[v2,21/27] Revert "KVM: x86: use the fast way to invalidate all pages"

Commit Message

Sean Christopherson Feb. 5, 2019, 9:01 p.m. UTC

Revert to a slow kvm_mmu_zap_all() for kvm_arch_flush_shadow_all().
Flushing all shadow entries is only done during VM teardown, i.e.
kvm_arch_flush_shadow_all() is only called when the associated MM struct
is being released or when the VM instance is being freed.

Although the performance of teardown itself isn't critical, KVM should
still voluntarily schedule to play nice with the rest of the kernel;
but that can be done without the fast invalidate mechanism in a future
patch.

This reverts commit 6ca18b6950f8dee29361722f28f69847724b276f.

Cc: Xiao Guangrong <[e-mail]>
Signed-off-by: Sean Christopherson <[e-mail]>
---
 arch/x86/kvm/mmu.c | 15 +++++++++++++++
 arch/x86/kvm/x86.c |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

Patch

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 6beaa4575724..bdba6c85f81f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -5843,6 +5843,21 @@  void kvm_mmu_slot_set_dirty(struct kvm *kvm,
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_slot_set_dirty);
 
+void kvm_mmu_zap_all(struct kvm *kvm)
+{
+	struct kvm_mmu_page *sp, *node;
+	LIST_HEAD(invalid_list);
+
+	spin_lock(&kvm->mmu_lock);
+restart:
+	list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link)
+		if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list))
+			goto restart;
+
+	kvm_mmu_commit_zap_page(kvm, &invalid_list);
+	spin_unlock(&kvm->mmu_lock);
+}
+
 static void kvm_zap_obsolete_pages(struct kvm *kvm)
 {
 	struct kvm_mmu_page *sp, *node;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 365dfda14cd6..a6b9c4f5ccc7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9450,7 +9450,7 @@  void kvm_arch_commit_memory_region(struct kvm *kvm,
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
 {
-	kvm_mmu_invalidate_zap_all_pages(kvm);
+	kvm_mmu_zap_all(kvm);
 }
 
 void kvm_arch_flush_shadow_memslot(struct kvm *kvm,