, "completing transaction");
> +		return ret;
> +	}
> +
> +	xenbus_switch_state(dev, XenbusStateInitialised);
> +	return 0;
> +
> + error_xenbus:
> +	xenbus_transaction_end(xbt, 1);
> +	xenbus_dev_fatal(dev, ret, "writing xenstore");
> +	return ret;
> +}
> +
> +static int __devinit xencons_probe(struct xenbus_device *dev,
> +				  const struct xenbus_device_id *id)
> +{
> +	int ret, devid;
> +	struct xencons_info *info;
> +
> +	devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
> +	if (devid == 0)
> +		return -ENODEV;
> +
> +	info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
> +	if (!info)
> +		goto error_nomem;
> +	dev_set_drvdata(&dev->dev, info);
> +	info->xbdev = dev;
> +	info->vtermno = xenbus_devid_to_vtermno(devid);
> +	info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
> +	if (!info->intf)
> +		goto error_nomem;
> +
> +	ret = xencons_connect_backend(dev, info);
> +	if (ret < 0)
> +		goto error;
> +	spin_lock(&xencons_lock);
> +	list_add_tail(&info->list, &xenconsoles);
> +	spin_unlock(&xencons_lock);
> +
> +	return 0;
> +
> + error_nomem:
> +	ret = -ENOMEM;
> +	xenbus_dev_fatal(dev, ret, "allocating device memory");
> + error:
> +	xencons_disconnect_backend(info);
> +	xencons_free(info);
> +	return ret;
> +}
> +
> +static int xencons_resume(struct xenbus_device *dev)
>  {
> -	if (xencons_irq)
> -		rebind_evtchn_irq(console_evtchn, xencons_irq);
> +	struct xencons_info *info = dev_get_drvdata(&dev->dev);
> +
> +	xencons_disconnect_backend(info);
> +	memset(info->intf, 0, PAGE_SIZE);
> +	return xencons_connect_backend(dev, info);
>  }
>  
> +static void xencons_backend_changed(struct xenbus_device *dev,
> +				   enum xenbus_state backend_state)
> +{
> +	switch (backend_state) {
> +	case XenbusStateReconfiguring:
> +	case XenbusStateReconfigured:
> +	case XenbusStateInitialising:
> +	case XenbusStateInitialised:
> +	case XenbusStateUnknown:
> +	case XenbusStateClosed:
> +		break;
> +
> +	case XenbusStateInitWait:
> +		break;
> +
> +	case XenbusStateConnected:
> +		xenbus_switch_state(dev, XenbusStateConnected);
> +		break;
> +
> +	case XenbusStateClosing:
> +		xenbus_frontend_closed(dev);
> +		break;
> +	}
> +}
> +
> +static const struct xenbus_device_id xencons_ids[] = {
> +	{ "console" },
> +	{ "" }
> +};
> +
> +
>  static void __exit xen_hvc_fini(void)
>  {
> -	if (hvc)
> -		hvc_remove(hvc);
> +	struct xencons_info *entry, *next;
> +
> +	if (list_empty(&xenconsoles))
> +			return;
> +
> +	list_for_each_entry_safe(entry, next, &xenconsoles, list) {
> +		xen_console_remove(entry);
> +	}
>  }
>  
>  static int xen_cons_init(void)
> @@ -256,18 +565,28 @@ static int xen_cons_init(void)
>  	if (xen_initial_domain())
>  		ops = &dom0_hvc_ops;
>  	else {
> +		int r;
>  		ops = &domU_hvc_ops;
>  
> -		if (xen_pv_domain())
> -			console_evtchn = xen_start_info->console.domU.evtchn;
> +		if (xen_hvm_domain())
> +			r = xen_hvm_console_init();
>  		else
> -			xen_hvm_console_init();
> +			r = xen_pv_console_init();
> +		if (r < 0)
> +			return r;
>  	}
>  
>  	hvc_instantiate(HVC_COOKIE, 0, ops);
>  	return 0;
>  }
>  
> +static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
> +	.probe = xencons_probe,
> +	.remove = xencons_remove,
> +	.resume = xencons_resume,
> +	.otherend_changed = xencons_backend_changed,
> +);
> +
>  module_init(xen_hvc_init);
>  module_exit(xen_hvc_fini);
>  console_initcall(xen_cons_init);
> -- 
> 1.7.2.5
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Re: [Xen-devel] [PATCH v3] hvc_xen: implement multiconsole support

[Stefano Stabellini]

On Wed, 1 Feb 2012, Konrad Rzeszutek Wilk wrote:
> On Mon, Jan 30, 2012 at 04:02:31PM +0000, Stefano Stabellini wrote:
> > This patch implements support for multiple consoles:
> > consoles other than the first one are setup using the traditional xenbus
> > and grant-table based mechanism.
> > We use a list to keep track of the allocated consoles, we don't
> > expect too many of them anyway.
> >
> 
> So looks good. applied to #testing. How do I test "multiple" consoles?

Interesting question :)

First of all testing a pv console alongside an emulated serial is easy:
by default xl creates a pv console for all hvm guests. So you just need
to start using it (something like console=ttyS0 console=hvc0 on a PV on
HVM guest).
You can connect to the pv console with the following command:

xl console -t pv <domain_name>


Then, in order to test multiple pv consoles, you need the toolstack to
create more than one for you (see appended patch that creates 2 pv
consoles for PV on HVM guests). If you create two pv consoles, you can
connect to the second one with the following command:

xl console -t pv -n 1 <domain_name>

BTW in the patch below I am seeting QEMU as console backend because it
is the only one that can handle multiple pv consoles.


8<----

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index e1c615f..ec2c362 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -554,14 +554,21 @@ static int do_domain_create(libxl__gc *gc, libxl_domain_config *d_config,
     switch (d_config->c_info.type) {
     case LIBXL_DOMAIN_TYPE_HVM:
     {
-        libxl_device_console console;
+        libxl_device_console console, console2;
         libxl_device_vkb vkb;
 
         ret = init_console_info(&console, 0);
         if ( ret )
             goto error_out;
+        console.consback = LIBXL_CONSOLE_BACKEND_IOEMU;
         libxl__device_console_add(gc, domid, &console, &state);
         libxl_device_console_dispose(&console);
+        ret = init_console_info(&console2, 1);
+        if ( ret )
+            goto error_out;
+        console2.consback = LIBXL_CONSOLE_BACKEND_IOEMU;
+        libxl__device_console_add(gc, domid, &console2, NULL);
+        libxl_device_console_dispose(&console2);
 
         ret = libxl_device_vkb_init(ctx, &vkb);
         if ( ret )