From: Andrew Cooper <andrew.cooper3@citrix.com>
To: "Zhang, Yang Z" <yang.z.zhang@intel.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "Tim Deegan (tim@xen.org)" <tim@xen.org>,
"'Jan Beulich (JBeulich@suse.com)'" <JBeulich@suse.com>,
"Zhang, Xiantao" <xiantao.zhang@intel.com>
Subject: Re: question on share ept page table with vtd
Date: Sat, 1 Feb 2014 00:56:48 +0000 [thread overview]
Message-ID: <52EC4650.7020302@citrix.com> (raw)
In-Reply-To: <A9667DDFB95DB7438FA9D7D576C3D87E0A9CCC9C@SHSMSX104.ccr.corp.intel.com>
On 01/02/2014 00:29, Zhang, Yang Z wrote:
> Hi all
>
> I have a question with the page table share between EPT and VTD which is enabled by default. Currently, we will enable log_dirty mode to track vram. And when first enable the log dirty mode, it will set all guest ram to readonly in EPT entry. The question is that if a page is current used as DMA write buffer, isn't it a problem?
>
> best regards
> yang
Looking at the code, it would indeed appear to be a problem.
Is has presumably gone unnoticed until now as all writes into the vram
would have been from software, and hit the log_dirty logic, rather than
DMA writes hitting the IOMMU.
~Andrew
next prev parent reply other threads:[~2014-02-01 0:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-01 0:29 question on share ept page table with vtd Zhang, Yang Z
2014-02-01 0:56 ` Andrew Cooper [this message]
2014-02-01 1:13 ` Zhang, Yang Z
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