Since we already require at least kernel 3.15 in the s390x KVM code,
we can assume that the KVM_CAP_SYNC_REGS capability is always there.
Thus turn this into a hard requirement now.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 target/s390x/kvm/kvm.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index bc5c56a305..b3e2eaa2eb 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -337,21 +337,29 @@ int kvm_arch_get_default_type(MachineState *ms)
 
 int kvm_arch_init(MachineState *ms, KVMState *s)
 {
+    int required_caps[] = {
+        KVM_CAP_DEVICE_CTRL,
+        KVM_CAP_SYNC_REGS,
+    };
+
+    for (int i = 0; i < ARRAY_SIZE(required_caps); i++) {
+        if (!kvm_check_extension(s, required_caps[i])) {
+            error_report("KVM is missing capability #%d - "
+                         "please use kernel 3.15 or newer", required_caps[i]);
+            return -1;
+        }
+    }
+
     object_class_foreach(ccw_machine_class_foreach, TYPE_S390_CCW_MACHINE,
                          false, NULL);
 
-    if (!kvm_check_extension(kvm_state, KVM_CAP_DEVICE_CTRL)) {
-        error_report("KVM is missing capability KVM_CAP_DEVICE_CTRL - "
-                     "please use kernel 3.15 or newer");
-        return -1;
-    }
     if (!kvm_check_extension(s, KVM_CAP_S390_COW)) {
         error_report("KVM is missing capability KVM_CAP_S390_COW - "
                      "unsupported environment");
         return -1;
     }
 
-    cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS);
+    cap_sync_regs = true;
     cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF);
     cap_mem_op = kvm_check_extension(s, KVM_CAP_S390_MEM_OP);
     cap_mem_op_extension = kvm_check_extension(s, KVM_CAP_S390_MEM_OP_EXTENSION);
-- 
2.41.0

Am 09.10.23 um 19:07 schrieb Thomas Huth:
> Since we already require at least kernel 3.15 in the s390x KVM code,
> we can assume that the KVM_CAP_SYNC_REGS capability is always there.
> Thus turn this into a hard requirement now.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>   target/s390x/kvm/kvm.c | 20 ++++++++++++++------
>   1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
> index bc5c56a305..b3e2eaa2eb 100644
> --- a/target/s390x/kvm/kvm.c
> +++ b/target/s390x/kvm/kvm.c
> @@ -337,21 +337,29 @@ int kvm_arch_get_default_type(MachineState *ms)
>   
>   int kvm_arch_init(MachineState *ms, KVMState *s)
>   {
> +    int required_caps[] = {
> +        KVM_CAP_DEVICE_CTRL,
> +        KVM_CAP_SYNC_REGS,
> +    };
> +
> +    for (int i = 0; i < ARRAY_SIZE(required_caps); i++) {
> +        if (!kvm_check_extension(s, required_caps[i])) {
> +            error_report("KVM is missing capability #%d - "
> +                         "please use kernel 3.15 or newer", required_caps[i]);
> +            return -1;
> +        }
> +    }
> +
>       object_class_foreach(ccw_machine_class_foreach, TYPE_S390_CCW_MACHINE,
>                            false, NULL);
>   
> -    if (!kvm_check_extension(kvm_state, KVM_CAP_DEVICE_CTRL)) {
> -        error_report("KVM is missing capability KVM_CAP_DEVICE_CTRL - "
> -                     "please use kernel 3.15 or newer");
> -        return -1;
> -    }
>       if (!kvm_check_extension(s, KVM_CAP_S390_COW)) {
>           error_report("KVM is missing capability KVM_CAP_S390_COW - "
>                        "unsupported environment");
>           return -1;
>       }

Not sure if we also want to move KVM_CAP_S390_COW somehow. The message would be different.
Aparch from that:
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>


>   
> -    cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS);
> +    cap_sync_regs = true;
>       cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF);
>       cap_mem_op = kvm_check_extension(s, KVM_CAP_S390_MEM_OP);
>       cap_mem_op_extension = kvm_check_extension(s, KVM_CAP_S390_MEM_OP_EXTENSION);