Re: [PATCH 20/31] x86/mm/pae: Populate the user page-table with user pgd's

[Andy Lutomirski]

On Fri, Feb 9, 2018 at 9:25 AM, Joerg Roedel <joro@xxxxxxxxxx> wrote:
> From: Joerg Roedel <jroedel@xxxxxxx>
>
> When we populate a PGD entry, make sure we populate it in
> the user page-table too.
>
> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
> ---
>  arch/x86/include/asm/pgtable-3level.h | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
> index bc4af54..1a0661b 100644
> --- a/arch/x86/include/asm/pgtable-3level.h
> +++ b/arch/x86/include/asm/pgtable-3level.h
> @@ -98,6 +98,9 @@ static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
>
>  static inline void native_set_pud(pud_t *pudp, pud_t pud)
>  {
> +#ifdef CONFIG_PAGE_TABLE_ISOLATION
> +       pud.p4d.pgd = pti_set_user_pgd(&pudp->p4d.pgd, pud.p4d.pgd);
> +#endif
>         set_64bit((unsigned long long *)(pudp), native_pud_val(pud));
>  }
>
> @@ -194,6 +197,10 @@ static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
>  {
>         union split_pud res, *orig = (union split_pud *)pudp;
>
> +#ifdef CONFIG_PAGE_TABLE_ISOLATION
> +       pti_set_user_pgd(&pudp->p4d.pgd, __pgd(0));
> +#endif
> +
>         /* xchg acts as a barrier before setting of the high bits */
>         res.pud_low = xchg(&orig->pud_low, 0);
>         res.pud_high = orig->pud_high;

Can you rename the helper from pti_set_user_pgd() to
pti_set_user_top_level_entry() or similar?  The name was already a bit
absurd, but now it's just nuts.