i386/xen: handle VCPUOP_register_runstate_memory_area

Allow guest to setup the vcpu runstates which is used as
steal clock.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>

target/i386/cpu.h

@@ -1802,6 +1802,7 @@ typedef struct CPUArchState {
     uint64_t xen_vcpu_info_gpa;
     uint64_t xen_vcpu_info_default_gpa;
     uint64_t xen_vcpu_time_info_gpa;
+    uint64_t xen_vcpu_runstate_gpa;
 #endif
 #if defined(CONFIG_HVF)
     HVFX86LazyFlags hvf_lflags;

target/i386/kvm/xen-emu.c

@@ -160,6 +160,7 @@ int kvm_xen_init_vcpu(CPUState *cs)
     env->xen_vcpu_info_gpa = INVALID_GPA;
     env->xen_vcpu_info_default_gpa = INVALID_GPA;
     env->xen_vcpu_time_info_gpa = INVALID_GPA;
+    env->xen_vcpu_runstate_gpa = INVALID_GPA;
 
     return 0;
 }
@@ -254,6 +255,17 @@ static void do_set_vcpu_time_info_gpa(CPUState *cs, run_on_cpu_data data)
                           env->xen_vcpu_time_info_gpa);
 }
 
+static void do_set_vcpu_runstate_gpa(CPUState *cs, run_on_cpu_data data)
+{
+    X86CPU *cpu = X86_CPU(cs);
+    CPUX86State *env = &cpu->env;
+
+    env->xen_vcpu_runstate_gpa = data.host_ulong;
+
+    kvm_xen_set_vcpu_attr(cs, KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR,
+                          env->xen_vcpu_runstate_gpa);
+}
+
 static void do_vcpu_soft_reset(CPUState *cs, run_on_cpu_data data)
 {
     X86CPU *cpu = X86_CPU(cs);
@@ -262,10 +274,14 @@ static void do_vcpu_soft_reset(CPUState *cs, run_on_cpu_data data)
     env->xen_vcpu_info_gpa = INVALID_GPA;
     env->xen_vcpu_info_default_gpa = INVALID_GPA;
     env->xen_vcpu_time_info_gpa = INVALID_GPA;
+    env->xen_vcpu_runstate_gpa = INVALID_GPA;
 
     kvm_xen_set_vcpu_attr(cs, KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO, INVALID_GPA);
     kvm_xen_set_vcpu_attr(cs, KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO,
                           INVALID_GPA);
+    kvm_xen_set_vcpu_attr(cs, KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR,
+                          INVALID_GPA);
+
 }
 
 static int xen_set_shared_info(uint64_t gfn)
@@ -517,6 +533,35 @@ static int vcpuop_register_vcpu_time_info(CPUState *cs, CPUState *target,
     return 0;
 }
 
+static int vcpuop_register_runstate_info(CPUState *cs, CPUState *target,
+                                         uint64_t arg)
+{
+    struct vcpu_register_runstate_memory_area rma;
+    uint64_t gpa;
+    size_t len;
+
+    /* No need for 32/64 compat handling */
+    qemu_build_assert(sizeof(rma) == 8);
+    /* The runstate area actually does change size, but Linux copes. */
+
+    if (!target) {
+        return -ENOENT;
+    }
+
+    if (kvm_copy_from_gva(cs, arg, &rma, sizeof(rma))) {
+        return -EFAULT;
+    }
+
+    /* As with vcpu_time_info, Xen actually uses the GVA but KVM doesn't. */
+    if (!kvm_gva_to_gpa(cs, rma.addr.p, &gpa, &len, false)) {
+        return -EFAULT;
+    }
+
+    async_run_on_cpu(target, do_set_vcpu_runstate_gpa,
+                     RUN_ON_CPU_HOST_ULONG(gpa));
+    return 0;
+}
+
 static bool kvm_xen_hcall_vcpu_op(struct kvm_xen_exit *exit, X86CPU *cpu,
                                   int cmd, int vcpu_id, uint64_t arg)
 {
@@ -525,6 +570,9 @@ static bool kvm_xen_hcall_vcpu_op(struct kvm_xen_exit *exit, X86CPU *cpu,
     int err;
 
     switch (cmd) {
+    case VCPUOP_register_runstate_memory_area:
+        err = vcpuop_register_runstate_info(cs, dest, arg);
+        break;
     case VCPUOP_register_vcpu_time_memory_area:
         err = vcpuop_register_vcpu_time_info(cs, dest, arg);
         break;
@@ -730,6 +778,15 @@ int kvm_put_xen_state(CPUState *cs)
         }
     }
 
+    gpa = env->xen_vcpu_runstate_gpa;
+    if (gpa != INVALID_GPA) {
+        ret = kvm_xen_set_vcpu_attr(cs, KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR,
+                                    gpa);
+        if (ret < 0) {
+            return ret;
+        }
+    }
+
     return 0;
 }
 

target/i386/machine.c

@@ -1273,6 +1273,7 @@ static const VMStateDescription vmstate_xen_vcpu = {
         VMSTATE_UINT64(env.xen_vcpu_info_gpa, X86CPU),
         VMSTATE_UINT64(env.xen_vcpu_info_default_gpa, X86CPU),
         VMSTATE_UINT64(env.xen_vcpu_time_info_gpa, X86CPU),
+        VMSTATE_UINT64(env.xen_vcpu_runstate_gpa, X86CPU),
         VMSTATE_END_OF_LIST()
     }
 };