[PATCH 8/11] KVM: Make kvm_arch_mmu_enable_log_dirty_pt_masked() return value

[lantianyu1986 at gmail.com]

From: Lan Tianyu <Tianyu.Lan at microsoft.com>

This patch is to make kvm_arch_mmu_enable_log_dirty_pt_masked() return value
and caller can use it to determine whether tlb flush is necessary.
kvm_get_dirty_log_protect() and kvm_clear_dirty_log_protect() use the return
value of kvm_arch_mmu_enable_log_dirty_pt_masked() to populate flush
parameter.

Signed-off-by: Lan Tianyu <Tianyu.Lan at microsoft.com>
---
 arch/mips/kvm/mmu.c      |  5 ++++-
 arch/x86/kvm/mmu.c       |  6 +++++-
 include/linux/kvm_host.h |  2 +-
 virt/kvm/arm/mmu.c       |  5 ++++-
 virt/kvm/kvm_main.c      | 10 ++++------
 5 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index 97e538a8c1be..f36ccb2d43ec 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -437,8 +437,10 @@ int kvm_mips_mkclean_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn)
  *
  * Walks bits set in mask write protects the associated pte's. Caller must
  * acquire @kvm->mmu_lock.
+ *
+ * Returns: Whether caller needs to flush tlb.
  */
-void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
+bool kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 		struct kvm_memory_slot *slot,
 		gfn_t gfn_offset, unsigned long mask)
 {
@@ -447,6 +449,7 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 	gfn_t end = base_gfn + __fls(mask);
 
 	kvm_mips_mkclean_gpa_pt(kvm, start, end);
+	return true;
 }
 
 /*
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 6d4f7dfeaa57..9d8ee6ea02db 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1676,8 +1676,10 @@ EXPORT_SYMBOL_GPL(kvm_mmu_clear_dirty_pt_masked);
  *
  * Used when we do not need to care about huge page mappings: e.g. during dirty
  * logging we do not have any such mappings.
+ *
+ * Return value means whether caller needs to flush tlb.
  */
-void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
+bool kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 				struct kvm_memory_slot *slot,
 				gfn_t gfn_offset, unsigned long mask)
 {
@@ -1686,6 +1688,8 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 				mask);
 	else
 		kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
+
+	return true;
 }
 
 /**
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c38cc5eb7e73..e86b8c38342b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -759,7 +759,7 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
 int kvm_clear_dirty_log_protect(struct kvm *kvm,
 				struct kvm_clear_dirty_log *log, bool *flush);
 
-void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
+bool kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 					struct kvm_memory_slot *slot,
 					gfn_t gfn_offset,
 					unsigned long mask);
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 3053bf2584f8..232007ff3208 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1564,12 +1564,15 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
  *
  * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to
  * enable dirty logging for them.
+ *
+ * Return value means whether caller needs to flush tlb.
  */
-void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
+bool kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 		struct kvm_memory_slot *slot,
 		gfn_t gfn_offset, unsigned long mask)
 {
 	kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
+	return true;
 }
 
 static void clean_dcache_guest_page(kvm_pfn_t pfn, unsigned long size)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e75dbb15fd09..bcbe059d98be 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1202,13 +1202,12 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
 			if (!dirty_bitmap[i])
 				continue;
 
-			*flush = true;
 			mask = xchg(&dirty_bitmap[i], 0);
 			dirty_bitmap_buffer[i] = mask;
 
 			offset = i * BITS_PER_LONG;
-			kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
-								offset, mask);
+			*flush = kvm_arch_mmu_enable_log_dirty_pt_masked(kvm,
+							memslot, offset, mask);
 		}
 		spin_unlock(&kvm->mmu_lock);
 	}
@@ -1275,9 +1274,8 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
 		 * a problem if userspace sets them in log->dirty_bitmap.
 		*/
 		if (mask) {
-			*flush = true;
-			kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
-								offset, mask);
+			*flush = kvm_arch_mmu_enable_log_dirty_pt_masked(kvm,
+					memslot, offset, mask);
 		}
 	}
 	spin_unlock(&kvm->mmu_lock);
-- 
2.14.4