Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200616074934.1600036-1-keescook@chromium.org> <20200616074934.1600036-7-keescook@chromium.org>
In-Reply-To: <20200616074934.1600036-7-keescook@chromium.org>
From:   Andy Lutomirski <luto@kernel.org>
Date:   Tue, 16 Jun 2020 09:59:29 -0700
Message-ID: <CALCETrVSnLAkWN_b7rNY1mbF16qXavbXYtv9fVZA-Q4ZVnTXhQ@mail.gmail.com>
Subject: Re: [PATCH 6/8] x86: Provide API for local kernel TLB flushing
To:     Kees Cook <keescook@chromium.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Christian Brauner <christian@brauner.io>,
        Sargun Dhillon <sargun@sargun.me>,
        Tycho Andersen <tycho@tycho.ws>, Jann Horn <jannh@google.com>,
        "zhujianwei (C)" <zhujianwei7@huawei.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Matthew Wilcox <willy@infradead.org>,
        Andy Lutomirski <luto@kernel.org>,
        Will Drewry <wad@chromium.org>, Shuah Khan <shuah@kernel.org>,
        Matt Denton <mpdenton@google.com>,
        Chris Palmer <palmer@google.com>,
        Jeffrey Vander Stoep <jeffv@google.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Hehuazhen <hehuazhen@huawei.com>, X86 ML <x86@kernel.org>,
        Linux Containers <containers@lists.linux-foundation.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Jun 16, 2020 at 12:49 AM Kees Cook <keescook@chromium.org> wrote:
>
> The seccomp constant action bitmap filter evaluation routine depends
> on being able to quickly clear the PTE "accessed" bit for a temporary
> allocation. Provide access to the existing CPU-local kernel memory TLB
> flushing routines.

Can you write a better justification?  Also, unless I'm just
incompetent this morning, I can't find anyone calling this in the
series.