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From: Joe Jin <joe.jin@oracle.com>
To: Dongli Zhang <dongli.zhang@oracle.com>
Cc: Christoph Helwig <hch@lst.de>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	konrad@kernel.org, John Sobecki <john.sobecki@oracle.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] xen-swiotlb: exchange memory with Xen only when pages are contiguous
Date: Fri, 26 Oct 2018 07:48:09 -0700	[thread overview]
Message-ID: <dac26047-7426-fec5-0360-fbfd6e211d69@oracle.com> (raw)
In-Reply-To: <10301c25-5bbf-51b6-6cb2-77e30bcd9a99@oracle.com>

On 10/26/18 1:54 AM, Dongli Zhang wrote:
> If dom0 (or any domain) is happy, although it could try to exchange all its
> continuous dma pages back to xen hypervisor. From the perspective of each
> domain, they always would like to keep as much continuous dma page as possible.
> 
> I am thinking something different. If there is malicious domU keep exchanging
> memory and allocating continuous pages from xen hypervisor, will the
> continuously dma pages be used up (sort of DoS attack)?

This is a problem.

> 
> I am not sure if there is anything in xen hypervisor to prevent such behavior?

I'm not sure but I guess it hard to prevent it, xen hypervisor could not identify
if the requirement is reasonable or no.

Maybe Xen reserve some low memory for guest start?

Thanks,
Joe

  reply	other threads:[~2018-10-26 14:48 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-24  3:09 Joe Jin
2018-10-24 13:02 ` Konrad Rzeszutek Wilk
2018-10-24 13:57   ` Boris Ostrovsky
2018-10-24 14:43     ` Joe Jin
2018-10-25 11:45       ` Boris Ostrovsky
2018-10-25 14:23         ` Joe Jin
2018-10-25 16:10           ` Boris Ostrovsky
2018-10-25 16:28             ` Joe Jin
2018-10-25 18:56               ` Joe Jin
2018-10-26  7:48                 ` Christoph Helwig
2018-10-26  8:54                   ` Dongli Zhang
2018-10-26 14:48                     ` Joe Jin [this message]
2018-10-26 14:40                   ` Joe Jin
2018-10-30  2:51                 ` Joe Jin
     [not found]                   ` <57e5593233c64dc0a36c7d4c750a1ed4@AMSPEX02CL03.citrite.net>
2018-10-30 14:12                     ` [Xen-devel] " Joe Jin
     [not found]                       ` <097f1f6f16f7415aa3a52a7c4f5e52dc@AMSPEX02CL03.citrite.net>
2018-10-30 14:48                         ` Joe Jin
2018-10-24 16:05   ` Joe Jin

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