[Xen-devel] [PATCH 1/2 for-4.12] xen: introduce VCPUOP_register_runstate_phys_memory_area hypercall

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

From: Andrii Anisov <andrii_anisov@xxxxxxxx>

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@xxxxxxxx>
---
 xen/arch/arm/domain.c     | 39 ++++++++++++++++++---------------
 xen/arch/x86/domain.c     | 55 ++++++++++++++++++++++++++---------------------
 xen/common/domain.c       |  7 ++++++
 xen/include/public/vcpu.h | 16 ++++++++++++++
 xen/include/xen/sched.h   |  7 ++++++
 5 files changed, 83 insertions(+), 41 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 6dc633e..ec9bdbd 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -277,29 +277,33 @@ static void ctxt_switch_to(struct vcpu *n)
 /* Update per-VCPU guest runstate shared memory area (if registered). */
 static void update_runstate_area(struct vcpu *v)
 {
-    void __user *guest_handle = NULL;
-
     if ( guest_handle_is_null(runstate_guest(v)) )
         return;
 
-    if ( VM_ASSIST(v->domain, runstate_update_flag) )
+    if ( v->runstate_guest_type == RUNSTATE_VADDR )
     {
-        guest_handle = &v->runstate_guest.p->state_entry_time + 1;
-        guest_handle--;
-        v->runstate.state_entry_time |= XEN_RUNSTATE_UPDATE;
-        __raw_copy_to_guest(guest_handle,
-                            (void *)(&v->runstate.state_entry_time + 1) - 1, 
1);
-        smp_wmb();
-    }
+        void __user *guest_handle = NULL;
+        if ( VM_ASSIST(v->domain, runstate_update_flag) )
+        {
+            guest_handle = &v->runstate_guest.p->state_entry_time + 1;
+            guest_handle--;
+            v->runstate.state_entry_time |= XEN_RUNSTATE_UPDATE;
+            __raw_copy_to_guest(guest_handle,
+                                (void *)(&v->runstate.state_entry_time + 1) - 
1,
+                                1);
+            smp_wmb();
+        }
 
-    __copy_to_guest(runstate_guest(v), &v->runstate, 1);
+        __copy_to_guest(runstate_guest(v), &v->runstate, 1);
 
-    if ( guest_handle )
-    {
-        v->runstate.state_entry_time &= ~XEN_RUNSTATE_UPDATE;
-        smp_wmb();
-        __raw_copy_to_guest(guest_handle,
-                            (void *)(&v->runstate.state_entry_time + 1) - 1, 
1);
+        if ( guest_handle )
+        {
+            v->runstate.state_entry_time &= ~XEN_RUNSTATE_UPDATE;
+            smp_wmb();
+            __raw_copy_to_guest(guest_handle,
+                                (void *)(&v->runstate.state_entry_time + 1) - 
1,
+                                1);
+        }
     }
 }
 
@@ -998,6 +1002,7 @@ long do_arm_vcpu_op(int cmd, unsigned int vcpuid, 
XEN_GUEST_HANDLE_PARAM(void) a
     {
         case VCPUOP_register_vcpu_info:
         case VCPUOP_register_runstate_memory_area:
+        case VCPUOP_register_runstate_phys_memory_area:
             return do_vcpu_op(cmd, vcpuid, arg);
         default:
             return -EINVAL;
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index b5febd6..2acffba 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1614,36 +1614,43 @@ bool update_runstate_area(struct vcpu *v)
 
     update_guest_memory_policy(v, &policy);
 
-    if ( VM_ASSIST(v->domain, runstate_update_flag) )
+    if ( v->runstate_guest_type == RUNSTATE_VADDR )
     {
-        guest_handle = has_32bit_shinfo(v->domain)
-            ? &v->runstate_guest.compat.p->state_entry_time + 1
-            : &v->runstate_guest.native.p->state_entry_time + 1;
-        guest_handle--;
-        v->runstate.state_entry_time |= XEN_RUNSTATE_UPDATE;
-        __raw_copy_to_guest(guest_handle,
-                            (void *)(&v->runstate.state_entry_time + 1) - 1, 
1);
-        smp_wmb();
-    }
+        if ( VM_ASSIST(v->domain, runstate_update_flag) )
+        {
+            guest_handle = has_32bit_shinfo(v->domain)
+                ? &v->runstate_guest.compat.p->state_entry_time + 1
+                : &v->runstate_guest.native.p->state_entry_time + 1;
+            guest_handle--;
+            v->runstate.state_entry_time |= XEN_RUNSTATE_UPDATE;
+            __raw_copy_to_guest(guest_handle,
+                                (void *)(&v->runstate.state_entry_time + 1) - 
1, 1);
+            smp_wmb();
+        }
 
-    if ( has_32bit_shinfo(v->domain) )
-    {
-        struct compat_vcpu_runstate_info info;
+        if ( has_32bit_shinfo(v->domain) )
+        {
+            struct compat_vcpu_runstate_info info;
 
-        XLAT_vcpu_runstate_info(&info, &v->runstate);
-        __copy_to_guest(v->runstate_guest.compat, &info, 1);
-        rc = true;
+            XLAT_vcpu_runstate_info(&info, &v->runstate);
+            __copy_to_guest(v->runstate_guest.compat, &info, 1);
+            rc = true;
+        }
+        else
+            rc = __copy_to_guest(runstate_guest(v), &v->runstate, 1) !=
+                 sizeof(v->runstate);
+
+        if ( guest_handle )
+        {
+            v->runstate.state_entry_time &= ~XEN_RUNSTATE_UPDATE;
+            smp_wmb();
+            __raw_copy_to_guest(guest_handle,
+                                (void *)(&v->runstate.state_entry_time + 1) - 
1, 1);
+        }
     }
     else
-        rc = __copy_to_guest(runstate_guest(v), &v->runstate, 1) !=
-             sizeof(v->runstate);
-
-    if ( guest_handle )
     {
-        v->runstate.state_entry_time &= ~XEN_RUNSTATE_UPDATE;
-        smp_wmb();
-        __raw_copy_to_guest(guest_handle,
-                            (void *)(&v->runstate.state_entry_time + 1) - 1, 
1);
+        rc = true;
     }
 
     update_guest_memory_policy(v, &policy);
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 32bca8d..2c83ede 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -1521,6 +1521,7 @@ long do_vcpu_op(int cmd, unsigned int vcpuid, 
XEN_GUEST_HANDLE_PARAM(void) arg)
 
         rc = 0;
         runstate_guest(v) = area.addr.h;
+        v->runstate_guest_type = RUNSTATE_VADDR;
 
         if ( v == current )
         {
@@ -1535,6 +1536,12 @@ long do_vcpu_op(int cmd, unsigned int vcpuid, 
XEN_GUEST_HANDLE_PARAM(void) arg)
         break;
     }
 
+    case VCPUOP_register_runstate_phys_memory_area:
+    {
+        rc = -ENOSYS;
+        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..0722892 100644
--- a/xen/include/public/vcpu.h
+++ b/xen/include/public/vcpu.h
@@ -235,6 +235,22 @@ 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__ */
 
 /*
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index edee52d..9ea76ec 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -163,6 +163,13 @@ struct vcpu
     void            *sched_priv;    /* scheduler-specific data */
 
     struct vcpu_runstate_info runstate;
+
+    enum {
+        RUNSTATE_NONE = 0,
+        RUNSTATE_PADDR = 1,
+        RUNSTATE_VADDR = 2,
+    } runstate_guest_type;
+
 #ifndef CONFIG_COMPAT
 # define runstate_guest(v) ((v)->runstate_guest)
     XEN_GUEST_HANDLE(vcpu_runstate_info_t) runstate_guest; /* guest address */
-- 
2.7.4


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