linux-kernel - Re: [PATCHv3 4/8] x86/mm: Handle LAM on context switch

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Message-ID: <20220617223938.3qeb7tjr7wdjas27@black.fi.intel.com>
Date:   Sat, 18 Jun 2022 01:39:38 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Kostya Serebryany <kcc@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        "H . J . Lu" <hjl.tools@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 4/8] x86/mm: Handle LAM on context switch

On Fri, Jun 17, 2022 at 05:35:05PM +0200, Alexander Potapenko wrote:
> On Fri, Jun 10, 2022 at 4:35 PM Kirill A. Shutemov
> <kirill.shutemov@...ux.intel.com> wrote:
> >
> > Linear Address Masking mode for userspace pointers encoded in CR3 bits.
> > The mode is selected per-thread. Add new thread features indicate that the
> > thread has Linear Address Masking enabled.
> >
> > switch_mm_irqs_off() now respects these flags and constructs CR3
> > accordingly.
> >
> > The active LAM mode gets recorded in the tlb_state.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> 
> 
> > +#ifdef CONFIG_X86_64
> > +static inline u64 mm_cr3_lam_mask(struct mm_struct *mm)
> > +{
> > +       return mm->context.lam_cr3_mask;
> > +}
> 
> Nit: can we have either "cr3_lam_mask" or "lam_cr3_mask" in both places?

With changes sugessted by Peter, the field in the mmu_context will be
called 'lam' as it is not CR3 mask anymore.

-- 
 Kirill A. Shutemov