From: Julien Grall <julien@xen.org>
To: Jan Beulich <jbeulich@suse.com>, Penny Zheng <Penny.Zheng@arm.com>
Cc: Bertrand Marquis <Bertrand.Marquis@arm.com>,
Wei Chen <Wei.Chen@arm.com>, nd <nd@arm.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"sstabellini@kernel.org" <sstabellini@kernel.org>
Subject: Re: [PATCH 03/10] xen/arm: introduce PGC_reserved
Date: Thu, 20 May 2021 10:45:37 +0100 [thread overview]
Message-ID: <4b36ce2c-e60f-8974-fa5b-b8f2261e25ad@xen.org> (raw)
In-Reply-To: <b53c5ef5-ccab-a472-1edc-63082d89f09a@suse.com>
Hi Jan,
On 20/05/2021 10:27, Jan Beulich wrote:
> On 20.05.2021 10:59, Julien Grall wrote:
>> On 20/05/2021 09:40, Penny Zheng wrote:
>>> Oh, Second thought on this.
>>> And I think you are referring to balloon in/out here, hmm, also, like
>>
>> Yes I am referring to balloon in/out.
>>
>>> I replied there:
>>> "For issues on ballooning out or in, it is not supported here.
>>
>> So long you are not using the solution in prod then you are fine (see
>> below)... But then we should make clear this feature is a tech preview.
>>
>>> Domain on Static Allocation and 1:1 direct-map are all based on
>>> dom0-less right now, so no PV, grant table, event channel, etc, considered.
>>>
>>> Right now, it only supports device got passthrough into the guest."
>>
>> So we are not creating the hypervisor node in the DT for dom0less domU.
>> However, the hypercalls are still accessible by a domU if it really
>> wants to use them.
>>
>> Therefore, a guest can easily mess up with your static configuration and
>> predictability.
>>
>> IMHO, this is a must to solve before "static memory" can be used in
>> production.
>
> I'm having trouble seeing why it can't be addressed right away:
It can be solved right away. Dom0less domUs don't officially know they
are running on Xen (they could bruteforce it though), so I think it
would be fine to merge without it for a tech preview.
> Such
> guests can balloon in only after they've ballooned out some pages,
> and such balloon-in requests would be satisfied from the same static
> memory that is associated by the guest anyway.
This would require some bookeeping to know the page was used previously.
But nothing very challenging though.
Cheers,
--
Julien Grall
next prev parent reply other threads:[~2021-05-20 9:45 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-18 5:21 [PATCH 00/10] Domain on Static Allocation Penny Zheng
2021-05-18 5:21 ` [PATCH 01/10] xen/arm: introduce domain " Penny Zheng
2021-05-18 8:58 ` Julien Grall
2021-05-19 2:22 ` Penny Zheng
2021-05-19 18:27 ` Julien Grall
2021-05-20 6:07 ` Penny Zheng
2021-05-20 8:50 ` Julien Grall
2021-06-02 10:09 ` Penny Zheng
2021-06-03 9:09 ` Julien Grall
2021-06-03 21:32 ` Stefano Stabellini
2021-06-03 22:07 ` Julien Grall
2021-06-03 23:55 ` Stefano Stabellini
2021-06-04 4:00 ` Penny Zheng
2021-06-05 2:00 ` Stefano Stabellini
2021-06-07 18:09 ` Julien Grall
2021-06-09 9:56 ` Bertrand Marquis
2021-06-09 10:47 ` Julien Grall
2021-06-15 6:08 ` Penny Zheng
2021-06-17 11:22 ` Julien Grall
2021-05-18 5:21 ` [PATCH 02/10] xen/arm: handle static memory in dt_unreserved_regions Penny Zheng
2021-05-18 9:04 ` Julien Grall
2021-05-18 5:21 ` [PATCH 03/10] xen/arm: introduce PGC_reserved Penny Zheng
2021-05-18 9:45 ` Julien Grall
2021-05-19 3:16 ` Penny Zheng
2021-05-19 9:49 ` Jan Beulich
2021-05-19 19:49 ` Julien Grall
2021-05-20 7:05 ` Jan Beulich
2021-05-19 19:46 ` Julien Grall
2021-05-20 6:19 ` Penny Zheng
2021-05-20 8:40 ` Penny Zheng
2021-05-20 8:59 ` Julien Grall
2021-05-20 9:27 ` Jan Beulich
2021-05-20 9:45 ` Julien Grall [this message]
2021-05-18 5:21 ` [PATCH 04/10] xen/arm: static memory initialization Penny Zheng
2021-05-18 7:15 ` Jan Beulich
2021-05-18 9:51 ` Penny Zheng
2021-05-18 10:43 ` Jan Beulich
2021-05-20 9:04 ` Penny Zheng
2021-05-20 9:32 ` Jan Beulich
2021-05-18 10:00 ` Julien Grall
2021-05-18 10:01 ` Julien Grall
2021-05-19 5:02 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 05/10] xen/arm: introduce alloc_staticmem_pages Penny Zheng
2021-05-18 7:24 ` Jan Beulich
2021-05-18 9:30 ` Penny Zheng
2021-05-18 10:09 ` Julien Grall
2021-05-18 10:15 ` Julien Grall
2021-05-19 5:23 ` Penny Zheng
2021-05-24 10:10 ` Penny Zheng
2021-05-24 10:24 ` Julien Grall
2021-05-18 5:21 ` [PATCH 06/10] xen: replace order with nr_pfns in assign_pages for better compatibility Penny Zheng
2021-05-18 7:27 ` Jan Beulich
2021-05-18 9:11 ` Penny Zheng
2021-05-18 10:20 ` Julien Grall
2021-05-19 5:35 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 07/10] xen/arm: intruduce alloc_domstatic_pages Penny Zheng
2021-05-18 7:34 ` Jan Beulich
2021-05-18 8:57 ` Penny Zheng
2021-05-18 11:23 ` Jan Beulich
2021-05-21 6:41 ` Penny Zheng
2021-05-21 7:09 ` Jan Beulich
2021-06-03 2:44 ` Penny Zheng
2021-05-18 12:13 ` Julien Grall
2021-05-19 7:52 ` Penny Zheng
2021-05-19 20:01 ` Julien Grall
2021-05-18 10:30 ` Julien Grall
2021-05-19 6:03 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 08/10] xen/arm: introduce reserved_page_list Penny Zheng
2021-05-18 7:39 ` Jan Beulich
2021-05-18 8:38 ` Penny Zheng
2021-05-18 11:24 ` Jan Beulich
2021-05-19 6:46 ` Penny Zheng
2021-05-18 11:02 ` Julien Grall
2021-05-19 6:43 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 09/10] xen/arm: parse `xen,static-mem` info during domain construction Penny Zheng
2021-05-18 12:09 ` Julien Grall
2021-05-19 7:58 ` Penny Zheng
2021-05-18 5:21 ` [PATCH 10/10] xen/arm: introduce allocate_static_memory Penny Zheng
2021-05-18 12:05 ` Julien Grall
2021-05-19 7:27 ` Penny Zheng
2021-05-19 20:10 ` Julien Grall
2021-05-20 6:29 ` Penny Zheng
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