s390x/kvm: Configure page size after memory has actually been initialized

Right now we configure the pagesize quite early, when initializing KVM.
This is long before system memory is actually allocated via
memory_region_allocate_system_memory(), and therefore memory backends
marked as mapped.

Instead, let's configure the maximum page size after initializing
memory in s390_memory_init(). cap_hpage_1m is still properly
configured before creating any CPUs, and therefore before configuring
the CPU model and eventually enabling CMMA.

This is not a fix but rather a preparation for the future, when initial
memory might reside on memory backends (not the case for s390x right now)
We will replace qemu_getrampagesize() soon by a function that will always
return the maximum page size (not the minimum page size, which only
works by pure luck so far, as there are no memory backends).

Acked-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190417113143.5551-2-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

1 files changed, 14 insertions, 21 deletions

diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 2c6e35b5aa..7df7be4a1b 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -283,44 +283,37 @@ void kvm_s390_crypto_reset(void)
     }
 }
 
-static int kvm_s390_configure_mempath_backing(KVMState *s)
+void kvm_s390_set_max_pagesize(uint64_t pagesize, Error **errp)
 {
-    size_t path_psize = qemu_getrampagesize();
-
-    if (path_psize == 4 * KiB) {
-        return 0;
+    if (pagesize == 4 * KiB) {
+        return;
     }
 
     if (!hpage_1m_allowed()) {
-        error_report("This QEMU machine does not support huge page "
-                     "mappings");
-        return -EINVAL;
+        error_setg(errp, "This QEMU machine does not support huge page "
+                   "mappings");
+        return;
     }
 
-    if (path_psize != 1 * MiB) {
-        error_report("Memory backing with 2G pages was specified, "
-                     "but KVM does not support this memory backing");
-        return -EINVAL;
+    if (pagesize != 1 * MiB) {
+        error_setg(errp, "Memory backing with 2G pages was specified, "
+                   "but KVM does not support this memory backing");
+        return;
     }
 
-    if (kvm_vm_enable_cap(s, KVM_CAP_S390_HPAGE_1M, 0)) {
-        error_report("Memory backing with 1M pages was specified, "
-                     "but KVM does not support this memory backing");
-        return -EINVAL;
+    if (kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_HPAGE_1M, 0)) {
+        error_setg(errp, "Memory backing with 1M pages was specified, "
+                   "but KVM does not support this memory backing");
+        return;
     }
 
     cap_hpage_1m = 1;
-    return 0;
 }
 
 int kvm_arch_init(MachineState *ms, KVMState *s)
 {
     MachineClass *mc = MACHINE_GET_CLASS(ms);
 
-    if (kvm_s390_configure_mempath_backing(s)) {
-        return -EINVAL;
-    }
-
     mc->default_cpu_type = S390_CPU_TYPE_NAME("host");
     cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS);
     cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF);