Date:	Tue, 31 Jan 2012 21:13:18 -0400
From:	Konrad Rzeszutek Wilk <konrad@...nok.org>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc:	xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org,
	konrad.wilk@...cle.com
Subject: Re: [Xen-devel] [PATCH v3] hvc_xen: implement multiconsole support

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@...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@...ts.xensource.com
> http://lists.xensource.com/xen-devel
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