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Date: Mon, 30 May 2016 13:49:06 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Christoffer Dall <christoffer.dall@...aro.org>, Marc Zyngier <marc.zyngier@....com> Subject: [PATCH 4.5 08/87] arm/arm64: KVM: Enforce Break-Before-Make on Stage-2 page tables 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marc Zyngier <marc.zyngier@....com> commit d4b9e0790aa764c0b01e18d4e8d33e93ba36d51f upstream. 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. Reported-by: Christoffer Dall <christoffer.dall@...aro.org> Signed-off-by: Marc Zyngier <marc.zyngier@....com> Signed-off-by: Christoffer Dall <christoffer.dall@...aro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- arch/arm/kvm/mmu.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -886,11 +886,14 @@ static int stage2_set_pmd_huge(struct kv 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; } @@ -939,12 +942,14 @@ static int stage2_set_pte(struct kvm *kv /* 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; }
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