KVM: Move gfn_to_memslot() to kvm_host.h

This moves __gfn_to_memslot() and search_memslots() from kvm_main.c to
kvm_host.h to reduce the code duplication caused by the need for
non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c to call
gfn_to_memslot() in real mode.

Rather than putting gfn_to_memslot() itself in a header, which would
lead to increased code size, this puts __gfn_to_memslot() in a header.
Then, the non-modular uses of gfn_to_memslot() are changed to call
__gfn_to_memslot() instead.  This way there is only one place in the
source code that needs to be changed should the gfn_to_memslot()
implementation need to be modified.

On powerpc, the Book3S HV style of KVM has code that is called from
real mode which needs to call gfn_to_memslot() and thus needs this.
(Module code is allocated in the vmalloc region, which can't be
accessed in real mode.)

With this, we can remove builtin_gfn_to_memslot() from book3s_hv_rm_mmu.c.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9f32bff..470e305 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -640,19 +640,6 @@
 }
 #endif /* !CONFIG_S390 */
 
-static struct kvm_memory_slot *
-search_memslots(struct kvm_memslots *slots, gfn_t gfn)
-{
-	struct kvm_memory_slot *memslot;
-
-	kvm_for_each_memslot(memslot, slots)
-		if (gfn >= memslot->base_gfn &&
-		      gfn < memslot->base_gfn + memslot->npages)
-			return memslot;
-
-	return NULL;
-}
-
 static int cmp_memslot(const void *slot1, const void *slot2)
 {
 	struct kvm_memory_slot *s1, *s2;
@@ -1031,12 +1018,6 @@
 }
 EXPORT_SYMBOL_GPL(kvm_is_error_hva);
 
-static struct kvm_memory_slot *__gfn_to_memslot(struct kvm_memslots *slots,
-						gfn_t gfn)
-{
-	return search_memslots(slots, gfn);
-}
-
 struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 {
 	return __gfn_to_memslot(kvm_memslots(kvm), gfn);
@@ -1459,7 +1440,7 @@
 
 	ghc->gpa = gpa;
 	ghc->generation = slots->generation;
-	ghc->memslot = __gfn_to_memslot(slots, gfn);
+	ghc->memslot = gfn_to_memslot(kvm, gfn);
 	ghc->hva = gfn_to_hva_many(ghc->memslot, gfn, NULL);
 	if (!kvm_is_error_hva(ghc->hva))
 		ghc->hva += offset;