diff options
Diffstat (limited to 'drivers/tty/hvc/hvc_xen.c')
| -rw-r--r-- | drivers/tty/hvc/hvc_xen.c | 771 |
1 files changed, 771 insertions, 0 deletions
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c new file mode 100644 index 000000000..281bc83ac --- /dev/null +++ b/drivers/tty/hvc/hvc_xen.c @@ -0,0 +1,771 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * xen console driver interface to hvc_console.c + * + * (c) 2007 Gerd Hoffmann <kraxel@suse.de> + */ + +#include <linux/console.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/irq.h> +#include <linux/init.h> +#include <linux/types.h> +#include <linux/list.h> +#include <linux/serial_core.h> + +#include <asm/io.h> +#include <asm/xen/hypervisor.h> + +#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/interface/sched.h> +#include <xen/hvc-console.h> +#include <xen/xenbus.h> + +#include "hvc_console.h" + +#define HVC_COOKIE 0x58656e /* "Xen" in hex */ + +struct xencons_info { + struct list_head list; + struct xenbus_device *xbdev; + struct xencons_interface *intf; + unsigned int evtchn; + XENCONS_RING_IDX out_cons; + unsigned int out_cons_same; + struct hvc_struct *hvc; + int irq; + int vtermno; + grant_ref_t gntref; + spinlock_t ring_lock; +}; + +static LIST_HEAD(xenconsoles); +static DEFINE_SPINLOCK(xencons_lock); + +/* ------------------------------------------------------------------ */ + +static struct xencons_info *vtermno_to_xencons(int vtermno) +{ + struct xencons_info *entry, *ret = NULL; + unsigned long flags; + + spin_lock_irqsave(&xencons_lock, flags); + if (list_empty(&xenconsoles)) { + spin_unlock_irqrestore(&xencons_lock, flags); + return NULL; + } + + list_for_each_entry(entry, &xenconsoles, list) { + if (entry->vtermno == vtermno) { + ret = entry; + break; + } + } + spin_unlock_irqrestore(&xencons_lock, flags); + + return ret; +} + +static inline int xenbus_devid_to_vtermno(int devid) +{ + return devid + HVC_COOKIE; +} + +static inline void notify_daemon(struct xencons_info *cons) +{ + /* Use evtchn: this is called early, before irq is set up. */ + notify_remote_via_evtchn(cons->evtchn); +} + +static int __write_console(struct xencons_info *xencons, + const char *data, int len) +{ + XENCONS_RING_IDX cons, prod; + struct xencons_interface *intf = xencons->intf; + int sent = 0; + unsigned long flags; + + spin_lock_irqsave(&xencons->ring_lock, flags); + cons = intf->out_cons; + prod = intf->out_prod; + mb(); /* update queue values before going on */ + + if ((prod - cons) > sizeof(intf->out)) { + spin_unlock_irqrestore(&xencons->ring_lock, flags); + pr_err_once("xencons: Illegal ring page indices"); + return -EINVAL; + } + + while ((sent < len) && ((prod - cons) < sizeof(intf->out))) + intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++]; + + wmb(); /* write ring before updating pointer */ + intf->out_prod = prod; + spin_unlock_irqrestore(&xencons->ring_lock, flags); + + if (sent) + 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 + * necessary. We don't ever want to rely on the hvc daemon + * because the most interesting console output is when the + * kernel is crippled. + */ + while (len) { + int sent = __write_console(cons, data, len); + + if (sent < 0) + return sent; + + data += sent; + len -= sent; + + if (unlikely(len)) + HYPERVISOR_sched_op(SCHEDOP_yield, NULL); + } + + return ret; +} + +static int domU_read_console(uint32_t vtermno, char *buf, int len) +{ + struct xencons_interface *intf; + XENCONS_RING_IDX cons, prod; + int recv = 0; + struct xencons_info *xencons = vtermno_to_xencons(vtermno); + unsigned int eoiflag = 0; + unsigned long flags; + + if (xencons == NULL) + return -EINVAL; + intf = xencons->intf; + + spin_lock_irqsave(&xencons->ring_lock, flags); + cons = intf->in_cons; + prod = intf->in_prod; + mb(); /* get pointers before reading ring */ + + if ((prod - cons) > sizeof(intf->in)) { + spin_unlock_irqrestore(&xencons->ring_lock, flags); + pr_err_once("xencons: Illegal ring page indices"); + return -EINVAL; + } + + while (cons != prod && recv < len) + buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)]; + + mb(); /* read ring before consuming */ + intf->in_cons = cons; + + /* + * When to mark interrupt having been spurious: + * - there was no new data to be read, and + * - the backend did not consume some output bytes, and + * - the previous round with no read data didn't see consumed bytes + * (we might have a race with an interrupt being in flight while + * updating xencons->out_cons, so account for that by allowing one + * round without any visible reason) + */ + if (intf->out_cons != xencons->out_cons) { + xencons->out_cons = intf->out_cons; + xencons->out_cons_same = 0; + } + if (!recv && xencons->out_cons_same++ > 1) { + eoiflag = XEN_EOI_FLAG_SPURIOUS; + } + spin_unlock_irqrestore(&xencons->ring_lock, flags); + + if (recv) { + notify_daemon(xencons); + } + + xen_irq_lateeoi(xencons->irq, eoiflag); + + return recv; +} + +static const struct hv_ops domU_hvc_ops = { + .get_chars = domU_read_console, + .put_chars = domU_write_console, + .notifier_add = notifier_add_irq, + .notifier_del = notifier_del_irq, + .notifier_hangup = notifier_hangup_irq, +}; + +static int dom0_read_console(uint32_t vtermno, char *buf, int len) +{ + return HYPERVISOR_console_io(CONSOLEIO_read, len, buf); +} + +/* + * Either for a dom0 to write to the system console, or a domU with a + * debug version of Xen + */ +static int dom0_write_console(uint32_t vtermno, const char *str, int len) +{ + int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str); + if (rc < 0) + return rc; + + return len; +} + +static const struct hv_ops dom0_hvc_ops = { + .get_chars = dom0_read_console, + .put_chars = dom0_write_console, + .notifier_add = notifier_add_irq, + .notifier_del = notifier_del_irq, + .notifier_hangup = notifier_hangup_irq, +}; + +static int xen_hvm_console_init(void) +{ + int r; + uint64_t v = 0; + unsigned long gfn, flags; + struct xencons_info *info; + + if (!xen_hvm_domain()) + return -ENODEV; + + info = vtermno_to_xencons(HVC_COOKIE); + if (!info) { + info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); + if (!info) + return -ENOMEM; + spin_lock_init(&info->ring_lock); + } else if (info->intf != NULL) { + /* already configured */ + return 0; + } + /* + * If the toolstack (or the hypervisor) hasn't set these values, the + * default value is 0. Even though gfn = 0 and evtchn = 0 are + * theoretically correct values, in practice they never are and they + * mean that a legacy toolstack hasn't initialized the pv console correctly. + */ + r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); + if (r < 0 || v == 0) + goto err; + info->evtchn = v; + v = 0; + r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v); + if (r < 0 || v == 0) + goto err; + gfn = v; + info->intf = memremap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, MEMREMAP_WB); + if (info->intf == NULL) + goto err; + info->vtermno = HVC_COOKIE; + + spin_lock_irqsave(&xencons_lock, flags); + list_add_tail(&info->list, &xenconsoles); + spin_unlock_irqrestore(&xencons_lock, flags); + + return 0; +err: + kfree(info); + return -ENODEV; +} + +static int xencons_info_pv_init(struct xencons_info *info, int vtermno) +{ + spin_lock_init(&info->ring_lock); + 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; + unsigned long flags; + + 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); + if (!info) + return -ENOMEM; + } else if (info->intf != NULL) { + /* already configured */ + return 0; + } + spin_lock_irqsave(&xencons_lock, flags); + xencons_info_pv_init(info, HVC_COOKIE); + spin_unlock_irqrestore(&xencons_lock, flags); + + return 0; +} + +static int xen_initial_domain_console_init(void) +{ + struct xencons_info *info; + unsigned long flags; + + if (!xen_initial_domain()) + return -ENODEV; + + info = vtermno_to_xencons(HVC_COOKIE); + if (!info) { + info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); + if (!info) + return -ENOMEM; + spin_lock_init(&info->ring_lock); + } + + info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false); + info->vtermno = HVC_COOKIE; + + spin_lock_irqsave(&xencons_lock, flags); + list_add_tail(&info->list, &xenconsoles); + spin_unlock_irqrestore(&xencons_lock, flags); + + return 0; +} + +static void xen_console_update_evtchn(struct xencons_info *info) +{ + if (xen_hvm_domain()) { + uint64_t v = 0; + int err; + + err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); + if (!err && v) + info->evtchn = v; + } else + info->evtchn = xen_start_info->console.domU.evtchn; +} + +void xen_console_resume(void) +{ + struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE); + if (info != NULL && info->irq) { + if (!xen_initial_domain()) + xen_console_update_evtchn(info); + rebind_evtchn_irq(info->evtchn, info->irq); + } +} + +#ifdef CONFIG_HVC_XEN_FRONTEND +static void xencons_disconnect_backend(struct xencons_info *info) +{ + if (info->hvc != NULL) + hvc_remove(info->hvc); + info->hvc = NULL; + if (info->irq > 0) { + evtchn_put(info->evtchn); + info->irq = 0; + info->evtchn = 0; + } + /* evtchn_put() will also close it so this is only an error path */ + 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; +} + +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) +{ + unsigned long flags; + + xencons_disconnect_backend(info); + spin_lock_irqsave(&xencons_lock, flags); + list_del(&info->list); + spin_unlock_irqrestore(&xencons_lock, flags); + if (info->xbdev != NULL) + xencons_free(info); + else { + if (xen_hvm_domain()) + iounmap(info->intf); + kfree(info); + } + return 0; +} + +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; + + ret = xenbus_alloc_evtchn(dev, &evtchn); + if (ret) + return ret; + info->evtchn = evtchn; + irq = bind_evtchn_to_irq_lateeoi(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); + 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, + virt_to_gfn(info->intf), 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_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 xencons_probe(struct xenbus_device *dev, + const struct xenbus_device_id *id) +{ + int ret, devid; + struct xencons_info *info; + unsigned long flags; + + devid = dev->nodename[strlen(dev->nodename) - 1] - '0'; + if (devid == 0) + return -ENODEV; + + info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); + if (!info) + return -ENOMEM; + spin_lock_init(&info->ring_lock); + 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_irqsave(&xencons_lock, flags); + list_add_tail(&info->list, &xenconsoles); + spin_unlock_irqrestore(&xencons_lock, flags); + + 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) +{ + struct xencons_info *info = dev_get_drvdata(&dev->dev); + + xencons_disconnect_backend(info); + memset(info->intf, 0, XEN_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: + break; + + case XenbusStateInitWait: + break; + + case XenbusStateConnected: + xenbus_switch_state(dev, XenbusStateConnected); + break; + + case XenbusStateClosed: + if (dev->state == XenbusStateClosed) + break; + fallthrough; /* Missed the backend's CLOSING state */ + case XenbusStateClosing: { + struct xencons_info *info = dev_get_drvdata(&dev->dev);; + + /* + * Don't tear down the evtchn and grant ref before the other + * end has disconnected, but do stop userspace from trying + * to use the device before we allow the backend to close. + */ + if (info->hvc) { + hvc_remove(info->hvc); + info->hvc = NULL; + } + + xenbus_frontend_closed(dev); + break; + } + } +} + +static const struct xenbus_device_id xencons_ids[] = { + { "console" }, + { "" } +}; + +static struct xenbus_driver xencons_driver = { + .name = "xenconsole", + .ids = xencons_ids, + .probe = xencons_probe, + .remove = xencons_remove, + .resume = xencons_resume, + .otherend_changed = xencons_backend_changed, + .not_essential = true, +}; +#endif /* CONFIG_HVC_XEN_FRONTEND */ + +static int __init xen_hvc_init(void) +{ + int r; + struct xencons_info *info; + const struct hv_ops *ops; + + if (!xen_domain()) + return -ENODEV; + + if (xen_initial_domain()) { + ops = &dom0_hvc_ops; + r = xen_initial_domain_console_init(); + if (r < 0) + goto register_fe; + info = vtermno_to_xencons(HVC_COOKIE); + } else { + ops = &domU_hvc_ops; + if (xen_hvm_domain()) + r = xen_hvm_console_init(); + else + r = xen_pv_console_init(); + if (r < 0) + goto register_fe; + + info = vtermno_to_xencons(HVC_COOKIE); + info->irq = bind_evtchn_to_irq_lateeoi(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)) { + unsigned long flags; + + r = PTR_ERR(info->hvc); + spin_lock_irqsave(&xencons_lock, flags); + list_del(&info->list); + spin_unlock_irqrestore(&xencons_lock, flags); + if (info->irq) + evtchn_put(info->evtchn); + kfree(info); + return r; + } + + r = 0; + register_fe: +#ifdef CONFIG_HVC_XEN_FRONTEND + r = xenbus_register_frontend(&xencons_driver); +#endif + return r; +} +device_initcall(xen_hvc_init); + +static int xen_cons_init(void) +{ + const struct hv_ops *ops; + + if (!xen_domain()) + return 0; + + if (xen_initial_domain()) + ops = &dom0_hvc_ops; + else { + int r; + ops = &domU_hvc_ops; + + if (xen_hvm_domain()) + r = xen_hvm_console_init(); + else + r = xen_pv_console_init(); + if (r < 0) + return r; + } + + hvc_instantiate(HVC_COOKIE, 0, ops); + return 0; +} +console_initcall(xen_cons_init); + +#ifdef CONFIG_X86 +static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) +{ + if (xen_cpuid_base()) + outsb(0xe9, str, len); +} +#else +static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { } +#endif + +#ifdef CONFIG_EARLY_PRINTK +static int __init xenboot_console_setup(struct console *console, char *string) +{ + static struct xencons_info xenboot; + + if (xen_initial_domain() || !xen_pv_domain()) + return 0; + + return xencons_info_pv_init(&xenboot, 0); +} + +static void xenboot_write_console(struct console *console, const char *string, + unsigned len) +{ + unsigned int linelen, off = 0; + const char *pos; + + if (dom0_write_console(0, string, len) >= 0) + return; + + if (!xen_pv_domain()) { + xen_hvm_early_write(0, string, len); + return; + } + + if (domU_write_console(0, "(early) ", 8) < 0) + return; + while (off < len && NULL != (pos = strchr(string+off, '\n'))) { + linelen = pos-string+off; + if (off + linelen > len) + break; + domU_write_console(0, string+off, linelen); + domU_write_console(0, "\r\n", 2); + off += linelen + 1; + } + if (off < len) + domU_write_console(0, string+off, len-off); +} + +struct console xenboot_console = { + .name = "xenboot", + .write = xenboot_write_console, + .setup = xenboot_console_setup, + .flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME, + .index = -1, +}; +#endif /* CONFIG_EARLY_PRINTK */ + +void xen_raw_console_write(const char *str) +{ + ssize_t len = strlen(str); + int rc = 0; + + if (xen_domain()) { + rc = dom0_write_console(0, str, len); + if (rc != -ENOSYS || !xen_hvm_domain()) + return; + } + xen_hvm_early_write(0, str, len); +} + +void xen_raw_printk(const char *fmt, ...) +{ + static char buf[512]; + va_list ap; + + va_start(ap, fmt); + vsnprintf(buf, sizeof(buf), fmt, ap); + va_end(ap); + + xen_raw_console_write(buf); +} + +static void xenboot_earlycon_write(struct console *console, + const char *string, + unsigned len) +{ + dom0_write_console(0, string, len); +} + +static int __init xenboot_earlycon_setup(struct earlycon_device *device, + const char *opt) +{ + device->con->write = xenboot_earlycon_write; + return 0; +} +EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup); |