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:   Wed, 21 Jun 2023 11:36:53 -0700
From:   Breno Leitao <leitao@debian.org>
To:     Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@kernel.org>, leit@fb.com,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] x86/bugs: Break down mitigations configurations
Message-ID: <ZJNDRSUZuZ2L+pwo@gmail.com>
References: <20230616164851.2559415-1-leitao@debian.org>
 <20230621001327.qdyebewnx7r5aiy3@desk>
 <ZJMdKUr98H8zPSAl@gmail.com>
 <20230621173135.wiprtgzslhw5z5or@desk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230621173135.wiprtgzslhw5z5or@desk>
Precedence: bulk

On Wed, Jun 21, 2023 at 10:31:35AM -0700, Pawan Gupta wrote:
> On Wed, Jun 21, 2023 at 08:54:17AM -0700, Breno Leitao wrote:
> > On Tue, Jun 20, 2023 at 05:13:27PM -0700, Pawan Gupta wrote:
> > > On Fri, Jun 16, 2023 at 09:48:50AM -0700, Breno Leitao wrote:
> > > > There is no way to disable MDS, TAA, MMIO Stale data mitigation today at
> > > > compilation time. These mitigations are enabled even if
> > > > CONFIG_SPECULATION_MITIGATIONS is unset.
> > > > 
> > > > Create a new KCONFIG option for each mitigation under
> > > > CONFIG_SPECULATION_MITIGATIONS that allows these
> > > > mitigations to be disabled by default at compilation time.
> > > 
> > > I don't think all mitigations are still controllable at build-time e.g.
> > > spectre_v2 eIBRS mitigation will still be deployed irrespective of the
> > > config.
> > 
> > Right. This patchset only cares about MDS, TAA and MMIO. I am more than
> > happy to send a new patch to also disable spectre_v2 eIBRS.
> 
> What about Retbleed, L1TF, SRBDS etc? I thought the goal is to control
> all speculation mitigations?
> 
> To be consistent CONFIG_SPECULATION_MITIGATIONS should control all
> speculation mitigations.

If I understand where you want to go, you think we should create a
single patchset that creates a CONFIG_<MITIGATION> for each mitigation,
and move get it under CONFIG_SPECULATION_MITIGATIONS.

Is this what you think we should do?

Thanks!