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arm/arm64: KVM: Enforce Break-Before-Make on Stage-2 page tables 

The ARM architecture mandates that when changing a page table entry
from a valid entry to another valid entry, an invalid entry is first
written, TLB invalidated, and only then the new entry being written.

The current code doesn't respect this, directly writing the new
entry and only then invalidating TLBs. Let's fix it up.

Cc: <stable@vger.kernel.org>
Reported-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
hifive-unleashed-5.1
Marc Zyngier 2016-04-28 16:16:31 +01:00 committed by Christoffer Dall
parent 02e0b7600f
commit d4b9e0790a
1 changed files with 11 additions and 6 deletions
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17
arch/arm/kvm/mmu.c
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@ -910,11 +910,14 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
VM_BUG_ON(pmd_present(*pmd) && pmd_pfn(*pmd) != pmd_pfn(*new_pmd));
old_pmd = *pmd;
kvm_set_pmd(pmd, *new_pmd);
if (pmd_present(old_pmd))
if (pmd_present(old_pmd)) {
pmd_clear(pmd);
kvm_tlb_flush_vmid_ipa(kvm, addr);
else
} else {
get_page(virt_to_page(pmd));
}
kvm_set_pmd(pmd, *new_pmd);
return 0;
}
@ -963,12 +966,14 @@ static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
/* Create 2nd stage page table mapping - Level 3 */
old_pte = *pte;
kvm_set_pte(pte, *new_pte);
if (pte_present(old_pte))
if (pte_present(old_pte)) {
kvm_set_pte(pte, __pte(0));
kvm_tlb_flush_vmid_ipa(kvm, addr);
else
} else {
get_page(virt_to_page(pte));
}
kvm_set_pte(pte, *new_pte);
return 0;
}