[PATCH] kvm: Fix crash by initializing kvm_state early

[Gavin Shan <gshan@redhat.com>]

Runs into core dump on arm64 and the backtrace extracted from the
core dump is shown as below. It's caused by accessing @kvm_state which
isn't initialized at that point due to commit 176d073029 ("hw/arm/virt:
Use machine_memory_devices_init()"), where the machine's memory region
is added ealier than before.

    main
    qemu_init
    configure_accelerators
    qemu_opts_foreach
    do_configure_accelerator
    accel_init_machine
    kvm_init
    virt_kvm_type
    virt_set_memmap
    machine_memory_devices_init
    memory_region_add_subregion
    memory_region_add_subregion_common
    memory_region_update_container_subregions
    memory_region_transaction_begin
    qemu_flush_coalesced_mmio_buffer
    kvm_flush_coalesced_mmio_buffer

Fix it by initializing @kvm_state early. With this applied, no crash
is observed on arm64.

Fixes: 176d073029 ("hw/arm/virt: Use machine_memory_devices_init()")
Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 accel/kvm/kvm-all.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 373d876c05..c825cba12f 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2464,6 +2464,7 @@ static int kvm_init(MachineState *ms)
     qemu_mutex_init(&kml_slots_lock);
 
     s = KVM_STATE(ms->accelerator);
+    kvm_state = s;
 
     /*
      * On systems where the kernel can support different base page
@@ -2695,8 +2696,6 @@ static int kvm_init(MachineState *ms)
 #endif
     }
 
-    kvm_state = s;
-
     ret = kvm_arch_init(ms, s);
     if (ret < 0) {
         goto err;
-- 
2.41.0