[PATCH v5 09/18] target/arm/kvm: Introduce kvm_get_writable_id_regs

[Eric Auger <eric.auger@redhat.com>]

From: Cornelia Huck <cohuck@redhat.com>

Add an helper to retrieve the writable id reg bitmask.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

---

v4 -> v5:
- get rid of IdRegMap datatype
- do not store the status of the query in cpu anymore, just
  return the error in case the retrieval failed
- add implementation in kvm-stub.c
---
 target/arm/kvm-stub.c |  5 +++++
 target/arm/kvm.c      | 21 +++++++++++++++++++++
 target/arm/kvm_arm.h  |  2 ++
 3 files changed, 28 insertions(+)

diff --git a/target/arm/kvm-stub.c b/target/arm/kvm-stub.c
index 88cbe8d85c..cd88eb741a 100644
--- a/target/arm/kvm-stub.c
+++ b/target/arm/kvm-stub.c
@@ -119,3 +119,8 @@ char *kvm_print_register_name(uint64_t regidx)
 {
     g_assert_not_reached();
 }
+
+int kvm_arm_get_writable_id_regs(uint64_t *idregmap)
+{
+    g_assert_not_reached();
+}
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 7d194ea112..4adfd20050 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -505,6 +505,27 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
     env->features = arm_host_cpu_features.features;
 }
 
+int kvm_arm_get_writable_id_regs(uint64_t *idregmap)
+{
+    int cap_writable_id_regs;
+    struct reg_mask_range range = {
+        .range = 0, /* up to now only a single range is supported */
+        .addr = (uint64_t)idregmap,
+    };
+    int ret;
+
+    cap_writable_id_regs =
+        kvm_check_extension(kvm_state, KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES);
+
+    if (!cap_writable_id_regs ||
+        !(cap_writable_id_regs & (1 << KVM_ARM_FEATURE_ID_RANGE))) {
+        return -ENOSYS;
+    }
+
+    ret = kvm_vm_ioctl(kvm_state, KVM_ARM_GET_REG_WRITABLE_MASKS, &range);
+    return ret;
+}
+
 static bool kvm_no_adjvtime_get(Object *obj, Error **errp)
 {
     return !ARM_CPU(obj)->kvm_adjvtime;
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index e7c40fb003..c1c2e7ec37 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -240,4 +240,6 @@ void arm_gic_cap_kvm_probe(GICCapability *v2, GICCapability *v3);
  */
 char *kvm_print_register_name(uint64_t regidx);
 
+int kvm_arm_get_writable_id_regs(uint64_t *idregmap);
+
 #endif
-- 
2.53.0