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From: Joerg Roedel <joro@8bytes.org>
To: Huang Adrian <adrianhuang0701@gmail.com>
Cc: iommu@lists.linux-foundation.org, Adrian Huang <ahuang12@lenovo.com>
Subject: Re: [PATCH 1/1] iommu/amd: Fix the overwritten exclusion range with multiple IVMDs
Date: Tue, 12 Nov 2019 17:05:39 +0100	[thread overview]
Message-ID: <20191112160539.GA3884@8bytes.org> (raw)
In-Reply-To: <CAHKZfL2Zoj-585mHti3_ZAgUNs0s43T=fxGZYt9cKfhQMnUd3w@mail.gmail.com>

On Tue, Nov 12, 2019 at 05:32:31PM +0800, Huang Adrian wrote:
> > On Mon, Nov 11, 2019 at 11:22 PM Joerg Roedel <joro@8bytes.org> wrote:

> > So there are a couple of options here:
> >
> >         1) Bail out and disable the IOMMU as the BIOS screwed up
> >
> >         2) Treat per-device exclusion ranges just as r/w unity-mapped
> >            regions.
> >
> >
> > I think option 2) is the best fix here.
> 
> Yes. This is what this patch does (The first exclusion region still
> uses the exclusion range while the remaining exclusion regions are
> modified to be r/w unity-mapped regions when detecting multiple
> exclusion regions) .

Yeah, but I think it is better to just stop using the exclusion-range
feature of the hardware (because it meand BIOSes are correct) and just
treat every exclusion range (also the first one) as an r/w unity range.

> But, I'm guessing you're talking about that BIOS has to define r/w
> unity-mapped regions instead of the per-device exclusions (Fix from
> BIOS, not prevent the failure from kernel). Right?

That would be best, but I fear this is too much to wish for.

Regards,

	Joerg
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  reply	other threads:[~2019-11-12 16:05 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-04  5:58 [PATCH 1/1] iommu/amd: Fix the overwritten exclusion range with multiple IVMDs Adrian Huang
2019-11-11 15:22 ` Joerg Roedel
2019-11-12  9:32   ` Huang Adrian
2019-11-12 16:05     ` Joerg Roedel [this message]
2019-11-13  1:05       ` Huang Adrian

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