Hi,
On 9/26/18 6:32 PM, Suzuki K Poulose wrote:
> Since we are about to remove the lower limit on the IPA size,
> make sure that we do not go to 1 level page table (e.g, with
> 32bit IPA on 64K host with concatenation) to avoid splitting
> the host PMD huge pages at stage2.
>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Cc: Christoffer Dall <cdall@xxxxxxxxxx>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Thanks
Eric
> ---
> Change since v5:
> - Cosmetic changes to the comment
> - Remove unnecessary new line
> ---
> arch/arm64/include/asm/stage2_pgtable.h | 7 ++++++-
> arch/arm64/kvm/reset.c | 10 +++++++++-
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/include/asm/stage2_pgtable.h b/arch/arm64/include/asm/stage2_pgtable.h
> index c62fe118a898..2cce769ba4c6 100644
> --- a/arch/arm64/include/asm/stage2_pgtable.h
> +++ b/arch/arm64/include/asm/stage2_pgtable.h
> @@ -72,8 +72,13 @@
> /*
> * The number of PTRS across all concatenated stage2 tables given by the
> * number of bits resolved at the initial level.
> + * If we force more levels than necessary, we may have (stage2_pgdir_shift > IPA),
> + * in which case, stage2_pgd_ptrs will have one entry.
> */
> -#define __s2_pgd_ptrs(ipa, lvls) (1 << ((ipa) - pt_levels_pgdir_shift((lvls))))
> +#define pgd_ptrs_shift(ipa, pgdir_shift) \
> + ((ipa) > (pgdir_shift) ? ((ipa) - (pgdir_shift)) : 0)
> +#define __s2_pgd_ptrs(ipa, lvls) \
> + (1 << (pgd_ptrs_shift((ipa), pt_levels_pgdir_shift(lvls))))
> #define __s2_pgd_size(ipa, lvls) (__s2_pgd_ptrs((ipa), (lvls)) * sizeof(pgd_t))
>
> #define stage2_pgd_ptrs(kvm) __s2_pgd_ptrs(kvm_phys_shift(kvm), kvm_stage2_levels(kvm))
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index 96b3f50101bc..f156e45760bc 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -190,6 +190,7 @@ int kvm_arm_config_vm(struct kvm *kvm, unsigned long type)
> {
> u64 vtcr = VTCR_EL2_FLAGS;
> u32 parange, phys_shift;
> + u8 lvls;
>
> if (type)
> return -EINVAL;
> @@ -203,7 +204,14 @@ int kvm_arm_config_vm(struct kvm *kvm, unsigned long type)
> if (phys_shift > KVM_PHYS_SHIFT)
> phys_shift = KVM_PHYS_SHIFT;
> vtcr |= VTCR_EL2_T0SZ(phys_shift);
> - vtcr |= VTCR_EL2_LVLS_TO_SL0(stage2_pgtable_levels(phys_shift));
> + /*
> + * Use a minimum 2 level page table to prevent splitting
> + * host PMD huge pages at stage2.
> + */
> + lvls = stage2_pgtable_levels(phys_shift);
> + if (lvls < 2)
> + lvls = 2;
> + vtcr |= VTCR_EL2_LVLS_TO_SL0(lvls);
>
> /*
> * Enable the Hardware Access Flag management, unconditionally
>
