KVM: const-ify all relevant uses of struct kvm_memory_slot

As alluded to in commit f36f3f2846 ("KVM: add "new" argument to
kvm_arch_commit_memory_region"), a bunch of other places where struct
kvm_memory_slot is used, needs to be refactored to preserve the
"const"ness of struct kvm_memory_slot across-the-board.

Signed-off-by: Hamza Mahfooz <someguy@effective-light.com>
Message-Id: <20210713023338.57108-1-someguy@effective-light.com>
[Do not touch body of slot_rmap_walk_init. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1537,12 +1537,12 @@ void kvm_mmu_uninit_vm(struct kvm *kvm);
 void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu);
 void kvm_mmu_reset_context(struct kvm_vcpu *vcpu);
 void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
-				      struct kvm_memory_slot *memslot,
+				      const struct kvm_memory_slot *memslot,
 				      int start_level);
 void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
 				   const struct kvm_memory_slot *memslot);
 void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
-				   struct kvm_memory_slot *memslot);
+				   const struct kvm_memory_slot *memslot);
 void kvm_mmu_zap_all(struct kvm *kvm);
 void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen);
 unsigned long kvm_mmu_calculate_default_mmu_pages(struct kvm *kvm);

arch/x86/kvm/mmu/mmu.c

@@ -794,7 +794,7 @@ static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn,
 	return &slot->arch.lpage_info[level - 2][idx];
 }
 
-static void update_gfn_disallow_lpage_count(struct kvm_memory_slot *slot,
+static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot,
 					    gfn_t gfn, int count)
 {
 	struct kvm_lpage_info *linfo;
@@ -807,12 +807,12 @@ static void update_gfn_disallow_lpage_count(struct kvm_memory_slot *slot,
 	}
 }
 
-void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
+void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn)
 {
 	update_gfn_disallow_lpage_count(slot, gfn, 1);
 }
 
-void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn)
+void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn)
 {
 	update_gfn_disallow_lpage_count(slot, gfn, -1);
 }
@@ -999,7 +999,7 @@ static void pte_list_remove(struct kvm_rmap_head *rmap_head, u64 *sptep)
 }
 
 static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level,
-					   struct kvm_memory_slot *slot)
+					   const struct kvm_memory_slot *slot)
 {
 	unsigned long idx;
 
@@ -1228,7 +1228,7 @@ static bool spte_wrprot_for_clear_dirty(u64 *sptep)
  * Returns true iff any D or W bits were cleared.
  */
 static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-			       struct kvm_memory_slot *slot)
+			       const struct kvm_memory_slot *slot)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
@@ -1387,7 +1387,7 @@ static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
 }
 
 static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-			  struct kvm_memory_slot *slot)
+			  const struct kvm_memory_slot *slot)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
@@ -1452,7 +1452,7 @@ restart:
 
 struct slot_rmap_walk_iterator {
 	/* input fields. */
-	struct kvm_memory_slot *slot;
+	const struct kvm_memory_slot *slot;
 	gfn_t start_gfn;
 	gfn_t end_gfn;
 	int start_level;
@@ -1479,7 +1479,7 @@ rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level)
 
 static void
 slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator,
-		    struct kvm_memory_slot *slot, int start_level,
+		    const struct kvm_memory_slot *slot, int start_level,
 		    int end_level, gfn_t start_gfn, gfn_t end_gfn)
 {
 	iterator->slot = slot;
@@ -5313,12 +5313,13 @@ void kvm_configure_mmu(bool enable_tdp, int tdp_max_root_level,
 EXPORT_SYMBOL_GPL(kvm_configure_mmu);
 
 /* The return value indicates if tlb flush on all vcpus is needed. */
-typedef bool (*slot_level_handler) (struct kvm *kvm, struct kvm_rmap_head *rmap_head,
-				    struct kvm_memory_slot *slot);
+typedef bool (*slot_level_handler) (struct kvm *kvm,
+				    struct kvm_rmap_head *rmap_head,
+				    const struct kvm_memory_slot *slot);
 
 /* The caller should hold mmu-lock before calling this function. */
 static __always_inline bool
-slot_handle_level_range(struct kvm *kvm, struct kvm_memory_slot *memslot,
+slot_handle_level_range(struct kvm *kvm, const struct kvm_memory_slot *memslot,
 			slot_level_handler fn, int start_level, int end_level,
 			gfn_t start_gfn, gfn_t end_gfn, bool flush_on_yield,
 			bool flush)
@@ -5345,7 +5346,7 @@ slot_handle_level_range(struct kvm *kvm, struct kvm_memory_slot *memslot,
 }
 
 static __always_inline bool
-slot_handle_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
+slot_handle_level(struct kvm *kvm, const struct kvm_memory_slot *memslot,
 		  slot_level_handler fn, int start_level, int end_level,
 		  bool flush_on_yield)
 {
@@ -5356,7 +5357,7 @@ slot_handle_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
 }
 
 static __always_inline bool
-slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot,
+slot_handle_leaf(struct kvm *kvm, const struct kvm_memory_slot *memslot,
 		 slot_level_handler fn, bool flush_on_yield)
 {
 	return slot_handle_level(kvm, memslot, fn, PG_LEVEL_4K,
@@ -5615,7 +5616,8 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 				if (start >= end)
 					continue;
 
-				flush = slot_handle_level_range(kvm, memslot,
+				flush = slot_handle_level_range(kvm,
+						(const struct kvm_memory_slot *) memslot,
 						kvm_zap_rmapp, PG_LEVEL_4K,
 						KVM_MAX_HUGEPAGE_LEVEL, start,
 						end - 1, true, flush);
@@ -5643,13 +5645,13 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 
 static bool slot_rmap_write_protect(struct kvm *kvm,
 				    struct kvm_rmap_head *rmap_head,
-				    struct kvm_memory_slot *slot)
+				    const struct kvm_memory_slot *slot)
 {
 	return __rmap_write_protect(kvm, rmap_head, false);
 }
 
 void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
-				      struct kvm_memory_slot *memslot,
+				      const struct kvm_memory_slot *memslot,
 				      int start_level)
 {
 	bool flush = false;
@@ -5685,7 +5687,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
 
 static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 					 struct kvm_rmap_head *rmap_head,
-					 struct kvm_memory_slot *slot)
+					 const struct kvm_memory_slot *slot)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
@@ -5724,10 +5726,8 @@ restart:
 }
 
 void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
-				   const struct kvm_memory_slot *memslot)
+				   const struct kvm_memory_slot *slot)
 {
-	/* FIXME: const-ify all uses of struct kvm_memory_slot.  */
-	struct kvm_memory_slot *slot = (struct kvm_memory_slot *)memslot;
 	bool flush = false;
 
 	if (kvm_memslots_have_rmaps(kvm)) {
@@ -5763,7 +5763,7 @@ void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
 }
 
 void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
-				   struct kvm_memory_slot *memslot)
+				   const struct kvm_memory_slot *memslot)
 {
 	bool flush = false;
 

arch/x86/kvm/mmu/mmu_internal.h

@@ -124,8 +124,8 @@ static inline bool is_nx_huge_page_enabled(void)
 
 int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync);
 
-void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
-void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
+void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
+void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
 				    struct kvm_memory_slot *slot, u64 gfn,
 				    int min_level);

arch/x86/kvm/mmu/tdp_mmu.c

@@ -1246,8 +1246,8 @@ retry:
  * only affect leaf SPTEs down to min_level.
  * Returns true if an SPTE has been changed and the TLBs need to be flushed.
  */
-bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			     int min_level)
+bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm,
+			     const struct kvm_memory_slot *slot, int min_level)
 {
 	struct kvm_mmu_page *root;
 	bool spte_set = false;
@@ -1317,7 +1317,8 @@ retry:
  * each SPTE. Returns true if an SPTE has been changed and the TLBs need to
  * be flushed.
  */
-bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, struct kvm_memory_slot *slot)
+bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm,
+				  const struct kvm_memory_slot *slot)
 {
 	struct kvm_mmu_page *root;
 	bool spte_set = false;

arch/x86/kvm/mmu/tdp_mmu.h

@@ -61,10 +61,10 @@ bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range);
 bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
 bool kvm_tdp_mmu_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range);
 
-bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			     int min_level);
+bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm,
+			     const struct kvm_memory_slot *slot, int min_level);
 bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm,
-				  struct kvm_memory_slot *slot);
+				  const struct kvm_memory_slot *slot);
 void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm,
 				       struct kvm_memory_slot *slot,
 				       gfn_t gfn, unsigned long mask,

arch/x86/kvm/x86.c

@@ -11520,7 +11520,7 @@ static void kvm_mmu_update_cpu_dirty_logging(struct kvm *kvm, bool enable)
 
 static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
 				     struct kvm_memory_slot *old,
-				     struct kvm_memory_slot *new,
+				     const struct kvm_memory_slot *new,
 				     enum kvm_mr_change change)
 {
 	bool log_dirty_pages = new->flags & KVM_MEM_LOG_DIRTY_PAGES;
@@ -11600,10 +11600,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 		kvm_mmu_change_mmu_pages(kvm,
 				kvm_mmu_calculate_default_mmu_pages(kvm));
 
-	/*
-	 * FIXME: const-ify all uses of struct kvm_memory_slot.
-	 */
-	kvm_mmu_slot_apply_flags(kvm, old, (struct kvm_memory_slot *) new, change);
+	kvm_mmu_slot_apply_flags(kvm, old, new, change);
 
 	/* Free the arrays associated with the old memslot. */
 	if (change == KVM_MR_MOVE)