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authorBen Gardon <bgardon@google.com>2021-01-07 01:19:34 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2021-01-08 00:11:31 +0100
commita889ea54b3daa63ee1463dc19ed699407d61458b (patch)
tree5f2b41f8c8b04523e628a4599aaa46df9c2e468d /drivers/md/md-cluster.c
parentkvm: check tlbs_dirty directly (diff)
downloadlinux-a889ea54b3daa63ee1463dc19ed699407d61458b.tar.xz
linux-a889ea54b3daa63ee1463dc19ed699407d61458b.zip
KVM: x86/mmu: Ensure TDP MMU roots are freed after yield
Many TDP MMU functions which need to perform some action on all TDP MMU roots hold a reference on that root so that they can safely drop the MMU lock in order to yield to other threads. However, when releasing the reference on the root, there is a bug: the root will not be freed even if its reference count (root_count) is reduced to 0. To simplify acquiring and releasing references on TDP MMU root pages, and to ensure that these roots are properly freed, move the get/put operations into another TDP MMU root iterator macro. Moving the get/put operations into an iterator macro also helps simplify control flow when a root does need to be freed. Note that using the list_for_each_entry_safe macro would not have been appropriate in this situation because it could keep a pointer to the next root across an MMU lock release + reacquire, during which time that root could be freed. Reported-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Fixes: faaf05b00aec ("kvm: x86/mmu: Support zapping SPTEs in the TDP MMU") Fixes: 063afacd8730 ("kvm: x86/mmu: Support invalidate range MMU notifier for TDP MMU") Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU") Fixes: 14881998566d ("kvm: x86/mmu: Support disabling dirty logging for the tdp MMU") Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20210107001935.3732070-1-bgardon@google.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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