linux-kernel - Re: [PATCH v3] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode

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Message-ID: <e7bc00fc-fe53-800e-8439-f1fbdca5dd26@redhat.com>
Date:   Thu, 2 Jul 2020 20:17:57 -0400
From:   Waiman Long <longman@...hat.com>
To:     Abhishek Bhardwaj <abhishekbh@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     Anthony Steinhauser <asteinhauser@...gle.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tony Luck <tony.luck@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>, kvm@...r.kernel.org,
        x86@...nel.org
Subject: Re: [PATCH v3] x86/speculation/l1tf: Add KConfig for setting the L1D
 cache flush mode

On 7/2/20 6:12 PM, Abhishek Bhardwaj wrote:
> This change adds a new kernel configuration that sets the l1d cache
> flush setting at compile time rather than at run time.
>
> Signed-off-by: Abhishek Bhardwaj <abhishekbh@...gle.com>

Can you explain in the commit log why you need a compile time option 
whereas the desired mitigation can also be set via a boot command line 
option?

The code looks OK, but the question I have is why.

Cheers,
Longman