[PATCH 03/11] xen/arm: vpl011: Refactor evtchn_send in Xen to allow sending events from a xen bound channel

[Bhupinder Thakur <bhupinder.thakur@linaro.org>]

Breakup evtchn_send() to allow sending events for a Xen bound channel. Currently,
there is a check in evtchn_send() i.e. is_consumer_xen() that if the event channel
is bound to a xen consumer then event generation is not allowed for that channel.
This check is to disallow a guest from raising an event via this channel. However,
it should allow Xen to send a event via this channel as it is required for sending
vpl011 event to the dom0.

This change introduces a new function raw_evtchn_send() which sends the event
without this check. The current evtchn_send() calls this function after doing the
xen consumer check. Xen uses the raw_evtchm_send() version to send the event thus
bypassing the check.

Signed-off-by: Bhupinder Thakur <bhupinder.thakur@linaro.org>
---
 xen/common/event_channel.c | 49 ++++++++++++++++++++++++++++++++++------------
 xen/include/xen/event.h    |  6 ++++++
 2 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 638dc5e..4b039f3 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -27,6 +27,7 @@
 #include <xen/keyhandler.h>
 #include <xen/event_fifo.h>
 #include <asm/current.h>
+#include <xen/domain_page.h>
 
 #include <public/xen.h>
 #include <public/event_channel.h>
@@ -650,25 +651,21 @@ static long evtchn_close(struct domain *d1, int port1, bool_t guest)
     return rc;
 }
 
-int evtchn_send(struct domain *ld, unsigned int lport)
+int raw_evtchn_send(struct domain *ld, unsigned int lport, void *data)
 {
     struct evtchn *lchn, *rchn;
     struct domain *rd;
-    int            rport, ret = 0;
+    int rport, ret=0;
 
-    if ( !port_is_valid(ld, lport) )
-        return -EINVAL;
-
-    lchn = evtchn_from_port(ld, lport);
-
-    spin_lock(&lchn->lock);
-
-    /* Guest cannot send via a Xen-attached event channel. */
-    if ( unlikely(consumer_is_xen(lchn)) )
+    if ( !data )
     {
-        ret = -EINVAL;
-        goto out;
+        if ( !port_is_valid(ld, lport) )
+            return -EINVAL;
+        lchn = evtchn_from_port(ld, lport);
+        spin_lock(&lchn->lock);
     }
+    else
+        lchn = (struct evtchn *)data; 
 
     ret = xsm_evtchn_send(XSM_HOOK, ld, lchn);
     if ( ret )
@@ -696,6 +693,32 @@ int evtchn_send(struct domain *ld, unsigned int lport)
     }
 
 out:
+    if ( !data )
+        spin_unlock(&lchn->lock);
+
+    return ret;
+}
+
+int evtchn_send(struct domain *ld, unsigned int lport)
+{
+    struct evtchn *lchn;
+    int ret;
+
+    if ( !port_is_valid(ld, lport) )
+        return -EINVAL;
+
+    lchn = evtchn_from_port(ld, lport);
+
+    spin_lock(&lchn->lock);
+
+    if ( unlikely(consumer_is_xen(lchn)) )
+    {
+        printk("evtchn_send failed to send via xen event channel\n");
+        return -EINVAL;
+    }
+
+    ret = raw_evtchn_send(ld, lport, lchn);
+
     spin_unlock(&lchn->lock);
 
     return ret;
diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index 5008c80..9bd17db 100644
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -45,6 +45,12 @@ void send_guest_pirq(struct domain *, const struct pirq *);
 /* Send a notification from a given domain's event-channel port. */
 int evtchn_send(struct domain *d, unsigned int lport);
 
+/* 
+ * This function is same as evntchn_send() except it does not do xen consumer check
+ * to allow the events to be sent from xen bound channels.
+ */
+int raw_evtchn_send(struct domain *ld, unsigned int lport, void *data);
+
 /* Bind a local event-channel port to the specified VCPU. */
 long evtchn_bind_vcpu(unsigned int port, unsigned int vcpu_id);
 
-- 
2.7.4


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