Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <8be4a3c08fce8c47f7d7e42c6d5b6c854a39995c.camel@kernel.crashing.org>
Subject: Re: [PATCH v2 3/4] arch/x86: Optionally flush L1D on context switch
From:   Benjamin Herrenschmidt <benh@kernel.crashing.org>
To:     Kees Cook <keescook@chromium.org>, Balbir Singh <sblbir@amazon.com>
Cc:     tglx@linutronix.de, linux-kernel@vger.kernel.org,
        jpoimboe@redhat.com, tony.luck@intel.com, x86@kernel.org,
        dave.hansen@intel.com
Date:   Wed, 08 Apr 2020 09:37:04 +1000
In-Reply-To: <202004071125.605F665@keescook>
References: <20200406031946.11815-1-sblbir@amazon.com>
         <20200406031946.11815-4-sblbir@amazon.com> <202004071125.605F665@keescook>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, 2020-04-07 at 11:26 -0700, Kees Cook wrote:
> > Add arch specific prctl()'s to opt-in to the L1D cache on context
> > switch
> > out, the existing mechanisms of tracking prev_mm via cpu_tlbstate
> > is
> > reused. cond_ibpb() is refactored and renamed into
> > cond_mitigation().
> 
> I still think this should be a generic prctl(). If there is a strong
> reason not to do this, can it be described in the commit log here?

Agreed.

Cheers,
Ben.