KVM: x86: Introducing kvm_x86_ops VM init/destroy hooks

Adding function pointers in struct kvm_x86_ops for processor-specific
layer to provide hooks for when KVM initialize and destroy VM.
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

CVE-2018-3620
CVE-2018-3646

(backported from commit 03543133 upstream)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

arch/x86/include/asm/kvm_host.h

@@ -801,6 +801,9 @@ struct kvm_x86_ops {
 	bool (*has_emulated_msr)(int index);
 	void (*cpuid_update)(struct kvm_vcpu *vcpu);
 
+	int (*vm_init)(struct kvm *kvm);
+	void (*vm_destroy)(struct kvm *kvm);
+
 	/* Create, but do not attach this VCPU */
 	struct kvm_vcpu *(*vcpu_create)(struct kvm *kvm, unsigned id);
 	void (*vcpu_free)(struct kvm_vcpu *vcpu);

arch/x86/kvm/x86.c

@@ -7784,6 +7784,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn);
 	INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);
 
+	if (kvm_x86_ops->vm_init)
+		return kvm_x86_ops->vm_init(kvm);
+
 	return 0;
 }
 
@@ -7905,6 +7908,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 		x86_set_memory_region(kvm, IDENTITY_PAGETABLE_PRIVATE_MEMSLOT, 0, 0);
 		x86_set_memory_region(kvm, TSS_PRIVATE_MEMSLOT, 0, 0);
 	}
+	if (kvm_x86_ops->vm_destroy)
+		kvm_x86_ops->vm_destroy(kvm);
 	kvm_iommu_unmap_guest(kvm);
 	kfree(kvm->arch.vpic);
 	kfree(kvm->arch.vioapic);