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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>, mingo@redhat.com,
        bp@alien8.de, hpa@zytor.com, x86@kernel.org,
        linux-kernel@vger.kernel.org
Cc:     DavidWang@zhaoxin.com, CooperYan@zhaoxin.com,
        QiyuanWang@zhaoxin.com, HerryYang@zhaoxin.com
Subject: Re: [PATCH] x86/cpu: clear X86_BUG_SPECTRE_V2 on Zhaoxin family 7 CPUs
In-Reply-To: <1579075500-7065-1-git-send-email-TonyWWang-oc@zhaoxin.com>
References: <1579075500-7065-1-git-send-email-TonyWWang-oc@zhaoxin.com>
Date:   Wed, 15 Jan 2020 23:19:49 +0100
Message-ID: <87h80wxsze.fsf@nanos.tec.linutronix.de>
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Sender: linux-kernel-owner@vger.kernel.org
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Tony W Wang-oc <TonyWWang-oc@zhaoxin.com> writes:

> These CPUs are not affected by spectre_v2, so clear spectre_v2 bug flag
> in their specific initialization code.
>  
>  	if (cpu_has(c, X86_FEATURE_VMX))
>  		centaur_detect_vmx_virtcap(c);
> +
> +	if (c->x86 == 7) {
> +		setup_clear_cpu_cap(X86_BUG_SPECTRE_V2);
> +		clear_bit(X86_BUG_SPECTRE_V2, (unsigned long *)cpu_caps_set);

No. Please use cpu_vuln_whitelist. It exists for exactly this
purpose. You just need to extend it with a NO_SPECTRE_V2 bit.

Thanks,

        tglx