linux-kernel - Re: [PATCH] iommu/amd: flush not present cache in iommu_map

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Message-ID: <20190424155505.GA6731@8bytes.org>
Date:   Wed, 24 Apr 2019 17:55:06 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Tom Murphy <tmurphy@...sta.com>, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, Tom Murphy <murphyt7@....ie>
Subject: Re: [PATCH] iommu/amd: flush not present cache in iommu_map_page

On Wed, Apr 24, 2019 at 07:58:19AM -0700, Christoph Hellwig wrote:
> I'd be tempted to do that.  But lets just ask Joerg if he has
> any opinion..

The reason was that it is an unlikely path, as hardware implementations
are not allowed to set this bit. It is purely for emulated AMD IOMMUs.
I have not measured whether this annotation has any performance
benefit, but I find it more readable at least.

Regards,

	Joerg

PS: Why did you drop me from the Cc list of the previous replies?