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From:   Andy Lutomirski <luto@kernel.org>
Date:   Wed, 17 Jan 2018 15:41:07 -0800
Message-ID: <CALCETrWDiXxuUSS4jF7=tNtCYyQX7bSHQLF76bAd_whz1zPcjw@mail.gmail.com>
Subject: Re: [PATCH 14/16] x86/mm/legacy: Populate the user page-table with
 user pgd's
To:     Joerg Roedel <joro@8bytes.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        "H . Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Juergen Gross <jgross@suse.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Brian Gerst <brgerst@gmail.com>,
        David Laight <David.Laight@aculab.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Eduardo Valentin <eduval@amazon.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        Will Deacon <will.deacon@arm.com>,
        "Liguori, Anthony" <aliguori@amazon.com>,
        Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
        Hugh Dickins <hughd@google.com>,
        Kees Cook <keescook@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Waiman Long <llong@redhat.com>, Joerg Roedel <jroedel@suse.de>
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On Tue, Jan 16, 2018 at 8:36 AM, Joerg Roedel <joro@8bytes.org> wrote:
> From: Joerg Roedel <jroedel@suse.de>
>
> Also populate the user-spage pgd's in the user page-table.
>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
>  arch/x86/include/asm/pgtable-2level.h | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/include/asm/pgtable-2level.h b/arch/x86/include/asm/pgtable-2level.h
> index 685ffe8a0eaf..d96486d23c58 100644
> --- a/arch/x86/include/asm/pgtable-2level.h
> +++ b/arch/x86/include/asm/pgtable-2level.h
> @@ -19,6 +19,9 @@ static inline void native_set_pte(pte_t *ptep , pte_t pte)
>
>  static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
>  {
> +#ifdef CONFIG_PAGE_TABLE_ISOLATION
> +       pmd.pud.p4d.pgd = pti_set_user_pgd(&pmdp->pud.p4d.pgd, pmd.pud.p4d.pgd);
> +#endif
>         *pmdp = pmd;
>  }
>

Nothing against your patch, but this seems like a perfectly fine place
to rant: I *hate* the way we deal with page table folding.  Grr.