[PATCH v4 3/3] xen: mem_access: conditionally compile vm_event.c & monitor.c

[Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxx>

Extend coverage of CONFIG_VM_EVENT option and make the build of VM events
and monitoring support optional. Also make MEM_PAGING option depend on VM_EVENT
to document that mem_paging is relying on vm_event.
This is to reduce code size on Arm when this option isn't enabled.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
Reviewed-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
---
changes in v4:
 - vm_event_domctl stub returns -EOPNOTSUPP
changes in v3:
 - add dependency MEM_PAGING -> VM_EVENT
 - monitor_domctl() stub returns -EOPNOTSUPP
changes in v2:
 - rename CONFIG_MEM_ACCESS -> CONFIG_VM_EVENT
 - tags
---
 xen/arch/arm/Makefile      |  4 ++--
 xen/arch/arm/vsmc.c        |  3 ++-
 xen/arch/x86/Kconfig       |  2 +-
 xen/common/Makefile        |  4 ++--
 xen/include/xen/monitor.h  |  9 +++++++++
 xen/include/xen/vm_event.h | 14 +++++++++++---
 6 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 3bd5125e64..4837ad467a 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -40,7 +40,7 @@ obj-$(CONFIG_LIVEPATCH) += livepatch.o
 obj-$(CONFIG_LLC_COLORING) += llc-coloring.o
 obj-$(CONFIG_VM_EVENT) += mem_access.o
 obj-y += mm.o
-obj-y += monitor.o
+obj-$(CONFIG_VM_EVENT) += monitor.o
 obj-y += p2m.o
 obj-y += platform.o
 obj-y += platform_hypercall.o
@@ -66,7 +66,7 @@ obj-$(CONFIG_VGICV2) += vgic-v2.o
 obj-$(CONFIG_GICV3) += vgic-v3.o
 obj-$(CONFIG_HAS_ITS) += vgic-v3-its.o
 endif
-obj-y += vm_event.o
+obj-$(CONFIG_VM_EVENT) += vm_event.o
 obj-y += vtimer.o
 obj-$(CONFIG_SBSA_VUART_CONSOLE) += vpl011.o
 obj-y += vsmc.o
diff --git a/xen/arch/arm/vsmc.c b/xen/arch/arm/vsmc.c
index e253865b6c..6081f14ed0 100644
--- a/xen/arch/arm/vsmc.c
+++ b/xen/arch/arm/vsmc.c
@@ -330,7 +330,8 @@ void do_trap_smc(struct cpu_user_regs *regs, const union 
hsr hsr)
     }
 
     /* If monitor is enabled, let it handle the call. */
-    if ( current->domain->arch.monitor.privileged_call_enabled )
+    if ( IS_ENABLED(CONFIG_VM_EVENT) &&
+         current->domain->arch.monitor.privileged_call_enabled )
         rc = monitor_smc();
 
     if ( rc == 1 )
diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index 6e41bc0fb4..f086799594 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -350,7 +350,7 @@ endif
 
 config MEM_PAGING
        bool "Xen memory paging support (UNSUPPORTED)" if UNSUPPORTED
-       depends on HVM
+       depends on HVM && VM_EVENT
 
 config MEM_SHARING
        bool "Xen memory sharing support (UNSUPPORTED)" if UNSUPPORTED
diff --git a/xen/common/Makefile b/xen/common/Makefile
index b71d4b3efa..ac23120d7d 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -54,7 +54,7 @@ obj-y += timer.o
 obj-$(CONFIG_TRACEBUFFER) += trace.o
 obj-y += version.o
 obj-y += virtual_region.o
-obj-y += vm_event.o
+obj-$(CONFIG_VM_EVENT) += vm_event.o
 obj-$(CONFIG_HAS_VMAP) += vmap.o
 obj-y += vsprintf.o
 obj-y += wait.o
@@ -68,7 +68,7 @@ obj-$(CONFIG_COMPAT) += $(addprefix compat/,domain.o memory.o 
multicall.o xlat.o
 
 ifneq ($(CONFIG_PV_SHIM_EXCLUSIVE),y)
 obj-y += domctl.o
-obj-y += monitor.o
+obj-$(CONFIG_VM_EVENT) += monitor.o
 obj-y += sysctl.o
 endif
 
diff --git a/xen/include/xen/monitor.h b/xen/include/xen/monitor.h
index 713d54f7c1..634b6cd2a1 100644
--- a/xen/include/xen/monitor.h
+++ b/xen/include/xen/monitor.h
@@ -27,8 +27,17 @@
 struct domain;
 struct xen_domctl_monitor_op;
 
+#ifdef CONFIG_VM_EVENT
 int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop);
 void monitor_guest_request(void);
+#else
+static inline int monitor_domctl(struct domain *d,
+                                 struct xen_domctl_monitor_op *mop)
+{
+    return -EOPNOTSUPP;
+}
+static inline void monitor_guest_request(void) {}
+#endif
 
 int monitor_traps(struct vcpu *v, bool sync, vm_event_request_t *req);
 
diff --git a/xen/include/xen/vm_event.h b/xen/include/xen/vm_event.h
index 9a86358b42..c4535b6c61 100644
--- a/xen/include/xen/vm_event.h
+++ b/xen/include/xen/vm_event.h
@@ -50,9 +50,6 @@ struct vm_event_domain
     unsigned int last_vcpu_wake_up;
 };
 
-/* Clean up on domain destruction */
-void vm_event_cleanup(struct domain *d);
-
 /* Returns whether a ring has been set up */
 bool vm_event_check_ring(struct vm_event_domain *ved);
 
@@ -88,7 +85,18 @@ void vm_event_cancel_slot(struct domain *d, struct 
vm_event_domain *ved);
 void vm_event_put_request(struct domain *d, struct vm_event_domain *ved,
                           vm_event_request_t *req);
 
+#ifdef CONFIG_VM_EVENT
+/* Clean up on domain destruction */
+void vm_event_cleanup(struct domain *d);
 int vm_event_domctl(struct domain *d, struct xen_domctl_vm_event_op *vec);
+#else
+static inline void vm_event_cleanup(struct domain *d) {}
+static inline int vm_event_domctl(struct domain *d,
+                                  struct xen_domctl_vm_event_op *vec)
+{
+    return -EOPNOTSUPP;
+}
+#endif
 
 void vm_event_vcpu_pause(struct vcpu *v);
 void vm_event_vcpu_unpause(struct vcpu *v);
-- 
2.25.1