KVM: PPC: Book3S HV: Reset reverse-map chains when resetting the HPT
With HV-style KVM, we maintain reverse-mapping lists that enable us to find all the HPT (hashed page table) entries that reference each guest physical page, with the heads of the lists in the memslot->arch.rmap arrays. When we reset the HPT (i.e. when we reboot the VM), we clear out all the HPT entries but we were not clearing out the reverse mapping lists. The result is that as we create new HPT entries, the lists get corrupted, which can easily lead to loops, resulting in the host kernel hanging when it tries to traverse those lists. This fixes the problem by zeroing out all the reverse mapping lists when we zero out the HPT. This incidentally means that we are also zeroing our record of the referenced and changed bits (not the bits in the Linux PTEs, used by the Linux MM subsystem, but the bits used by the KVM_GET_DIRTY_LOG ioctl, and those used by kvm_age_hva() and kvm_test_age_hva()). Signed-off-by: NPaul Mackerras <paulus@samba.org> Signed-off-by: NAlexander Graf <agraf@suse.de>
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