From: Joerg Roedel <joro@8bytes.org>
To: Wan Zongshun <vw@iommu.org>
Cc: iommu@lists.linux-foundation.org, Joerg Roedel <jroedel@suse.de>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] iommu/amd: Fix unity mapping initialization race
Date: Mon, 11 Jul 2016 09:19:59 +0200 [thread overview]
Message-ID: <20160711071959.GB12639@8bytes.org> (raw)
In-Reply-To: <57823445.1020808@iommu.org>
On Sun, Jul 10, 2016 at 07:40:53PM +0800, Wan Zongshun wrote:
> Do you mean we need enable the V and TV bits to DTE entry after all
> DTEs tables were initialized completely?
Yes, this is what my patch does and what fixes the bug that was
reported on machines which have unity-mapping entries.
> I checked this function 'init_device_table_dma', and find it just set
> V and TV bit, to set translation info valid and DTE bits127:1 valid.
Right, if no other bits are set this blocks all DMA from the gives
device-id.
> So I just think all things it should to do are to allow DMA access,
> GPA-to-SPA translation should be active, why you add function
> comments below is to not allow DMA access and suppress all page
> faults?
>
> /*
> * Init the device table to not allow DMA access for devices and
> * suppress all page faults
> */
Yeah, that comment needs to be updated. Not all DMA is blocked and
page-faults are not suppressed at all. Thanks for noticing.
Joerg
next prev parent reply other threads:[~2016-07-11 7:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-06 16:00 [PATCH] iommu/amd: Fix unity mapping initialization race Joerg Roedel
2016-07-10 11:40 ` Wan Zongshun
2016-07-11 7:19 ` Joerg Roedel [this message]
2016-07-11 9:25 ` Wan Zongshun
2016-07-11 9:39 ` Joerg Roedel
2016-07-11 10:05 ` Wan ZongShun
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