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* [PATCH v3] KVM: const-ify all relevant uses of struct kvm_memory_slot
@ 2021-08-02 19:43 Hamza Mahfooz
  0 siblings, 0 replies; only message in thread
From: Hamza Mahfooz @ 2021-08-02 19:43 UTC (permalink / raw)
  To: linux-kernel
  Cc: Peter Xu, Hamza Mahfooz, Paolo Bonzini, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86,
	H. Peter Anvin, kvm

As alluded to in commit f36f3f2846b5 ("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>
---
v2: fix an issue regarding an incorrect start_level being passed to
    rmap_walk_init_level()

v3: apparently the memcpy() is redundant, so revert the body of
    slot_rmap_walk_init() back to it's previous state.
---
 arch/x86/include/asm/kvm_host.h |  4 ++--
 arch/x86/kvm/mmu/mmu.c          | 42 ++++++++++++++++-----------------
 arch/x86/kvm/mmu/mmu_internal.h |  4 ++--
 arch/x86/kvm/mmu/tdp_mmu.c      |  7 +++---
 arch/x86/kvm/mmu/tdp_mmu.h      |  6 ++---
 arch/x86/kvm/x86.c              |  7 ++----
 6 files changed, 34 insertions(+), 36 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 974cbfb1eefe..a195e1c32018 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1536,12 +1536,12 @@ 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);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 66f7f5bc3482..833b493d87bf 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -786,7 +786,7 @@ 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;
@@ -799,12 +799,12 @@ 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);
 }
@@ -991,7 +991,7 @@ 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;
 
@@ -1218,7 +1218,7 @@ 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;
@@ -1377,7 +1377,7 @@ 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;
@@ -1442,7 +1442,7 @@ static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 
 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;
@@ -1469,7 +1469,7 @@ 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;
@@ -5276,12 +5276,13 @@ 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)
@@ -5308,7 +5309,7 @@ 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)
 {
@@ -5319,7 +5320,7 @@ 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,
@@ -5578,7 +5579,8 @@ 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);
@@ -5606,13 +5608,13 @@ 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;
@@ -5648,7 +5650,7 @@ 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;
@@ -5687,10 +5689,8 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 }
 
 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)) {
@@ -5726,7 +5726,7 @@ 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;
 
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 35567293c1fd..ee4ad9c99219 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/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);
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 0853370bd811..5d8d69d56a81 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1242,8 +1242,8 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
  * 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;
@@ -1313,7 +1313,8 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
  * 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;
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index 1cae4485b3bc..49437dbb4804 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/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,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4116567f3d44..9f59f67e724b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11472,7 +11472,7 @@ 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;
@@ -11552,10 +11552,7 @@ 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)
-- 
2.32.0


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