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Subject[PATCH v3] hvc_xen: implement multiconsole support
Date
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


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