kvm: x86: Add a hook for arch specific dirty logging emulation

When KVM updates accessed/dirty bits, this hook can be used
to invoke an arch specific function that implements/emulates
dirty logging such as PML.

Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1020,6 +1020,8 @@ struct kvm_x86_ops {
 	void (*enable_log_dirty_pt_masked)(struct kvm *kvm,
 					   struct kvm_memory_slot *slot,
 					   gfn_t offset, unsigned long mask);
+	int (*write_log_dirty)(struct kvm_vcpu *vcpu);
+
 	/* pmu operations of sub-arch */
 	const struct kvm_pmu_ops *pmu_ops;