forked from luck/tmp_suning_uos_patched
Revert "KVM/MMU: Flush tlb directly in the kvm_zap_gfn_range()"
This reverts commit 71883a62fc
.
The above commit contains an optimization to kvm_zap_gfn_range which
uses gfn-limited TLB flushes, if enabled. If using these limited flushes,
kvm_zap_gfn_range passes lock_flush_tlb=false to slot_handle_level_range
which creates a race when the function unlocks to call cond_resched.
See an example of this race below:
CPU 0 CPU 1 CPU 3
// zap_direct_gfn_range
mmu_lock()
// *ptep == pte_1
*ptep = 0
if (lock_flush_tlb)
flush_tlbs()
mmu_unlock()
// In invalidate range
// MMU notifier
mmu_lock()
if (pte != 0)
*ptep = 0
flush = true
if (flush)
flush_remote_tlbs()
mmu_unlock()
return
// Host MM reallocates
// page previously
// backing guest memory.
// Guest accesses
// invalid page
// through pte_1
// in its TLB!!
Tested: Ran all kvm-unit-tests on a Intel Haswell machine with and
without this patch. The patch introduced no new failures.
Signed-off-by: Ben Gardon <bgardon@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
parent
71783e09b4
commit
92da008fa2
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@ -5660,13 +5660,8 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
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{
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struct kvm_memslots *slots;
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struct kvm_memory_slot *memslot;
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bool flush_tlb = true;
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bool flush = false;
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int i;
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if (kvm_available_flush_tlb_with_range())
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flush_tlb = false;
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spin_lock(&kvm->mmu_lock);
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for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
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slots = __kvm_memslots(kvm, i);
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@ -5678,17 +5673,12 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
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if (start >= end)
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continue;
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flush |= slot_handle_level_range(kvm, memslot,
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kvm_zap_rmapp, PT_PAGE_TABLE_LEVEL,
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PT_MAX_HUGEPAGE_LEVEL, start,
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end - 1, flush_tlb);
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slot_handle_level_range(kvm, memslot, kvm_zap_rmapp,
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PT_PAGE_TABLE_LEVEL, PT_MAX_HUGEPAGE_LEVEL,
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start, end - 1, true);
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}
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}
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if (flush)
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kvm_flush_remote_tlbs_with_address(kvm, gfn_start,
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gfn_end - gfn_start + 1);
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spin_unlock(&kvm->mmu_lock);
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}
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