linux-kernel - Re: [PATCH v4 12/12] x86/traps: Fix up invalid PASID

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Date:   Fri, 26 Jun 2020 11:44:50 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Fenghua Yu <fenghua.yu@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Joerg Roedel <joro@...tes.org>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, H Peter Anvin <hpa@...or.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Christoph Hellwig <hch@...radeed.org>,
        Ashok Raj <ashok.raj@...el.com>,
        Jacob Jun Pan <jacob.jun.pan@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        x86 <x86@...nel.org>, iommu@...ts.linux-foundation.org
Subject: Re: [PATCH v4 12/12] x86/traps: Fix up invalid PASID

On Thu, Jun 25, 2020 at 01:17:22PM -0700, Fenghua Yu wrote:

> +static bool fixup_pasid_exception(void)
> +{
> +	if (!IS_ENABLED(CONFIG_INTEL_IOMMU_SVM))
> +		return false;
> +	if (!static_cpu_has(X86_FEATURE_ENQCMD))
> +		return false;

elsewhere you had another variation:

+       if (!IS_ENABLED(CONFIG_INTEL_IOMMU_SVM))
+               return;
+
+       if (!cpu_feature_enabled(X86_FEATURE_ENQCMD))
+               return;

Which is it, and why do we need the CONFIG thing when combined with the
enabled thing?