ANDROID: KVM: arm64: Turn kvm_pgtable_stage2_set_owner into kvm_pgtable_stage2_annotate

kvm_pgtable_stage2_set_owner() could be generalised into a way
to store up to 63 bits in the page tables, as long as we don't
set bit 0.

Let's just do that.

Bug: 357781595
Change-Id: I4e42d149b457870c35a5ae0f77e14c95dee16b4d
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_pgtable.h

@@ -609,14 +609,16 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   void *mc, enum kvm_pgtable_walk_flags flags);
 
 /**
- * kvm_pgtable_stage2_set_owner() - Unmap and annotate pages in the IPA space to
- *				    track ownership.
+ * kvm_pgtable_stage2_annotate() - Unmap and annotate pages in the IPA space
+ *				   to track ownership (and more).
  * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init*().
  * @addr:	Base intermediate physical address to annotate.
  * @size:	Size of the annotated range.
  * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
  *		page-table pages.
- * @owner_id:	Unique identifier for the owner of the page.
+ * @annotation:	A 63 bit value that will be stored in the page tables.
+ *		@annotation[0] must be 0, and @annotation[63:1] is stored
+ *		in the page tables.
  *
  * By default, all page-tables are owned by identifier 0. This function can be
  * used to mark portions of the IPA space as owned by other entities. When a
@@ -625,8 +627,8 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
  *
  * Return: 0 on success, negative error code on failure.
  */
-int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
-				 void *mc, u8 owner_id);
+int kvm_pgtable_stage2_annotate(struct kvm_pgtable *pgt, u64 addr, u64 size,
+				void *mc, kvm_pte_t annotation);
 
 /**
  * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.

arch/arm64/kvm/hyp/nvhe/mem_protect.c

@@ -512,10 +512,25 @@ int host_stage2_idmap_locked(phys_addr_t addr, u64 size,
 	return host_stage2_try(__host_stage2_idmap, addr, addr + size, prot);
 }
 
+#define KVM_INVALID_PTE_OWNER_MASK	GENMASK(9, 2)
+#define KVM_MAX_OWNER_ID               FIELD_MAX(KVM_INVALID_PTE_OWNER_MASK)
+
+static kvm_pte_t kvm_init_invalid_leaf_owner(u8 owner_id)
+{
+	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
+}
+
 int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 {
-	return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
-			       addr, size, &host_s2_pool, owner_id);
+	kvm_pte_t annotation;
+
+	if (owner_id > KVM_MAX_OWNER_ID)
+		return -EINVAL;
+
+	annotation = kvm_init_invalid_leaf_owner(owner_id);
+
+	return host_stage2_try(kvm_pgtable_stage2_annotate, &host_mmu.pgt,
+			       addr, size, &host_s2_pool, annotation);
 }
 
 static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)

arch/arm64/kvm/hyp/pgtable.c

@@ -128,11 +128,6 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, s8 level)
 	return pte;
 }
 
-static kvm_pte_t kvm_init_invalid_leaf_owner(u8 owner_id)
-{
-	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
-}
-
 static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data,
 				  const struct kvm_pgtable_visit_ctx *ctx,
 				  enum kvm_pgtable_walk_flags visit)
@@ -577,7 +572,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
 struct stage2_map_data {
 	const u64			phys;
 	kvm_pte_t			attr;
-	u8				owner_id;
+	u64				annotation;
 
 	kvm_pte_t			*anchor;
 	kvm_pte_t			*childp;
@@ -926,7 +921,7 @@ static int stage2_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx,
 	if (kvm_phys_is_valid(phys))
 		new = kvm_init_valid_leaf_pte(phys, data->attr, ctx->level);
 	else
-		new = kvm_init_invalid_leaf_owner(data->owner_id);
+		new = data->annotation;
 
 	/*
 	 * Skip updating the PTE if we are trying to recreate the exact
@@ -1080,16 +1075,16 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	return ret;
 }
 
-int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
-				 void *mc, u8 owner_id)
+int kvm_pgtable_stage2_annotate(struct kvm_pgtable *pgt, u64 addr, u64 size,
+				void *mc, kvm_pte_t annotation)
 {
 	int ret;
 	struct stage2_map_data map_data = {
 		.phys		= KVM_PHYS_INVALID,
 		.mmu		= pgt->mmu,
 		.memcache	= mc,
-		.owner_id	= owner_id,
 		.force_pte	= true,
+		.annotation	= annotation,
 	};
 	struct kvm_pgtable_walker walker = {
 		.cb		= stage2_map_walker,
@@ -1098,7 +1093,7 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		.arg		= &map_data,
 	};
 
-	if (owner_id > KVM_MAX_OWNER_ID)
+	if (annotation & PTE_VALID)
 		return -EINVAL;
 
 	ret = kvm_pgtable_walk(pgt, addr, size, &walker);