From: Tim Deegan <tim@xen.org>
Date: Thu, 8 Mar 2012 16:40:05 +0000 (+0000)
Subject: x86/mm: wire up sharing ring
X-Git-Tag: 4.2.0-rc1~666
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=cc0b0b4487dd1df3fd5e15050a2fb05bb88b3539;p=xen.git

x86/mm: wire up sharing ring

Now that we have an interface close to finalizing, do the necessary plumbing to
set up a ring for reporting failed allocations in the unshare path.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>
---

diff --git a/xen/arch/x86/mm/mem_event.c b/xen/arch/x86/mm/mem_event.c
index b6dde8d0de..79cb44859a 100644
--- a/xen/arch/x86/mm/mem_event.c
+++ b/xen/arch/x86/mm/mem_event.c
@@ -431,6 +431,13 @@ static void mem_access_notification(struct vcpu *v, unsigned int port)
         p2m_mem_access_resume(v->domain);
 }
 
+/* Registered with Xen-bound event channel for incoming notifications. */
+static void mem_sharing_notification(struct vcpu *v, unsigned int port)
+{
+    if ( likely(v->domain->mem_event->share.ring_page != NULL) )
+        mem_sharing_sharing_resume(v->domain);
+}
+
 struct domain *get_mem_event_op_target(uint32_t domain, int *rc)
 {
     struct domain *d;
@@ -598,6 +605,40 @@ int mem_event_domctl(struct domain *d, xen_domctl_mem_event_op_t *mec,
     }
     break;
 
+    case XEN_DOMCTL_MEM_EVENT_OP_SHARING: 
+    {
+        struct mem_event_domain *med = &d->mem_event->share;
+        rc = -EINVAL;
+
+        switch( mec->op )
+        {
+        case XEN_DOMCTL_MEM_EVENT_OP_SHARING_ENABLE:
+        {
+            rc = -ENODEV;
+            /* Only HAP is supported */
+            if ( !hap_enabled(d) )
+                break;
+
+            rc = mem_event_enable(d, mec, med, _VPF_mem_sharing, 
+                                    HVM_PARAM_SHARING_RING_PFN,
+                                    mem_sharing_notification);
+        }
+        break;
+
+        case XEN_DOMCTL_MEM_EVENT_OP_SHARING_DISABLE:
+        {
+            if ( med->ring_page )
+                rc = mem_event_disable(d, med);
+        }
+        break;
+
+        default:
+            rc = -ENOSYS;
+            break;
+        }
+    }
+    break;
+
     default:
         rc = -ENOSYS;
     }
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index a3ed8d76be..494520743d 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -711,7 +711,7 @@ struct xen_domctl_gdbsx_domstatus {
 /* XEN_DOMCTL_mem_event_op */
 
 /*
-* Domain memory paging
+ * Domain memory paging
  * Page memory in and out.
  * Domctl interface to set up and tear down the 
  * pager<->hypervisor interface. Use XENMEM_paging_op*
@@ -741,6 +741,24 @@ struct xen_domctl_gdbsx_domstatus {
 #define XEN_DOMCTL_MEM_EVENT_OP_ACCESS_ENABLE     0
 #define XEN_DOMCTL_MEM_EVENT_OP_ACCESS_DISABLE    1
 
+/*
+ * Sharing ENOMEM helper.
+ *
+ * As with paging, use the domctl for teardown/setup of the
+ * helper<->hypervisor interface.
+ *
+ * If setup, this ring is used to communicate failed allocations
+ * in the unshare path. XENMEM_sharing_op_resume is used to wake up
+ * vcpus that could not unshare.
+ *
+ * Note that shring can be turned on (as per the domctl below)
+ * *without* this ring being setup.
+ */
+#define XEN_DOMCTL_MEM_EVENT_OP_SHARING           3
+
+#define XEN_DOMCTL_MEM_EVENT_OP_SHARING_ENABLE    0
+#define XEN_DOMCTL_MEM_EVENT_OP_SHARING_DISABLE   1
+
 /* Use for teardown/setup of helper<->hypervisor interface for paging, 
  * access and sharing.*/
 struct xen_domctl_mem_event_op {
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 65219cf988..53804c87d5 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -636,6 +636,9 @@ static inline struct domain *next_domain_in_cpupool(
  /* VCPU is blocked due to missing mem_access ring. */
 #define _VPF_mem_access      5
 #define VPF_mem_access       (1UL<<_VPF_mem_access)
+ /* VCPU is blocked due to missing mem_sharing ring. */
+#define _VPF_mem_sharing     6
+#define VPF_mem_sharing      (1UL<<_VPF_mem_sharing)
 
 static inline int vcpu_runnable(struct vcpu *v)
 {