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

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Date:   Fri, 9 Feb 2018 17:48:36 +0000
From:   Andy Lutomirski <luto@...nel.org>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>, Jiri Kosina <jkosina@...e.cz>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Brian Gerst <brgerst@...il.com>,
        David Laight <David.Laight@...lab.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Eduardo Valentin <eduval@...zon.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Will Deacon <will.deacon@....com>,
        "Liguori, Anthony" <aliguori@...zon.com>,
        Daniel Gruss <daniel.gruss@...k.tugraz.at>,
        Hugh Dickins <hughd@...gle.com>,
        Kees Cook <keescook@...gle.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Waiman Long <llong@...hat.com>, Pavel Machek <pavel@....cz>,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 20/31] x86/mm/pae: Populate the user page-table with user pgd's

On Fri, Feb 9, 2018 at 9:25 AM, Joerg Roedel <joro@...tes.org> wrote:
> From: Joerg Roedel <jroedel@...e.de>
>
> When we populate a PGD entry, make sure we populate it in
> the user page-table too.
>
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>  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.