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Message-ID: <4cfa1f1827e0ccbfbc94de3beba64a4a141b2248.camel@linux.intel.com>
Subject: Re: [PATCH v2] iommu/vt-d: avoid unnecessory panic if iommu init
 fail in tboot system
From:   Lukasz Hawrylko <lukasz.hawrylko@linux.intel.com>
To:     Zhenzhong Duan <zhenzhong.duan@gmail.com>,
        linux-kernel@vger.kernel.org
Cc:     ning.sun@intel.com, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, x86@kernel.org, dwmw2@infradead.org,
        baolu.lu@linux.intel.com, joro@8bytes.org,
        iommu@lists.linux-foundation.org, tboot-devel@lists.sourceforge.net
Date:   Tue, 10 Nov 2020 16:53:33 +0100
In-Reply-To: <20201110071908.3133-1-zhenzhong.duan@gmail.com>
References: <20201110071908.3133-1-zhenzhong.duan@gmail.com>
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Hi Zhenzhong

On Tue, 2020-11-10 at 15:19 +0800, Zhenzhong Duan wrote:
> "intel_iommu=off" command line is used to disable iommu but iommu is force
> enabled in a tboot system for security reason.
> 
> However for better performance on high speed network device, a new option
> "intel_iommu=tboot_noforce" is introduced to disable the force on.
> 
> By default kernel should panic if iommu init fail in tboot for security
> reason, but it's unnecessory if we use "intel_iommu=tboot_noforce,off".
> 
> Fix the code setting force_on and move intel_iommu_tboot_noforce
> from tboot code to intel iommu code.
> 
> Fixes: 7304e8f28bb2 ("iommu/vt-d: Correctly disable Intel IOMMU force on")
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
> ---
> v2: move ckeck of intel_iommu_tboot_noforce into iommu code per Baolu.

I have check it on my TXT testing environment with latest TBOOT,
everything works as expected.

Thanks,
Lukasz