1 files changed, 46 insertions, 12 deletions

diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
index 34233d586060..dee1a406b0c2 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -8,23 +8,30 @@
 #include <linux/types.h>
 
 /*
- * Bits 0-1 are reserved to track the memory ownership state of each page:
- *   00: The page is owned exclusively by the page-table owner.
- *   01: The page is owned by the page-table owner, but is shared
- *       with another entity.
- *   10: The page is shared with, but not owned by the page-table owner.
- *   11: Reserved for future use (lending).
+ * Bits 0-1 are used to encode the memory ownership state of each page from the
+ * point of view of a pKVM "component" (host, hyp, guest, ... see enum
+ * pkvm_component_id):
+ *   00: The page is owned and exclusively accessible by the component;
+ *   01: The page is owned and accessible by the component, but is also
+ *       accessible by another component;
+ *   10: The page is accessible but not owned by the component;
+ * The storage of this state depends on the component: either in the
+ * hyp_vmemmap for the host and hyp states or in PTE software bits for guests.
  */
 enum pkvm_page_state {
 	PKVM_PAGE_OWNED			= 0ULL,
 	PKVM_PAGE_SHARED_OWNED		= BIT(0),
 	PKVM_PAGE_SHARED_BORROWED	= BIT(1),
-	__PKVM_PAGE_RESERVED		= BIT(0) | BIT(1),
 
-	/* Meta-states which aren't encoded directly in the PTE's SW bits */
-	PKVM_NOPAGE			= BIT(2),
+	/*
+	 * 'Meta-states' are not stored directly in PTE SW bits for guest
+	 * states, but inferred from the context (e.g. invalid PTE entries).
+	 * For the host and hyp, meta-states are stored directly in the
+	 * struct hyp_page.
+	 */
+	PKVM_NOPAGE			= BIT(0) | BIT(1),
 };
-#define PKVM_PAGE_META_STATES_MASK	(~__PKVM_PAGE_RESERVED)
+#define PKVM_PAGE_STATE_MASK		(BIT(0) | BIT(1))
 
 #define PKVM_PAGE_STATE_PROT_MASK	(KVM_PGTABLE_PROT_SW0 | KVM_PGTABLE_PROT_SW1)
 static inline enum kvm_pgtable_prot pkvm_mkstate(enum kvm_pgtable_prot prot,
@@ -44,8 +51,15 @@ struct hyp_page {
 	u16 refcount;
 	u8 order;
 
-	/* Host (non-meta) state. Guarded by the host stage-2 lock. */
-	enum pkvm_page_state host_state : 8;
+	/* Host state. Guarded by the host stage-2 lock. */
+	unsigned __host_state : 4;
+
+	/*
+	 * Complement of the hyp state. Guarded by the hyp stage-1 lock. We use
+	 * the complement so that the initial 0 in __hyp_state_comp (due to the
+	 * entire vmemmap starting off zeroed) encodes PKVM_NOPAGE.
+	 */
+	unsigned __hyp_state_comp : 4;
 
 	u32 host_share_guest_count;
 };
@@ -82,6 +96,26 @@ static inline struct hyp_page *hyp_phys_to_page(phys_addr_t phys)
 #define hyp_page_to_virt(page)	__hyp_va(hyp_page_to_phys(page))
 #define hyp_page_to_pool(page)	(((struct hyp_page *)page)->pool)
 
+static inline enum pkvm_page_state get_host_state(struct hyp_page *p)
+{
+	return p->__host_state;
+}
+
+static inline void set_host_state(struct hyp_page *p, enum pkvm_page_state state)
+{
+	p->__host_state = state;
+}
+
+static inline enum pkvm_page_state get_hyp_state(struct hyp_page *p)
+{
+	return p->__hyp_state_comp ^ PKVM_PAGE_STATE_MASK;
+}
+
+static inline void set_hyp_state(struct hyp_page *p, enum pkvm_page_state state)
+{
+	p->__hyp_state_comp = state ^ PKVM_PAGE_STATE_MASK;
+}
+
 /*
  * Refcounting for 'struct hyp_page'.
  * hyp_pool::lock must be held if atomic access to the refcount is required.