KVM: selftests: Add arch specific post vm creation hook

Add arch specific API kvm_arch_vm_post_create to perform any required setup
after VM creation.
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Reviewed-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>
Link: https://lore.kernel.org/r/20221115213845.3348210-4-vannapurve@google.com
[sean: place x86's implementation by vm_arch_vcpu_add()]
Signed-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/include/kvm_util_base.h

@@ -864,4 +864,6 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
  */
 void kvm_selftest_arch_init(void);
 
+void kvm_arch_vm_post_create(struct kvm_vm *vm);
+
 #endif /* SELFTEST_KVM_UTIL_BASE_H */

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -351,9 +351,7 @@ struct kvm_vm *__vm_create(enum vm_guest_mode mode, uint32_t nr_runnable_vcpus,
 	slot0 = memslot2region(vm, 0);
 	ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size);
 
-#ifdef __x86_64__
-	vm_create_irqchip(vm);
-#endif
+	kvm_arch_vm_post_create(vm);
 
 	return vm;
 }
@@ -2087,6 +2085,10 @@ void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data,
 	}
 }
 
+__weak void kvm_arch_vm_post_create(struct kvm_vm *vm)
+{
+}
+
 __weak void kvm_selftest_arch_init(void)
 {
 }

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -586,6 +586,11 @@ void __vm_xsave_require_permission(int bit, const char *name)
 		    bitmask);
 }
 
+void kvm_arch_vm_post_create(struct kvm_vm *vm)
+{
+	vm_create_irqchip(vm);
+}
+
 struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
 				  void *guest_code)
 {