Apparently no TLB flush is needed when there's no valid rmap in memory slot.
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f83fc6c..d43bf50 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4309,6 +4309,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
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;
@@ -4325,7 +4326,8 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
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);
@@ -4352,7 +4354,8 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
* 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
--
2.1.0
--
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