KVM: arm64: Make memcache anonymous in pgtable allocator

The current stage2 page-table allocator uses a memcache to get
pre-allocated pages when it needs any. To allow re-using this code at
EL2 which uses a concept of memory pools, make the memcache argument of
kvm_pgtable_stage2_map() anonymous, and let the mm_ops zalloc_page()
callbacks use it the way they need to.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-26-qperret@google.com

arch/arm64/include/asm/kvm_pgtable.h

@@ -213,8 +213,8 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
  * @size:	Size of the mapping.
  * @phys:	Physical address of the memory to map.
  * @prot:	Permissions and attributes for the mapping.
- * @mc:		Cache of pre-allocated GFP_PGTABLE_USER memory from which to
- *		allocate page-table pages.
+ * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
+ *		page-table pages.
  *
  * The offset of @addr within a page is ignored, @size is rounded-up to
  * the next page boundary and @phys is rounded-down to the previous page
@@ -236,7 +236,7 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
  */
 int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   u64 phys, enum kvm_pgtable_prot prot,
-			   struct kvm_mmu_memory_cache *mc);
+			   void *mc);
 
 /**
  * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.

arch/arm64/kvm/hyp/pgtable.c

@@ -446,7 +446,7 @@ struct stage2_map_data {
 	kvm_pte_t			*anchor;
 
 	struct kvm_s2_mmu		*mmu;
-	struct kvm_mmu_memory_cache	*memcache;
+	void				*memcache;
 
 	struct kvm_pgtable_mm_ops	*mm_ops;
 };
@@ -670,7 +670,7 @@ static int stage2_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 
 int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   u64 phys, enum kvm_pgtable_prot prot,
-			   struct kvm_mmu_memory_cache *mc)
+			   void *mc)
 {
 	int ret;
 	struct stage2_map_data map_data = {