KVM: x86/mmu: Merge flush and non-flush tdp_mmu_iter_cond_resched

The flushing and non-flushing variants of tdp_mmu_iter_cond_resched have
almost identical implementations. Merge the two functions and add a
flush parameter.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-12-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/tdp_mmu.c

@@ -443,33 +443,13 @@ static inline void tdp_mmu_set_spte_no_dirty_log(struct kvm *kvm,
 	for_each_tdp_pte(_iter, __va(_mmu->root_hpa),		\
 			 _mmu->shadow_root_level, _start, _end)
 
-/*
- * Flush the TLB and yield if the MMU lock is contended or this thread needs to
- * return control to the scheduler.
- *
- * If this function yields, it will also reset the tdp_iter's walk over the
- * paging structure and the calling function should allow the iterator to
- * continue its traversal from the paging structure root.
- *
- * Return true if this function yielded, the TLBs were flushed, and the
- * iterator's traversal was reset. Return false if a yield was not needed.
- */
-static bool tdp_mmu_iter_flush_cond_resched(struct kvm *kvm, struct tdp_iter *iter)
-{
-	if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
-		kvm_flush_remote_tlbs(kvm);
-		cond_resched_lock(&kvm->mmu_lock);
-		tdp_iter_refresh_walk(iter);
-		return true;
-	}
-
-	return false;
-}
-
 /*
  * Yield if the MMU lock is contended or this thread needs to return control
  * to the scheduler.
  *
+ * If this function should yield and flush is set, it will perform a remote
+ * TLB flush before yielding.
+ *
  * If this function yields, it will also reset the tdp_iter's walk over the
  * paging structure and the calling function should allow the iterator to
  * continue its traversal from the paging structure root.
@@ -477,9 +457,13 @@ static bool tdp_mmu_iter_flush_cond_resched(struct kvm *kvm, struct tdp_iter *it
  * Return true if this function yielded and the iterator's traversal was reset.
  * Return false if a yield was not needed.
  */
-static bool tdp_mmu_iter_cond_resched(struct kvm *kvm, struct tdp_iter *iter)
+static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm,
+					     struct tdp_iter *iter, bool flush)
 {
 	if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
+		if (flush)
+			kvm_flush_remote_tlbs(kvm);
+
 		cond_resched_lock(&kvm->mmu_lock);
 		tdp_iter_refresh_walk(iter);
 		return true;
@@ -522,7 +506,7 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
 		tdp_mmu_set_spte(kvm, &iter, 0);
 
 		flush_needed = !can_yield ||
-			       !tdp_mmu_iter_flush_cond_resched(kvm, &iter);
+			       !tdp_mmu_iter_cond_resched(kvm, &iter, true);
 	}
 	return flush_needed;
 }
@@ -894,7 +878,7 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
 		tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte);
 		spte_set = true;
 
-		tdp_mmu_iter_cond_resched(kvm, &iter);
+		tdp_mmu_iter_cond_resched(kvm, &iter, false);
 	}
 	return spte_set;
 }
@@ -953,7 +937,7 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
 		tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte);
 		spte_set = true;
 
-		tdp_mmu_iter_cond_resched(kvm, &iter);
+		tdp_mmu_iter_cond_resched(kvm, &iter, false);
 	}
 	return spte_set;
 }
@@ -1069,7 +1053,7 @@ static bool set_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
 		tdp_mmu_set_spte(kvm, &iter, new_spte);
 		spte_set = true;
 
-		tdp_mmu_iter_cond_resched(kvm, &iter);
+		tdp_mmu_iter_cond_resched(kvm, &iter, false);
 	}
 
 	return spte_set;
@@ -1121,7 +1105,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
 
 		tdp_mmu_set_spte(kvm, &iter, 0);
 
-		spte_set = !tdp_mmu_iter_flush_cond_resched(kvm, &iter);
+		spte_set = !tdp_mmu_iter_cond_resched(kvm, &iter, true);
 	}
 
 	if (spte_set)