On Thu, Mar 10, 2022, Chao Peng wrote:
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 67349421eae3..52319f49d58a 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -841,8 +841,43 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
> #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
>
> #ifdef CONFIG_MEMFILE_NOTIFIER
> +static void kvm_memfile_notifier_handler(struct memfile_notifier *notifier,
> + pgoff_t start, pgoff_t end)
> +{
> + int idx;
> + struct kvm_memory_slot *slot = container_of(notifier,
> + struct kvm_memory_slot,
> + notifier);
> + struct kvm_gfn_range gfn_range = {
> + .slot = slot,
> + .start = start - (slot->private_offset >> PAGE_SHIFT),
> + .end = end - (slot->private_offset >> PAGE_SHIFT),
> + .may_block = true,
> + };
> + struct kvm *kvm = slot->kvm;
> +
> + gfn_range.start = max(gfn_range.start, slot->base_gfn);
> + gfn_range.end = min(gfn_range.end, slot->base_gfn + slot->npages);
> +
> + if (gfn_range.start >= gfn_range.end)
> + return;
> +
> + idx = srcu_read_lock(&kvm->srcu);
> + KVM_MMU_LOCK(kvm);
> + kvm_unmap_gfn_range(kvm, &gfn_range);
> + kvm_flush_remote_tlbs(kvm);
This should check the result of kvm_unmap_gfn_range() and flush only if necessary.
kvm->mmu_notifier_seq needs to be incremented, otherwise KVM will incorrectly
install a SPTE if the mapping is zapped between retrieving the pfn in faultin and
installing it after acquire mmu_lock.
> + KVM_MMU_UNLOCK(kvm);
> + srcu_read_unlock(&kvm->srcu, idx);
> +}
> +
> +static struct memfile_notifier_ops kvm_memfile_notifier_ops = {
> + .invalidate = kvm_memfile_notifier_handler,
> + .fallocate = kvm_memfile_notifier_handler,
> +};
> +
> static inline int kvm_memfile_register(struct kvm_memory_slot *slot)
> {
> + slot->notifier.ops = &kvm_memfile_notifier_ops;
> return memfile_register_notifier(file_inode(slot->private_file),
> &slot->notifier,
> &slot->pfn_ops);
> @@ -1963,6 +1998,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> new->private_file = file;
> new->private_offset = mem->flags & KVM_MEM_PRIVATE ?
> region_ext->private_offset : 0;
> + new->kvm = kvm;
>
> r = kvm_set_memslot(kvm, old, new, change);
> if (!r)
> --
> 2.17.1
>
