[PATCH v2 1/2] xen: introduce VCPUOP_register_runstate_phys_memory_area hypercall

[Andrii Anisov <andrii.anisov@gmail.com>]

From: Andrii Anisov <andrii_anisov@epam.com>

The hypercall employs the same vcpu_register_runstate_memory_area
structure for the interface, but requires registered area to not
cross a page boundary.

Signed-off-by: Andrii Anisov <andrii_anisov@epam.com>
---
 xen/common/domain.c       |  5 ++++-
 xen/include/public/vcpu.h | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 88bbe98..ae22049 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -1532,10 +1532,13 @@ long do_vcpu_op(int cmd, unsigned int vcpuid, XEN_GUEST_HANDLE_PARAM(void) arg)
             vcpu_runstate_get(v, &runstate);
             __copy_to_guest(runstate_guest(v), &runstate, 1);
         }
-
         break;
     }
 
+    case VCPUOP_register_runstate_phys_memory_area:
+        rc = -EOPNOTSUPP;
+        break;
+
 #ifdef VCPU_TRAP_NMI
     case VCPUOP_send_nmi:
         if ( !guest_handle_is_null(arg) )
diff --git a/xen/include/public/vcpu.h b/xen/include/public/vcpu.h
index 3623af9..d7da4a3 100644
--- a/xen/include/public/vcpu.h
+++ b/xen/include/public/vcpu.h
@@ -235,6 +235,21 @@ struct vcpu_register_time_memory_area {
 typedef struct vcpu_register_time_memory_area vcpu_register_time_memory_area_t;
 DEFINE_XEN_GUEST_HANDLE(vcpu_register_time_memory_area_t);
 
+/*
+ * Register a shared memory area from which the guest may obtain its own
+ * runstate information without needing to execute a hypercall.
+ * Notes:
+ *  1. The registered address must be guest's physical address.
+ *  2. The registered runstate area should not cross page boundary.
+ *  3. Only one shared area may be registered per VCPU. The shared area is
+ *     updated by the hypervisor each time the VCPU is scheduled. Thus
+ *     runstate.state will always be RUNSTATE_running and
+ *     runstate.state_entry_time will indicate the system time at which the
+ *     VCPU was last scheduled to run.
+ * @extra_arg == pointer to vcpu_register_runstate_memory_area structure.
+ */
+#define VCPUOP_register_runstate_phys_memory_area 14
+
 #endif /* __XEN_PUBLIC_VCPU_H__ */
 
 /*
-- 
2.7.4


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