From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Kaushik Kumar Ram <kaushik@rice.edu>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: question on iommu _map_page
Date: Fri, 11 Jun 2010 09:32:50 +0100 [thread overview]
Message-ID: <C837B342.17533%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <C0DB17AF-42E4-4AB6-9A5E-E7D2B9DC5A96@rice.edu>
On 10/06/2010 22:59, "Kaushik Kumar Ram" <kaushik@rice.edu> wrote:
>> Actually I've implemented the better fix as xen-unstable:21476. Hope that
>> works okay for you.
>
>
> Checking if act->pin is zero before calling iommu_unmap_page() (in
> grant_table.c) is not sufficient since there can be multiple
> active grants all referring to the same mfn. In fact I came across iommu page
> faults because pages were
> getting unmapped from the IOMMU when active grants referring to these pages
> were still around.
> Ideally, there needs to be a per-page count of how many IOMMU mappings exists
> for a page.
> I can't think of an obvious fix for this problem. For my purposes, I hacked
> page_info to add another counter which I guess is not an acceptable solution!
See if xen-unstable:21597 works for you.
-- Keir
next prev parent reply other threads:[~2010-06-11 8:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-27 20:37 question on iommu _map_page Kaushik Kumar Ram
2010-05-27 20:46 ` Keir Fraser
2010-05-27 20:59 ` Kaushik Kumar Ram
2010-05-28 8:08 ` Keir Fraser
2010-05-28 23:20 ` Kaushik Kumar Ram
2010-05-29 7:29 ` Keir Fraser
2010-05-29 8:08 ` Kaushik Kumar Ram
2010-06-10 21:59 ` Kaushik Kumar Ram
2010-06-11 8:32 ` Keir Fraser [this message]
2010-07-02 6:22 ` Kaushik Kumar Ram
2010-07-02 7:13 ` Keir Fraser
2010-07-02 10:41 ` Keir Fraser
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