Hi Alex,

On 11/17/21 7:38 AM, Alexandru Elisei wrote:
Unpin the backing pages mapped at stage 2 after the stage 2 translation
tables are destroyed.

Signed-off-by: Alexandru Elisei <alexandru.eli...@arm.com>
---
  arch/arm64/kvm/mmu.c | 23 ++++++++++++++++++-----
  1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index cd6f1bc7842d..072e2aba371f 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1627,11 +1627,19 @@ int kvm_mmu_lock_memslot(struct kvm *kvm, u64 slot, u64 
flags)
        return ret;
  }
-static void unlock_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot)
+static void __unlock_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot)
  {
        bool writable = memslot->arch.flags & KVM_MEMSLOT_LOCK_WRITE;
        unsigned long npages = memslot->npages;
+ unpin_memslot_pages(memslot, writable);
+       account_locked_vm(current->mm, npages, false);
+
+       memslot->arch.flags &= ~KVM_MEMSLOT_LOCK_MASK;
+}
+
+static void unlock_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
        /*
         * MMU maintenace operations aren't performed on an unlocked memslot.
         * Unmap it from stage 2 so the abort handler performs the necessary
@@ -1640,10 +1648,7 @@ static void unlock_memslot(struct kvm *kvm, struct 
kvm_memory_slot *memslot)
        if (kvm_mmu_has_pending_ops(kvm))
                kvm_arch_flush_shadow_memslot(kvm, memslot);
- unpin_memslot_pages(memslot, writable);
-       account_locked_vm(current->mm, npages, false);
-
-       memslot->arch.flags &= ~KVM_MEMSLOT_LOCK_MASK;
+       __unlock_memslot(kvm, memslot);
  }
int kvm_mmu_unlock_memslot(struct kvm *kvm, u64 slot, u64 flags)
@@ -1951,7 +1956,15 @@ void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
void kvm_arch_flush_shadow_all(struct kvm *kvm)
  {
+       struct kvm_memory_slot *memslot;
+
        kvm_free_stage2_pgd(&kvm->arch.mmu);
+
+       kvm_for_each_memslot(memslot, kvm_memslots(kvm)) {
+               if (!memslot_is_locked(memslot))
+                       continue;
+               __unlock_memslot(kvm, memslot);
+       }
  }

Perhaps it might be useful to manage the number of locked memslots ?
(can be used in the fix for kvm_mmu_unlock_memslot in the patch-7 as well)
Thanks,
Reiji


void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
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