forked from luck/tmp_suning_uos_patched
KVM: x86/mmu: Use -1 to flag an undefined spte in get_mmio_spte()
commit 2aa078932ff6c66bf10cc5b3144440dbfa7d813d upstream.
Return -1 from the get_walk() helpers if the shadow walk doesn't fill at
least one spte, which can theoretically happen if the walk hits a
not-present PDPTR. Returning the root level in such a case will cause
get_mmio_spte() to return garbage (uninitialized stack data). In
practice, such a scenario should be impossible as KVM shouldn't get a
reserved-bit page fault with a not-present PDPTR.
Note, using mmu->root_level in get_walk() is wrong for other reasons,
too, but that's now a moot point.
Fixes: 95fb5b0258
("kvm: x86/mmu: Support MMIO in the TDP MMU")
Cc: Ben Gardon <bgardon@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20201218003139.2167891-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
23220e87c9
commit
afd621673f
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@ -3488,7 +3488,7 @@ static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct)
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static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes)
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{
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struct kvm_shadow_walk_iterator iterator;
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int leaf = vcpu->arch.mmu->root_level;
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int leaf = -1;
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u64 spte;
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@ -3532,6 +3532,11 @@ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep)
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else
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leaf = get_walk(vcpu, addr, sptes);
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if (unlikely(leaf < 0)) {
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*sptep = 0ull;
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return reserved;
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}
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rsvd_check = &vcpu->arch.mmu->shadow_zero_check;
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for (level = root; level >= leaf; level--) {
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@ -1152,8 +1152,8 @@ int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes)
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{
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struct tdp_iter iter;
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struct kvm_mmu *mmu = vcpu->arch.mmu;
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int leaf = vcpu->arch.mmu->shadow_root_level;
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gfn_t gfn = addr >> PAGE_SHIFT;
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int leaf = -1;
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tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) {
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leaf = iter.level;
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