3.16.37-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Marc Zyngier <[email protected]> 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 <[email protected]> Signed-off-by: Marc Zyngier <[email protected]> Signed-off-by: Christoffer Dall <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- 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 @@ -682,11 +682,14 @@ 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; } @@ -723,12 +726,14 @@ 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; }
