Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 16 Jun 2022 19:40:12 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>, x86@kernel.org,
        Kostya Serebryany <kcc@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Alexander Potapenko <glider@google.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-mm@kvack.org, linux-kernel@vger.kernel.org, namit@vmware.com
Subject: Re: [PATCHv3 4/8] x86/mm: Handle LAM on context switch
Message-ID: <20220616164012.uuok46yozncbwe7u@black.fi.intel.com>
References: <20220610143527.22974-1-kirill.shutemov@linux.intel.com>
 <20220610143527.22974-5-kirill.shutemov@linux.intel.com>
 <Yqry9+efzp6lml89@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Yqry9+efzp6lml89@hirez.programming.kicks-ass.net>
Precedence: bulk

On Thu, Jun 16, 2022 at 11:08:07AM +0200, Peter Zijlstra wrote:
> Either use that one spare byte, or find room elsewhere I suppose.

Okay, I will put into the byte after invalidate_other and modify
tlbstate_lam_cr3_mask() and set_tlbstate_lam_cr3_mask() to shift it
accordingly.

It looks like this:

struct tlb_state {
	struct mm_struct *         loaded_mm;            /*     0     8 */
	union {
		struct mm_struct * last_user_mm;         /*     8     8 */
		unsigned long      last_user_mm_spec;    /*     8     8 */
	};                                               /*     8     8 */
	union {
		struct mm_struct *         last_user_mm;         /*     0     8 */
		unsigned long              last_user_mm_spec;    /*     0     8 */
	};

	u16                        loaded_mm_asid;       /*    16     2 */
	u16                        next_asid;            /*    18     2 */
	bool                       invalidate_other;     /*    20     1 */
	u8                         lam;                  /*    21     1 */
	unsigned short             user_pcid_flush_mask; /*    22     2 */
	unsigned long              cr4;                  /*    24     8 */
	struct tlb_context         ctxs[6];              /*    32    96 */

	/* size: 128, cachelines: 2, members: 9 */
};

-- 
 Kirill A. Shutemov