linux-kernel - Re: [PATCH 1/2] iommu/amd: Add HATDis feature support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lpbeiyyzoxuankxzgcms2iwkoydvj2vcpv5jftiy26nkslliwr@juykyxhdwwzv>
Date: Tue, 6 May 2025 05:12:16 +0000
From: Ankit Soni <Ankit.Soni@....com>
To: Joao Martins <joao.m.martins@...cle.com>
CC: <iommu@...ts.linux.dev>, <suravee.suthikulpanit@....com>,
	<joro@...tes.org>, <will@...nel.org>, <robin.murphy@....com>,
	<linux-kernel@...r.kernel.org>, Alejandro Jimenez
	<alejandro.j.jimenez@...cle.com>, David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH 1/2] iommu/amd: Add HATDis feature support

Hi,

On Wed, Apr 30, 2025 at 12:41:04PM +0100, Joao Martins wrote:
> > With intel patch you mentioned above, it seems that it is mostly handling 
> > "second stage translation support" disable, which will eventually disable dma 
> > translation. And in AMD case, HATDis bit indicates host(v1) translation is not
> > available, then attempt to use guest(v2) translation, and if both page
> > table modes are not available then disable dma tranlation.
> 
> OK, I guess it makes sense if HATDis is v1 only.
> 
> My other call out was that when we disable dma-translation all together (aka
> both modes), then we shouldn't advertise the IOMMU groups (internally and to
> userspace) by not calling iommu_device_register()/iommu_device_sysfs_add().
> 
> 	Joao

Sorry for the late reply. I had cross-checked it; if the probe fails,
then IOMMU groups will not be populated, and eventually, it will not
have significance for calling iommu_device_register()/iommu_device_sysfs_add().

-Ankit