[RFC PATCH V3 11/12] xen/vm_event: Decouple vm_event and mem_access.

[Tamas K Lengyel <tamas.lengyel@zentific.com>]

The vm_event subsystem has been artifically tied to the presence of mem_access.
While mem_access does depend on vm_event, vm_event is an entirely independent
subsystem that can be used for arbitrary function-offloading to helper apps in
domains. This patch removes the dependency that mem_access needs to be supported
in order to enable vm_event.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
---
v3: Move ring processing out from mem_access.c to monitor.c in common
---
 MAINTAINERS                  |  1 +
 xen/common/Makefile          |  3 ++-
 xen/common/mem_access.c      | 32 ++--------------------
 xen/common/monitor.c         | 64 ++++++++++++++++++++++++++++++++++++++++++++
 xen/common/vm_event.c        | 14 +++-------
 xen/include/xen/mem_access.h | 10 ++++---
 xen/include/xen/monitor.h    | 38 ++++++++++++++++++++++++++
 xen/include/xen/vm_event.h   | 56 --------------------------------------
 xen/include/xsm/dummy.h      |  2 --
 xen/include/xsm/xsm.h        |  4 ---
 xen/xsm/dummy.c              |  2 --
 xen/xsm/flask/hooks.c        | 32 +++++++++-------------
 12 files changed, 131 insertions(+), 127 deletions(-)
 create mode 100644 xen/common/monitor.c
 create mode 100644 xen/include/xen/monitor.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 4c445bb..5d88d85 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -365,6 +365,7 @@ VM EVENT AND ACCESS
 M:	Tim Deegan <tim@xen.org>
 S:	Supported
 F:	xen/common/vm_event.c
+F:	xen/common/monitor.c
 F:	xen/common/mem_access.c
 
 XENTRACE
diff --git a/xen/common/Makefile b/xen/common/Makefile
index e5bd75b..d86c073 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -52,9 +52,10 @@ obj-y += tmem_xen.o
 obj-y += radix-tree.o
 obj-y += rbtree.o
 obj-y += lzo.o
+obj-y += vm_event.o
+obj-y += monitor.o
 obj-$(HAS_PDX) += pdx.o
 obj-$(HAS_MEM_ACCESS) += mem_access.o
-obj-$(HAS_MEM_ACCESS) += vm_event.o
 
 obj-bin-$(CONFIG_X86) += $(foreach n,decompress bunzip2 unxz unlzma unlzo unlz4 earlycpio,$(n).init.o)
 
diff --git a/xen/common/mem_access.c b/xen/common/mem_access.c
index 1f655b0..3655165 100644
--- a/xen/common/mem_access.c
+++ b/xen/common/mem_access.c
@@ -25,39 +25,11 @@
 #include <xen/guest_access.h>
 #include <xen/hypercall.h>
 #include <xen/vm_event.h>
+#include <xen/monitor.h>
 #include <public/memory.h>
 #include <asm/p2m.h>
 #include <xsm/xsm.h>
 
-void mem_access_resume(struct domain *d)
-{
-    vm_event_response_t rsp;
-
-    /* Pull all responses off the ring. */
-    while ( vm_event_get_response(d, &d->vm_event->monitor, &rsp) )
-    {
-        struct vcpu *v;
-
-        if ( rsp.version != VM_EVENT_INTERFACE_VERSION )
-            continue;
-
-        if ( rsp.flags & VM_EVENT_FLAG_DUMMY )
-            continue;
-
-        /* Validate the vcpu_id in the response. */
-        if ( (rsp.vcpu_id >= d->max_vcpus) || !d->vcpu[rsp.vcpu_id] )
-            continue;
-
-        v = d->vcpu[rsp.vcpu_id];
-
-        p2m_vm_event_emulate_check(v, &rsp);
-
-        /* Unpause domain. */
-        if ( rsp.flags & VM_EVENT_FLAG_VCPU_PAUSED )
-            vm_event_vcpu_unpause(v);
-    }
-}
-
 int mem_access_memop(unsigned long cmd,
                      XEN_GUEST_HANDLE_PARAM(xen_mem_access_op_t) arg)
 {
@@ -92,7 +64,7 @@ int mem_access_memop(unsigned long cmd,
             rc = -ENOSYS;
         else
         {
-            mem_access_resume(d);
+            monitor_resume(d);
             rc = 0;
         }
         break;
diff --git a/xen/common/monitor.c b/xen/common/monitor.c
new file mode 100644
index 0000000..172381a
--- /dev/null
+++ b/xen/common/monitor.c
@@ -0,0 +1,64 @@
+/******************************************************************************
+ * monitor.c
+ *
+ * VM event monitor support.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <xen/sched.h>
+#include <xen/vm_event.h>
+#include <xen/mem_access.h>
+
+void monitor_resume(struct domain *d)
+{
+    vm_event_response_t rsp;
+
+    /* Pull all responses off the ring. */
+    while ( vm_event_get_response(d, &d->vm_event->monitor, &rsp) )
+    {
+        struct vcpu *v;
+
+        if ( rsp.version != VM_EVENT_INTERFACE_VERSION )
+            continue;
+
+#ifndef NDEBUG
+        if ( rsp.flags & VM_EVENT_FLAG_DUMMY )
+            continue;
+#endif
+
+        /* Validate the vcpu_id in the response. */
+        if ( (rsp.vcpu_id >= d->max_vcpus) || !d->vcpu[rsp.vcpu_id] )
+            continue;
+
+        v = d->vcpu[rsp.vcpu_id];
+
+        if ( rsp.reason == VM_EVENT_REASON_MEM_ACCESS )
+            mem_access_resume(v, &rsp);
+
+        /* Unpause domain. */
+        if ( rsp.flags & VM_EVENT_FLAG_VCPU_PAUSED )
+            vm_event_vcpu_unpause(v);
+    }
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index 0b30750..7eba58c 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -25,7 +25,7 @@
 #include <xen/event.h>
 #include <xen/wait.h>
 #include <xen/vm_event.h>
-#include <xen/mem_access.h>
+#include <xen/monitor.h>
 #include <asm/p2m.h>
 
 #ifdef HAS_MEM_PAGING
@@ -439,14 +439,12 @@ static void mem_paging_notification(struct vcpu *v, unsigned int port)
 }
 #endif
 
-#ifdef HAS_MEM_ACCESS
 /* Registered with Xen-bound event channel for incoming notifications. */
-static void mem_access_notification(struct vcpu *v, unsigned int port)
+static void monitor_notification(struct vcpu *v, unsigned int port)
 {
     if ( likely(v->domain->vm_event->monitor.ring_page != NULL) )
-        mem_access_resume(v->domain);
+        monitor_resume(v->domain);
 }
-#endif
 
 #ifdef HAS_MEM_SHARING
 /* Registered with Xen-bound event channel for incoming notifications. */
@@ -507,12 +505,10 @@ void vm_event_cleanup(struct domain *d)
         (void)vm_event_disable(d, &d->vm_event->paging);
     }
 #endif
-#ifdef HAS_MEM_ACCESS
     if ( d->vm_event->monitor.ring_page ) {
         destroy_waitqueue_head(&d->vm_event->monitor.wq);
         (void)vm_event_disable(d, &d->vm_event->monitor);
     }
-#endif
 #ifdef HAS_MEM_SHARING
     if ( d->vm_event->share.ring_page ) {
         destroy_waitqueue_head(&d->vm_event->share.wq);
@@ -608,7 +604,6 @@ int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
     break;
 #endif
 
-#ifdef HAS_MEM_ACCESS
     case XEN_DOMCTL_VM_EVENT_OP_MONITOR:
     {
         struct vm_event_domain *ved = &d->vm_event->monitor;
@@ -620,7 +615,7 @@ int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
         {
             rc = vm_event_enable(d, vec, ved, _VPF_mem_access,
                                     HVM_PARAM_MONITOR_RING_PFN,
-                                    mem_access_notification);
+                                    monitor_notification);
         }
         break;
 
@@ -639,7 +634,6 @@ int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
         }
     }
     break;
-#endif
 
 #ifdef HAS_MEM_SHARING
     case XEN_DOMCTL_VM_EVENT_OP_SHARING:
diff --git a/xen/include/xen/mem_access.h b/xen/include/xen/mem_access.h
index 1d01221..aed2e13 100644
--- a/xen/include/xen/mem_access.h
+++ b/xen/include/xen/mem_access.h
@@ -24,6 +24,7 @@
 #define _XEN_ASM_MEM_ACCESS_H
 
 #include <public/memory.h>
+#include <asm/p2m.h>
 
 #ifdef HAS_MEM_ACCESS
 
@@ -31,8 +32,11 @@ int mem_access_memop(unsigned long cmd,
                      XEN_GUEST_HANDLE_PARAM(xen_mem_access_op_t) arg);
 int mem_access_send_req(struct domain *d, vm_event_request_t *req);
 
-/* Resumes the running of the VCPU, restarting the last instruction */
-void mem_access_resume(struct domain *d);
+static inline
+void mem_access_resume(struct vcpu *v, vm_event_response_t *rsp)
+{
+    p2m_vm_event_emulate_check(v, rsp);
+}
 
 #else
 
@@ -49,7 +53,7 @@ int mem_access_send_req(struct domain *d, vm_event_request_t *req)
     return -ENOSYS;
 }
 
-static inline void mem_access_resume(struct domain *d) {}
+static inline void mem_access_resume(struct vcpu *vcpu, vm_event_response_t *rsp) {}
 
 #endif /* HAS_MEM_ACCESS */
 
diff --git a/xen/include/xen/monitor.h b/xen/include/xen/monitor.h
new file mode 100644
index 0000000..aad821b
--- /dev/null
+++ b/xen/include/xen/monitor.h
@@ -0,0 +1,38 @@
+/******************************************************************************
+ * monitor.h
+ *
+ * Monitor event support.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _XEN_ASM_MONITOR_H
+#define _XEN_ASM_MONITOR_H
+
+#include <public/memory.h>
+
+/* Resumes the running of the VCPU, restarting the last instruction */
+void monitor_resume(struct domain *d);
+
+#endif /* _XEN_ASM_MEM_ACCESS_H */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/xen/vm_event.h b/xen/include/xen/vm_event.h
index 988ea42..477ef7e 100644
--- a/xen/include/xen/vm_event.h
+++ b/xen/include/xen/vm_event.h
@@ -26,8 +26,6 @@
 
 #include <xen/sched.h>
 
-#ifdef HAS_MEM_ACCESS
-
 /* Clean up on domain destruction */
 void vm_event_cleanup(struct domain *d);
 
@@ -76,60 +74,6 @@ int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *mec,
 void vm_event_vcpu_pause(struct vcpu *v);
 void vm_event_vcpu_unpause(struct vcpu *v);
 
-#else
-
-static inline void vm_event_cleanup(struct domain *d) {}
-
-static inline bool_t vm_event_check_ring(struct vm_event_domain *med)
-{
-    return 0;
-}
-
-static inline int vm_event_claim_slot(struct domain *d,
-                                        struct vm_event_domain *med)
-{
-    return -ENOSYS;
-}
-
-static inline int vm_event_claim_slot_nosleep(struct domain *d,
-                                        struct vm_event_domain *med)
-{
-    return -ENOSYS;
-}
-
-static inline
-void vm_event_cancel_slot(struct domain *d, struct vm_event_domain *med)
-{}
-
-static inline
-void vm_event_put_request(struct domain *d, struct vm_event_domain *med,
-                            vm_event_request_t *req)
-{}
-
-static inline
-int vm_event_get_response(struct domain *d, struct vm_event_domain *med,
-                           vm_event_response_t *rsp)
-{
-    return -ENOSYS;
-}
-
-static inline int do_vm_event_op(int op, uint32_t domain, void *arg)
-{
-    return -ENOSYS;
-}
-
-static inline
-int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *mec,
-                     XEN_GUEST_HANDLE_PARAM(void) u_domctl)
-{
-    return -ENOSYS;
-}
-
-static inline void vm_event_vcpu_pause(struct vcpu *v) {}
-static inline void vm_event_vcpu_unpause(struct vcpu *v) {}
-
-#endif /* HAS_MEM_ACCESS */
-
 #endif /* __VM_EVENT_H__ */
 
 
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index 4227093..50ee929 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -513,7 +513,6 @@ static XSM_INLINE int xsm_hvm_param_nested(XSM_DEFAULT_ARG struct domain *d)
     return xsm_default_action(action, current->domain, d);
 }
 
-#ifdef HAS_MEM_ACCESS
 static XSM_INLINE int xsm_vm_event_control(XSM_DEFAULT_ARG struct domain *d, int mode, int op)
 {
     XSM_ASSERT_ACTION(XSM_PRIV);
@@ -525,7 +524,6 @@ static XSM_INLINE int xsm_vm_event_op(XSM_DEFAULT_ARG struct domain *d, int op)
     XSM_ASSERT_ACTION(XSM_DM_PRIV);
     return xsm_default_action(action, current->domain, d);
 }
-#endif
 
 #ifdef CONFIG_X86
 static XSM_INLINE int xsm_do_mca(XSM_DEFAULT_VOID)
diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
index cff9d35..d56a68f 100644
--- a/xen/include/xsm/xsm.h
+++ b/xen/include/xsm/xsm.h
@@ -141,10 +141,8 @@ struct xsm_operations {
     int (*hvm_param_nested) (struct domain *d);
     int (*get_vnumainfo) (struct domain *d);
 
-#ifdef HAS_MEM_ACCESS
     int (*vm_event_control) (struct domain *d, int mode, int op);
     int (*vm_event_op) (struct domain *d, int op);
-#endif
 
 #ifdef CONFIG_X86
     int (*do_mca) (void);
@@ -543,7 +541,6 @@ static inline int xsm_get_vnumainfo (xsm_default_t def, struct domain *d)
     return xsm_ops->get_vnumainfo(d);
 }
 
-#ifdef HAS_MEM_ACCESS
 static inline int xsm_vm_event_control (xsm_default_t def, struct domain *d, int mode, int op)
 {
     return xsm_ops->vm_event_control(d, mode, op);
@@ -553,7 +550,6 @@ static inline int xsm_vm_event_op (xsm_default_t def, struct domain *d, int op)
 {
     return xsm_ops->vm_event_op(d, op);
 }
-#endif
 
 #ifdef CONFIG_X86
 static inline int xsm_do_mca(xsm_default_t def)
diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
index 25fca68..6d12d32 100644
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -118,10 +118,8 @@ void xsm_fixup_ops (struct xsm_operations *ops)
     set_to_dummy_if_null(ops, remove_from_physmap);
     set_to_dummy_if_null(ops, map_gmfn_foreign);
 
-#ifdef HAS_MEM_ACCESS
     set_to_dummy_if_null(ops, vm_event_control);
     set_to_dummy_if_null(ops, vm_event_op);
-#endif
 
 #ifdef CONFIG_X86
     set_to_dummy_if_null(ops, do_mca);
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index c419543..5008b79 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -577,9 +577,7 @@ static int flask_domctl(struct domain *d, int cmd)
     case XEN_DOMCTL_iomem_permission:
     case XEN_DOMCTL_memory_mapping:
     case XEN_DOMCTL_set_target:
-#ifdef HAS_MEM_ACCESS
     case XEN_DOMCTL_vm_event_op:
-#endif
 #ifdef CONFIG_X86
     /* These have individual XSM hooks (arch/x86/domctl.c) */
     case XEN_DOMCTL_shadow_op:
@@ -1136,6 +1134,16 @@ static int flask_hvm_param_nested(struct domain *d)
     return current_has_perm(d, SECCLASS_HVM, HVM__NESTED);
 }
 
+static int flask_vm_event_control(struct domain *d, int mode, int op)
+{
+    return current_has_perm(d, SECCLASS_HVM, HVM__VM_EVENT);
+}
+
+static int flask_vm_event_op(struct domain *d, int op)
+{
+    return current_has_perm(d, SECCLASS_HVM, HVM__VM_EVENT);
+}
+
 #if defined(HAS_PASSTHROUGH) && defined(HAS_PCI)
 static int flask_get_device_group(uint32_t machine_bdf)
 {
@@ -1202,18 +1210,6 @@ static int flask_deassign_device(struct domain *d, uint32_t machine_bdf)
 }
 #endif /* HAS_PASSTHROUGH && HAS_PCI */
 
-#ifdef HAS_MEM_ACCESS
-static int flask_vm_event_control(struct domain *d, int mode, int op)
-{
-    return current_has_perm(d, SECCLASS_HVM, HVM__VM_EVENT);
-}
-
-static int flask_vm_event_op(struct domain *d, int op)
-{
-    return current_has_perm(d, SECCLASS_HVM, HVM__VM_EVENT);
-}
-#endif /* HAS_MEM_ACCESS */
-
 #ifdef CONFIG_X86
 static int flask_do_mca(void)
 {
@@ -1581,6 +1577,9 @@ static struct xsm_operations flask_ops = {
     .do_xsm_op = do_flask_op,
     .get_vnumainfo = flask_get_vnumainfo,
 
+    .vm_event_control = flask_vm_event_control,
+    .vm_event_op = flask_vm_event_op,
+
 #ifdef CONFIG_COMPAT
     .do_compat_op = compat_flask_op,
 #endif
@@ -1596,11 +1595,6 @@ static struct xsm_operations flask_ops = {
     .deassign_device = flask_deassign_device,
 #endif
 
-#ifdef HAS_MEM_ACCESS
-    .vm_event_control = flask_vm_event_control,
-    .vm_event_op = flask_vm_event_op,
-#endif
-
 #ifdef CONFIG_X86
     .do_mca = flask_do_mca,
     .shadow_control = flask_shadow_control,
-- 
2.1.4