KVM: MMU: delay flush all tlbs on sync_page path
Quote from Avi:
| I don't think we need to flush immediately; set a "tlb dirty" bit somewhere
| that is cleareded when we flush the tlb. kvm_mmu_notifier_invalidate_page()
| can consult the bit and force a flush if set.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5156d45..ee99b77 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -168,8 +168,12 @@
void kvm_flush_remote_tlbs(struct kvm *kvm)
{
+ int dirty_count = kvm->tlbs_dirty;
+
+ smp_mb();
if (make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
++kvm->stat.remote_tlb_flush;
+ cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);
}
void kvm_reload_remote_mmus(struct kvm *kvm)
@@ -249,7 +253,7 @@
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
kvm->mmu_notifier_seq++;
- need_tlb_flush = kvm_unmap_hva(kvm, address);
+ need_tlb_flush = kvm_unmap_hva(kvm, address) | kvm->tlbs_dirty;
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
@@ -293,6 +297,7 @@
kvm->mmu_notifier_count++;
for (; start < end; start += PAGE_SIZE)
need_tlb_flush |= kvm_unmap_hva(kvm, start);
+ need_tlb_flush |= kvm->tlbs_dirty;
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);