linux-kernel - Re: [PATCH] iommu/vt-d: Flush old iotlb for kdump when the device gets context mapped

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Date:   Tue, 29 Nov 2016 15:35:47 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     xlpang@...hat.com
Cc:     Myron Stowe <myron.stowe@...il.com>,
        iommu@...ts.linux-foundation.org,
        Don Brace <don.brace@...rosemi.com>,
        Dave Young <dyoung@...hat.com>, kexec@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        Myron Stowe <myron.stowe@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH] iommu/vt-d: Flush old iotlb for kdump when the device
 gets context mapped

On Thu, Nov 17, 2016 at 10:47:28AM +0800, Xunlei Pang wrote:
> As per the comment, the code here only needs to flush context caches
> for the special domain 0 which is used to tag the
> non-present/erroneous caches, seems we should flush the old domain id
> of present entries for kdump according to the analysis, other than the
> new-allocated domain id. Let me ponder more on this.

Flushing the context entry only is fine. The old domain-id will not be
re-used anyway, so there is no point in reading it out of the context
table and flush it.

Also, please add a Fixes-tag when you re-post this patch.


	Joerg