KVM: PPC: book3s: fix build error caused by gfn_to_hva_memslot()

The build error was caused by that builtin functions are calling
the functions implemented in modules. This error was introduced by
commit 4d8b81ab ("KVM: introduce readonly memslot").

The patch fixes the build error by moving function __gfn_to_hva_memslot()
from kvm_main.c to kvm_host.h and making that "inline" so that the
builtin function (kvmppc_h_enter) can use that.
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/powerpc/kvm/book3s_hv_rm_mmu.c

@@ -197,7 +197,7 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 		pa &= PAGE_MASK;
 	} else {
 		/* Translate to host virtual address */
-		hva = gfn_to_hva_memslot(memslot, gfn);
+		hva = __gfn_to_hva_memslot(memslot, gfn);
 
 		/* Look up the Linux PTE for the backing page */
 		pte_size = psize;

include/linux/kvm_host.h

@@ -773,6 +773,12 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
 	return search_memslots(slots, gfn);
 }
 
+static inline unsigned long
+__gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	return slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE;
+}
+
 static inline int memslot_id(struct kvm *kvm, gfn_t gfn)
 {
 	return gfn_to_memslot(kvm, gfn)->id;

virt/kvm/kvm_main.c

@@ -984,12 +984,6 @@ static bool memslot_is_readonly(struct kvm_memory_slot *slot)
 	return slot->flags & KVM_MEM_READONLY;
 }
 
-static unsigned long __gfn_to_hva_memslot(struct kvm_memory_slot *slot,
-					  gfn_t gfn)
-{
-	return slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE;
-}
-
 static unsigned long __gfn_to_hva_many(struct kvm_memory_slot *slot, gfn_t gfn,
 				       gfn_t *nr_pages, bool write)
 {