On Thursday 15 Jul 2021 at 17:31:47 (+0100), Marc Zyngier wrote:
> +struct s2_walk_data {
> + kvm_pte_t pteval;
> + u32 level;
> +};
> +
> +static int s2_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
> + enum kvm_pgtable_walk_flags flag, void * const arg)
> +{
> + struct s2_walk_data *data = arg;
> +
> + data->level = level;
> + data->pteval = *ptep;
> + return 0;
> +}
> +
> +/* Assumes mmu_lock taken */
> +static bool __check_ioguard_page(struct kvm_vcpu *vcpu, gpa_t ipa)
> +{
> + struct s2_walk_data data;
> + struct kvm_pgtable_walker walker = {
> + .cb = s2_walker,
> + .flags = KVM_PGTABLE_WALK_LEAF,
> + .arg = &data,
> + };
> +
> + kvm_pgtable_walk(vcpu->arch.hw_mmu->pgt, ALIGN_DOWN(ipa, PAGE_SIZE),
> + PAGE_SIZE, &walker);
> +
> + /* Must be a PAGE_SIZE mapping with our annotation */
> + return (BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(data.level)) == PAGE_SIZE &&
> + data.pteval == MMIO_NOTE);
Nit: you could do this check in the walker directly and check the return
value of kvm_pgtable_walk() instead. That would allow to get rid of
struct s2_walk_data.
Also, though the compiler might be able to optimize, maybe simplify the
level check to level == (KVM_PGTABLE_MAX_LEVELS - 1)?
Thanks,
Quentin
> +}
