Hi Marc,
On Mon, Nov 29, 2021 at 08:00:46PM +0000, Marc Zyngier wrote:
> The S2 page table code has a limited use the SW bits, but we are about
> to need them to encode some guest Stage-2 information (its mapping size
> in the form of the TTL encoding).
>
> Propagate the SW bits specified by the caller, and store them into
> the corresponding entry.
>
> Signed-off-by: Marc Zyngier <m...@kernel.org>
> ---
> arch/arm64/kvm/hyp/pgtable.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 8cdbc43fa651..d69e400b2de6 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -1064,9 +1064,6 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable
> *pgt, u64 addr,
> u32 level;
> kvm_pte_t set = 0, clr = 0;
>
> - if (prot & KVM_PTE_LEAF_ATTR_HI_SW)
> - return -EINVAL;
> -
> if (prot & KVM_PGTABLE_PROT_R)
> set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R;
>
> @@ -1076,6 +1073,10 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable
> *pgt, u64 addr,
> if (prot & KVM_PGTABLE_PROT_X)
> clr |= KVM_PTE_LEAF_ATTR_HI_S2_XN;
>
> + /* Always propagate the SW bits */
> + clr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_HI_SW, 0xf);
Nitpick: isn't that the same as:
clr |= KVM_PTE_LEAF_ATTR_HI_SW;
which looks more readable to me.
> + set |= prot & KVM_PTE_LEAF_ATTR_HI_SW;
Checked stage2_attr_walker() callbak, first it clears the bits in clr, then
sets the bits in set, so this looks correct to me:
Reviewed-by: Alexandru Elisei <alexandru.eli...@arm.com>
Thanks,
Alex
> +
> ret = stage2_update_leaf_attrs(pgt, addr, 1, set, clr, NULL, &level);
> if (!ret)
> kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, pgt->mmu, addr, level);
> --
> 2.30.2
>
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