Don't require a separate domctl to notify the memevent interface that an event
has occured.  This domctl can be taxing, particularly when you are scaling
events and paging to many domains across a single system.  Instead, we use the
existing event channel to signal when we place something in the ring (as per
normal ring operation).

Signed-off-by: Adin Scannell <adin@scannell.ca>

diff -r e581ed816224 xen/arch/ia64/xen/Makefile
--- a/xen/arch/ia64/xen/Makefile
+++ b/xen/arch/ia64/xen/Makefile
@@ -38,6 +38,7 @@ obj-y += flushd.o
 obj-y += privop_stat.o
 obj-y += xenpatch.o
 obj-y += pci.o
+obj-y += events.o
 
 obj-$(crash_debug) += gdbstub.o
 obj-$(xen_ia64_tlb_track) += tlb_track.o
diff -r e581ed816224 xen/arch/ia64/xen/events.c
--- /dev/null
+++ b/xen/arch/ia64/xen/events.c
@@ -0,0 +1,27 @@
+/******************************************************************************
+ * events.c
+ * 
+ * Arch-specific event channels.
+ */
+
+#include <xen/config.h>
+#include <xen/errno.h>
+#include <xen/sched.h>
+#include <xen/event.h>
+
+int arch_event_notify(struct vcpu *v, int port)
+{
+    int ret = 0;
+
+    if( port == v->arch.hvm_vcpu.xen_port )
+    {
+        if( test_and_clear_bit(_VPF_blocked_in_xen, &v->pause_flags) )
+            vcpu_wake(v);
+    }
+    else
+    {
+        ret = -EINVAL;
+    }
+
+    return ret;
+}
diff -r e581ed816224 xen/arch/x86/Makefile
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -57,6 +57,7 @@ obj-y += crash.o
 obj-y += tboot.o
 obj-y += hpet.o
 obj-y += xstate.o
+obj-y += events.o
 
 obj-$(crash_debug) += gdbstub.o
 
diff -r e581ed816224 xen/arch/x86/events.c
--- /dev/null
+++ b/xen/arch/x86/events.c
@@ -0,0 +1,41 @@
+/******************************************************************************
+ * events.c
+ * 
+ * Arch-specific event channels.
+ */
+
+#include <xen/config.h>
+#include <xen/errno.h>
+#include <xen/sched.h>
+#include <xen/event.h>
+#include <asm/mem_event.h>
+#include <asm/mem_sharing.h>
+
+int arch_event_notify(struct vcpu *v, int port)
+{
+    int ret = 0;
+
+    if( port == v->arch.hvm_vcpu.xen_port )
+    {
+        if( test_and_clear_bit(_VPF_blocked_in_xen, &v->pause_flags) )
+            vcpu_wake(v);
+    }
+    else if ( port == v->domain->mem_paging.xen_port )
+    {
+        ret = p2m_mem_paging_resume(v->domain);
+    }
+    else if ( port == v->domain->mem_access.xen_port )
+    {
+        ret = p2m_mem_access_resume(v->domain);
+    }
+    else if ( port == v->domain->mem_share.xen_port )
+    {
+        ret = mem_sharing_sharing_resume(v->domain);
+    }
+    else
+    {
+        ret = -EINVAL;
+    }
+
+    return ret;
+}
diff -r e581ed816224 xen/arch/x86/mm/mem_access.c
--- a/xen/arch/x86/mm/mem_access.c
+++ b/xen/arch/x86/mm/mem_access.c
@@ -29,13 +29,12 @@ int mem_access_domctl(struct domain *d, 
                       XEN_GUEST_HANDLE(void) u_domctl)
 {
     int rc;
-    struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
     switch( mec->op )
     {
     case XEN_DOMCTL_MEM_EVENT_OP_ACCESS_RESUME:
     {
-        p2m_mem_access_resume(p2m);
+        p2m_mem_access_resume(d);
         rc = 0;
     }
     break;
diff -r e581ed816224 xen/arch/x86/mm/mem_paging.c
--- a/xen/arch/x86/mm/mem_paging.c
+++ b/xen/arch/x86/mm/mem_paging.c
@@ -64,7 +64,6 @@ int mem_paging_domctl(struct domain *d, 
     }
 }
 
-
 /*
  * Local variables:
  * mode: C
diff -r e581ed816224 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -833,7 +833,7 @@ int p2m_mem_paging_prep(struct domain *d
     return 0;
 }
 
-void p2m_mem_paging_resume(struct domain *d)
+int p2m_mem_paging_resume(struct domain *d)
 {
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
     mem_event_response_t rsp;
@@ -861,6 +861,8 @@ void p2m_mem_paging_resume(struct domain
 
     /* Unpause any domains that were paused because the ring was full */
     mem_event_unpause_vcpus(d, &d->mem_paging);
+
+    return 0;
 }
 
 void p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, unsigned long gla, 
@@ -936,9 +938,8 @@ void p2m_mem_access_check(unsigned long 
     /* VCPU paused, mem event request sent */
 }
 
-void p2m_mem_access_resume(struct p2m_domain *p2m)
+int p2m_mem_access_resume(struct domain *d)
 {
-    struct domain *d = p2m->domain;
     mem_event_response_t rsp;
 
     /* Pull all responses off the ring */
@@ -952,6 +953,8 @@ void p2m_mem_access_resume(struct p2m_do
     /* Unpause any domains that were paused because the ring was full or no listener 
      * was available */
     mem_event_unpause_vcpus(d, &d->mem_access);
+
+    return 0;
 }
 
 
diff -r e581ed816224 xen/common/event_channel.c
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -57,6 +57,8 @@
         goto out;                                                   \
     } while ( 0 )
 
+extern int arch_event_notify(struct vcpu *v, int port);
+
 static int evtchn_set_pending(struct vcpu *v, int port);
 
 static int virq_is_global(int virq)
@@ -553,10 +555,7 @@ int evtchn_send(struct domain *d, unsign
         rvcpu = rd->vcpu[rchn->notify_vcpu_id];
         if ( rchn->consumer_is_xen )
         {
-            /* Xen consumers need notification only if they are blocked. */
-            if ( test_and_clear_bit(_VPF_blocked_in_xen,
-                                    &rvcpu->pause_flags) )
-                vcpu_wake(rvcpu);
+            ret = arch_event_notify(rvcpu, rport);
         }
         else
         {
diff -r e581ed816224 xen/include/asm-x86/mem_event.h
--- a/xen/include/asm-x86/mem_event.h
+++ b/xen/include/asm-x86/mem_event.h
@@ -24,6 +24,8 @@
 #ifndef __MEM_EVENT_H__
 #define __MEM_EVENT_H__
 
+#include <asm/p2m.h>
+
 /* Pauses VCPU while marking pause flag for mem event */
 void mem_event_mark_and_pause(struct vcpu *v, struct mem_event_domain *med);
 int mem_event_check_ring(struct domain *d, struct mem_event_domain *med);
diff -r e581ed816224 xen/include/asm-x86/mem_sharing.h
--- a/xen/include/asm-x86/mem_sharing.h
+++ b/xen/include/asm-x86/mem_sharing.h
@@ -47,6 +47,9 @@ void mem_sharing_init(void);
 
 #define mem_sharing_init()  do { } while (0)
 
+static inline int mem_sharing_sharing_resume(struct domain *d)
+{ return -EINVAL; }
+
 #endif /* __x86_64__ */
 
 #endif /* __MEM_SHARING_H__ */
diff -r e581ed816224 xen/include/asm-x86/p2m.h
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -489,12 +489,14 @@ void p2m_mem_paging_populate(struct doma
 /* Prepare the p2m for paging a frame in */
 int p2m_mem_paging_prep(struct domain *d, unsigned long gfn);
 /* Resume normal operation (in case a domain was paused) */
-void p2m_mem_paging_resume(struct domain *d);
+int p2m_mem_paging_resume(struct domain *d);
 #else
 static inline void p2m_mem_paging_drop_page(struct domain *d, unsigned long gfn)
 { }
 static inline void p2m_mem_paging_populate(struct domain *d, unsigned long gfn)
 { }
+static inline int p2m_mem_paging_resume(struct domain *d)
+{ return -EINVAL; }
 #endif
 
 #ifdef __x86_64__
@@ -503,7 +505,7 @@ static inline void p2m_mem_paging_popula
 void p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, unsigned long gla, 
                           bool_t access_r, bool_t access_w, bool_t access_x);
 /* Resumes the running of the VCPU, restarting the last instruction */
-void p2m_mem_access_resume(struct p2m_domain *p2m);
+int p2m_mem_access_resume(struct domain *d);
 
 /* Set access type for a region of pfns.
  * If start_pfn == -1ul, sets the default access type */
@@ -527,6 +529,8 @@ static inline int p2m_set_mem_access(str
 static inline int p2m_get_mem_access(struct domain *d, unsigned long pfn, 
                                      hvmmem_access_t *access)
 { return -EINVAL; }
+static inline int p2m_mem_access_resume(struct domain *d)
+{ return -EINVAL; }
 #endif
 
 /*