Optimize TLB flush in kvm_mmu_slot_remove_write_access.
No TLB flush is needed when there's no valid rmap in memory slot.
Signed-off-by: Kai Huang <kai.huang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 0d0fdd6..97898ab 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4302,6 +4302,7 @@
struct kvm_memory_slot *memslot;
gfn_t last_gfn;
int i;
+ bool flush = false;
memslot = id_to_memslot(kvm->memslots, slot);
last_gfn = memslot->base_gfn + memslot->npages - 1;
@@ -4318,7 +4319,8 @@
for (index = 0; index <= last_index; ++index, ++rmapp) {
if (*rmapp)
- __rmap_write_protect(kvm, rmapp, false);
+ flush |= __rmap_write_protect(kvm, rmapp,
+ false);
if (need_resched() || spin_needbreak(&kvm->mmu_lock))
cond_resched_lock(&kvm->mmu_lock);
@@ -4345,7 +4347,8 @@
* instead of PT_WRITABLE_MASK, that means it does not depend
* on PT_WRITABLE_MASK anymore.
*/
- kvm_flush_remote_tlbs(kvm);
+ if (flush)
+ kvm_flush_remote_tlbs(kvm);
}
#define BATCH_ZAP_PAGES 10