On Thu, Apr 28, 2016 at 04:16:31PM +0100, Marc Zyngier wrote:
> 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.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
FWIW, this looks correct to me.
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Mark.
> ---
> arch/arm/kvm/mmu.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 58dbd5c..edf1cd1 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -893,11 +893,14 @@ 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;
> }
>
> @@ -946,12 +949,14 @@ 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;
> }
>
> --
> 2.1.4
>
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