[RESEND PATCH v2 06/18] xen: Port Xen event channel driver from mini-os

Anastasiia Lukianenko
2020-08-06T09:42:49Z

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Make required updates to run on u-boot. Strip functionality
not needed by U-boot.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
---

Changes since v1:
- correct code style
- remove typedefs
- add comments

drivers/xen/Makefile | 1 +
drivers/xen/events.c | 195 +++++++++++++++++++++++++++++++++++++++
drivers/xen/hypervisor.c | 6 +-
include/xen.h | 2 +-
include/xen/events.h | 42 +++++++++
5 files changed, 242 insertions(+), 4 deletions(-)
create mode 100644 drivers/xen/events.c
create mode 100644 include/xen/events.h

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 1211bf2386..0ad35edefb 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -3,3 +3,4 @@
# (C) Copyright 2020 EPAM Systems Inc.

obj-y += hypervisor.o
+obj-y += events.o
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
new file mode 100644
index 0000000000..b4c84814c5
--- /dev/null
+++ b/drivers/xen/events.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) 2003 - Rolf Neugebauer - Intel Research Cambridge
+ * (C) 2005 - Grzegorz Milos - Intel Research Cambridge
+ * (C) 2020 - EPAM Systems Inc.
+ *
+ * File: events.c [1]
+ * Author: Rolf Neugebauer (neugebar at dcs.gla.ac.uk)
+ * Changes: Grzegorz Milos (gm281 at cam.ac.uk)
+ *
+ * Date: Jul 2003, changes Jun 2005
+ *
+ * Description: Deals with events received on event channels
+ *
+ * [1] - http://xenbits.xen.org/gitweb/?p=mini-os.git;a=summary
+ */
+#include <common.h>
+#include <log.h>
+
+#include <asm/io.h>
+#include <asm/xen/system.h>
+
+#include <xen/events.h>
+#include <xen/hvm.h>
+
+#define NR_EVS 1024
+
+/**
+ * struct _ev_action - represents a event handler.
+ *
+ * Chaining or sharing is not allowed
+ */
+struct _ev_action {
+ void (*handler)(evtchn_port_t port, struct pt_regs *regs, void *data);
+ void *data;
+ u32 count;
+};
+
+static struct _ev_action ev_actions[NR_EVS];
+void default_handler(evtchn_port_t port, struct pt_regs *regs, void *data);
+
+static unsigned long bound_ports[NR_EVS / (8 * sizeof(unsigned long))];
+
+void unbind_all_ports(void)
+{
+ int i;
+ int cpu = 0;
+ struct shared_info *s = HYPERVISOR_shared_info;
+ struct vcpu_info *vcpu_info = &s->vcpu_info[cpu];
+
+ for (i = 0; i < NR_EVS; i++) {
+ if (test_and_clear_bit(i, bound_ports)) {
+ printf("port %d still bound!\n", i);
+ unbind_evtchn(i);
+ }
+ }
+ vcpu_info->evtchn_upcall_pending = 0;
+ vcpu_info->evtchn_pending_sel = 0;
+}
+
+int do_event(evtchn_port_t port, struct pt_regs *regs)
+{
+ struct _ev_action *action;
+
+ clear_evtchn(port);
+
+ if (port >= NR_EVS) {
+ printk("WARN: do_event(): Port number too large: %d\n", port);
+ return 1;
+ }
+
+ action = &ev_actions[port];
+ action->count++;
+
+ /* call the handler */
+ action->handler(port, regs, action->data);
+
+ return 1;
+}
+
+evtchn_port_t bind_evtchn(evtchn_port_t port,
+ void (*handler)(evtchn_port_t, struct pt_regs *, void *),
+ void *data)
+{
+ if (ev_actions[port].handler != default_handler)
+ printf("WARN: Handler for port %d already registered, replacing\n",
+ port);
+
+ ev_actions[port].data = data;
+ wmb();
+ ev_actions[port].handler = handler;
+ synch_set_bit(port, bound_ports);
+
+ return port;
+}
+
+/**
+ * unbind_evtchn() - Unbind event channel for selected port
+ */
+void unbind_evtchn(evtchn_port_t port)
+{
+ struct evtchn_close close;
+ int rc;
+
+ if (ev_actions[port].handler == default_handler)
+ printf("WARN: No handler for port %d when unbinding\n", port);
+ mask_evtchn(port);
+ clear_evtchn(port);
+
+ ev_actions[port].handler = default_handler;
+ wmb();
+ ev_actions[port].data = NULL;
+ synch_clear_bit(port, bound_ports);
+
+ close.port = port;
+ rc = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
+ if (rc)
+ printf("WARN: close_port %d failed rc=%d. ignored\n", port, rc);
+}
+
+void default_handler(evtchn_port_t port, struct pt_regs *regs, void *ignore)
+{
+ debug("[Port %d] - event received\n", port);
+}
+
+/**
+ * evtchn_alloc_unbound() - Create a port available to the pal for
+ * exchanging notifications.
+ *
+ * Unfortunate confusion of terminology: the port is unbound as far
+ * as Xen is concerned, but we automatically bind a handler to it.
+ *
+ * Return: The result of the hypervisor call.
+ */
+int evtchn_alloc_unbound(domid_t pal,
+ void (*handler)(evtchn_port_t, struct pt_regs *, void *),
+ void *data, evtchn_port_t *port)
+{
+ int rc;
+
+ struct evtchn_alloc_unbound op;
+
+ op.dom = DOMID_SELF;
+ op.remote_dom = pal;
+ rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &op);
+ if (rc) {
+ printf("ERROR: alloc_unbound failed with rc=%d", rc);
+ return rc;
+ }
+ if (!handler)
+ handler = default_handler;
+ *port = bind_evtchn(op.port, handler, data);
+ return rc;
+}
+
+/**
+ * eventchn_poll() - Event channel polling function
+ *
+ * Check and process any pending events
+ */
+void eventchn_poll(void)
+{
+ do_hypervisor_callback(NULL);
+}
+
+/**
+ * init_events() - Initialize event handler
+ *
+ * Initially all events are without a handler and disabled.
+ */
+void init_events(void)
+{
+ int i;
+
+ debug("%s\n", __func__);
+
+ for (i = 0; i < NR_EVS; i++) {
+ ev_actions[i].handler = default_handler;
+ mask_evtchn(i);
+ }
+}
+
+/**
+ * fini_events() - Close all ports
+ *
+ * Mask and clear event channels. Close port using EVTCHNOP_close
+ * hypercall.
+ */
+void fini_events(void)
+{
+ debug("%s\n", __func__);
+ /* Dealloc all events */
+ unbind_all_ports();
+}
+
diff --git a/drivers/xen/hypervisor.c b/drivers/xen/hypervisor.c
index 108e9701d6..63fed6074f 100644
--- a/drivers/xen/hypervisor.c
+++ b/drivers/xen/hypervisor.c
@@ -20,6 +20,7 @@
#include <linux/bug.h>

#include <xen/hvm.h>
+#include <xen/events.h>
#include <xen/interface/memory.h>

#define active_evtchns(cpu, sh, idx) \
@@ -163,9 +164,7 @@ void do_hypervisor_callback(struct pt_regs *regs)
l2 &= ~(1UL << l2i);

port = (l1i * (sizeof(unsigned long) * 8)) + l2i;
- /* TODO: handle new event: do_event(port, regs); */
- /* Suppress -Wunused-but-set-variable */
- (void)(port);
+ do_event(port, regs);
}
}

@@ -236,5 +235,6 @@ void xen_init(void)
debug("%s\n", __func__);

map_shared_info(NULL);
+ init_events();
}

diff --git a/include/xen.h b/include/xen.h
index abc3546dd2..64ed3f0654 100644
--- a/include/xen.h
+++ b/include/xen.h
@@ -8,7 +8,7 @@
/**
* xen_init() - Xen initialization
*
- * Map Xen memory pages.
+ * Map Xen memory pages, initialize event handler.
*/
void xen_init(void);

diff --git a/include/xen/events.h b/include/xen/events.h
new file mode 100644
index 0000000000..82bd18b48c
--- /dev/null
+++ b/include/xen/events.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * (C) 2003 - Rolf Neugebauer - Intel Research Cambridge
+ * (C) 2005 - Grzegorz Milos - Intel Reseach Cambridge
+ * (C) 2020 - EPAM Systems Inc.
+ *
+ * File: events.h
+ * Author: Rolf Neugebauer (neugebar at dcs.gla.ac.uk)
+ * Changes: Grzegorz Milos (gm281@cam.ac.uk)
+ *
+ * Date: Jul 2003, changes Jun 2005
+ *
+ * Description: Deals with events on the event channels
+ */
+#ifndef _EVENTS_H_
+#define _EVENTS_H_
+
+#include <asm/xen/hypercall.h>
+#include <xen/interface/event_channel.h>
+
+void init_events(void);
+void fini_events(void);
+
+int do_event(evtchn_port_t port, struct pt_regs *regs);
+void unbind_evtchn(evtchn_port_t port);
+void unbind_all_ports(void);
+int evtchn_alloc_unbound(domid_t pal,
+ void (*handler)(evtchn_port_t, struct pt_regs *, void *),
+ void *data, evtchn_port_t *port);
+
+/* Send notification via event channel */
+static inline int notify_remote_via_evtchn(evtchn_port_t port)
+{
+ struct evtchn_send op;
+
+ op.port = port;
+ return HYPERVISOR_event_channel_op(EVTCHNOP_send, &op);
+}
+
+void eventchn_poll(void);
+
+#endif /* _EVENTS_H_ */
--
2.17.1