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

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Alexander Potapenko <glider@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Kostya Serebryany <kcc@google.com>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	"H . J . Lu" <hjl.tools@gmail.com>,
	Andi Kleen <ak@linux.intel.com>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv3 4/8] x86/mm: Handle LAM on context switch
Date: Sat, 18 Jun 2022 01:39:38 +0300	[thread overview]
Message-ID: <20220617223938.3qeb7tjr7wdjas27@black.fi.intel.com> (raw)
In-Reply-To: <CAG_fn=U4hETfYrRbZMJ2xEEgP+FzWmYX+u+Kr=x0NkytU6nGfg@mail.gmail.com>

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@linux.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@linux.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