KVM: x86: define SVM/VMX specific kvm_arch_[alloc|free]_vm

Define kvm_arch_[alloc|free]_vm in x86 as pass through functions
to new kvm_x86_ops vm_alloc and vm_free, and move the current
allocation logic as-is to SVM and VMX.  Vendor specific alloc/free
functions set the stage for SVM/VMX wrappers of 'struct kvm',
which will allow us to move the growing number of SVM/VMX specific
member variables out of 'struct kvm_arch'.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 9729b7e..12b8e38 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1717,6 +1717,16 @@ static void __unregister_enc_region_locked(struct kvm *kvm,
 	kfree(region);
 }
 
+static struct kvm *svm_vm_alloc(void)
+{
+	return kzalloc(sizeof(struct kvm), GFP_KERNEL);
+}
+
+static void svm_vm_free(struct kvm *kvm)
+{
+	kfree(kvm);
+}
+
 static void sev_vm_destroy(struct kvm *kvm)
 {
 	struct kvm_sev_info *sev = &kvm->arch.sev_info;
@@ -6881,6 +6891,8 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.vcpu_free = svm_free_vcpu,
 	.vcpu_reset = svm_vcpu_reset,
 
+	.vm_alloc = svm_vm_alloc,
+	.vm_free = svm_vm_free,
 	.vm_init = avic_vm_init,
 	.vm_destroy = svm_vm_destroy,