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KVM: x86/mmu: WARN if old _or_ new SPTE is REMOVED in non-atomic path

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WARN if the new_spte being set by __tdp_mmu_set_spte() is a REMOVED_SPTE,
which is called out by the comment as being disallowed but not actually
checked.  Keep the WARN on the old_spte as well, because overwriting a
REMOVED_SPTE in the non-atomic path is also disallowed (as evidence by
lack of splats with the existing WARN).

Fixes: 08f07c800e9d ("KVM: x86/mmu: Flush TLBs after zap in TDP MMU PF handler")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-12-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-02-26 00:15:29 +00:00 committed by Paolo Bonzini
parent 0e587aa733
commit 966da62ada
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kvm/mmu/tdp_mmu.c
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@ -626,13 +626,13 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
lockdep_assert_held_write(&kvm->mmu_lock);
/*
* No thread should be using this function to set SPTEs to the
* No thread should be using this function to set SPTEs to or from the
* temporary removed SPTE value.
* If operating under the MMU lock in read mode, tdp_mmu_set_spte_atomic
* should be used. If operating under the MMU lock in write mode, the
* use of the removed SPTE should not be necessary.
*/
WARN_ON(is_removed_spte(iter->old_spte));
WARN_ON(is_removed_spte(iter->old_spte) || is_removed_spte(new_spte));
kvm_tdp_mmu_write_spte(iter->sptep, new_spte);