[RFC PATCH v3 20/38] i386/xen: handle VCPUOP_register_runstate_memory_area

[David Woodhouse <dwmw2@infradead.org>]

From: Joao Martins <joao.m.martins@oracle.com>

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>
---
 target/i386/cpu.h         |  1 +
 target/i386/kvm/kvm.c     |  9 +++++++++
 target/i386/kvm/xen-emu.c | 42 +++++++++++++++++++++++++++++++++++++++
 target/i386/machine.c     |  4 +++-
 4 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 96c2d0d5cb..bf44a87ddb 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1791,6 +1791,7 @@ 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;
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 766e0add13..8aee95d4c1 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1805,6 +1805,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
     env->xen_vcpu_info_gpa = UINT64_MAX;
     env->xen_vcpu_info_default_gpa = UINT64_MAX;
     env->xen_vcpu_time_info_gpa = UINT64_MAX;
+    env->xen_vcpu_runstate_gpa = UINT64_MAX;
 
     if (cs->kvm_state->xen_version) {
 #ifdef CONFIG_XEN_EMU
@@ -4748,6 +4749,14 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
                 return ret;
             }
         }
+
+        gpa = x86_cpu->env.xen_vcpu_runstate_gpa;
+        if (gpa != UINT64_MAX) {
+            ret = kvm_xen_set_vcpu_attr(cpu, KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR, gpa);
+            if (ret < 0) {
+                return ret;
+            }
+        }
     }
 #endif
 
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index b45d5af7d7..1297b37ee8 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -208,6 +208,17 @@ 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 int xen_set_shared_info(uint64_t gfn)
 {
     uint64_t gpa = gfn << TARGET_PAGE_BITS;
@@ -448,6 +459,34 @@ 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)
 {
@@ -456,6 +495,9 @@ 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;
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 9acef102a3..6a510e5cbd 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -1264,7 +1264,8 @@ static bool xen_vcpu_needed(void *opaque)
 
     return (env->xen_vcpu_info_gpa != UINT64_MAX ||
             env->xen_vcpu_info_default_gpa != UINT64_MAX ||
-            env->xen_vcpu_time_info_gpa != UINT64_MAX);
+            env->xen_vcpu_time_info_gpa != UINT64_MAX ||
+            env->xen_vcpu_runstate_gpa != UINT64_MAX);
 }
 
 static const VMStateDescription vmstate_xen_vcpu = {
@@ -1276,6 +1277,7 @@ 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()
     }
 };
-- 
2.35.3