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From: George Dunlap <george.dunlap@citrix.com>
To: "Yu, Zhang" <yu.c.zhang@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
	"jun.nakajima@intel.com" <jun.nakajima@intel.com>,
	Andrew Cooper <Andrew.Cooper3@citrix.com>,
	"Tim (Xen.org)" <tim@xen.org>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	Paul Durrant <Paul.Durrant@citrix.com>,
	"Lv, Zhiyuan" <zhiyuan.lv@intel.com>,
	Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH v2 3/3] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server
Date: Wed, 20 Apr 2016 15:50:08 +0100	[thread overview]
Message-ID: <CAFLBxZaZreeOvT9OwEWuvkA7ihgqh_giodWXQF5LM4BOqm8Y3w@mail.gmail.com> (raw)
In-Reply-To: <57161D9E.6030509@linux.intel.com>

On Tue, Apr 19, 2016 at 12:59 PM, Yu, Zhang <yu.c.zhang@linux.intel.com> wrote:
>>> So what about the VM suspend case you mentioned above? Will that trigger
>>> the unmapping of ioreq server? Could the device model also take the role
>>> to change the p2m type back in such case?
>>
>>
>> Yes. The device model has to be told by the toolstack that the VM is
>> suspending, otherwise it can't disable the ioreq server which puts the
>> shared ioreq pages back into the guest p2m. If that's not done then the
>> pages will be leaked.
>>
>>>
>>> It would be much simpler if hypervisor side does not need to provide
>>> the p2m resetting logic, and we can support live migration at the same
>>> time then. :)
>>>
>>
>> That really should not be hypervisor's job.
>>
>>    Paul
>>
>
> Oh. So let's just remove the p2m type recalculation code from this
> patch, no need to call p2m_change_entry_type_global, and no need to
> worry about the log dirty part.
>
> George, do you think this acceptable?

Sorry, just to make sure I understand your intentions:

1. The ioreq servers will be responsible for changing all the
p2m_ioreq_server types back to p2m_ram_rw before detaching
2. Xen will refuse to set logdirty mode if there are any attached ioreq servers

The one problem with #1 is what to do if the ioreq server is buggy /
killed, and forgets / is unable to clean up its ioreq_server entries?

There's a certain symmetry with the idea of having the ioreq server
responsible both for mapping and unmapping; and it would be nice to
have this stuff work for shadow mode as well.  But the automatic type
change seems like a more robust option.  (Still open to persuasion on
this.)

On another note: the hard freeze is long past the already-extended
deadline, so I was assuming this was 4.8 material at this point.

 -George

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  reply	other threads:[~2016-04-20 14:50 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-31 10:53 [PATCH v2 0/3] x86/ioreq server: introduce HVMMEM_ioreq_server mem type Yu Zhang
2016-03-31 10:53 ` [PATCH v2 1/3] x86/ioreq server: Add new functions to get/set memory types Yu Zhang
2016-04-05 13:57   ` George Dunlap
2016-04-05 14:08     ` George Dunlap
2016-04-08 13:25   ` Andrew Cooper
2016-03-31 10:53 ` [PATCH v2 2/3] x86/ioreq server: Rename p2m_mmio_write_dm to p2m_ioreq_server Yu Zhang
2016-04-05 14:38   ` George Dunlap
2016-04-08 13:26   ` Andrew Cooper
2016-04-08 21:48   ` Jan Beulich
2016-04-18  8:41     ` Paul Durrant
2016-04-18  9:10       ` George Dunlap
2016-04-18  9:14         ` Wei Liu
2016-04-18  9:45           ` Paul Durrant
2016-04-18 16:40       ` Jan Beulich
2016-04-18 16:45         ` Paul Durrant
2016-04-18 16:47           ` Jan Beulich
2016-04-18 16:58             ` Paul Durrant
2016-04-19 11:02               ` Yu, Zhang
2016-04-19 11:15                 ` Paul Durrant
2016-04-19 11:38                   ` Yu, Zhang
2016-04-19 11:50                     ` Paul Durrant
2016-04-19 16:51                     ` Jan Beulich
2016-04-20 14:59                       ` Wei Liu
2016-04-20 15:02                 ` George Dunlap
2016-04-20 16:30                   ` George Dunlap
2016-04-20 16:52                     ` Jan Beulich
2016-04-20 16:58                       ` Paul Durrant
2016-04-20 17:06                         ` George Dunlap
2016-04-20 17:09                           ` Paul Durrant
2016-04-21 12:24                           ` Yu, Zhang
2016-04-21 13:31                             ` Paul Durrant
2016-04-21 13:48                               ` Yu, Zhang
2016-04-21 13:56                                 ` Paul Durrant
2016-04-21 14:09                                   ` George Dunlap
2016-04-20 17:08                       ` George Dunlap
2016-04-21 12:04                       ` Yu, Zhang
2016-03-31 10:53 ` [PATCH v2 3/3] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server Yu Zhang
     [not found]   ` <20160404082556.GC28633@deinos.phlegethon.org>
2016-04-05  6:01     ` Yu, Zhang
2016-04-06 17:13   ` George Dunlap
2016-04-07  7:01     ` Yu, Zhang
     [not found]       ` <CAFLBxZbLp2zWzCzQTaJNWbanQSmTJ57ZyTh0qaD-+YUn8o8pyQ@mail.gmail.com>
2016-04-08 10:39         ` George Dunlap
     [not found]         ` <5707839F.9060803@linux.intel.com>
2016-04-08 11:01           ` George Dunlap
2016-04-11 11:15             ` Yu, Zhang
2016-04-14 10:45               ` Yu, Zhang
2016-04-18 15:57                 ` Paul Durrant
2016-04-19  9:11                   ` Yu, Zhang
2016-04-19  9:21                     ` Paul Durrant
2016-04-19  9:44                       ` Yu, Zhang
2016-04-19 10:05                         ` Paul Durrant
2016-04-19 11:17                           ` Yu, Zhang
2016-04-19 11:47                             ` Paul Durrant
2016-04-19 11:59                               ` Yu, Zhang
2016-04-20 14:50                                 ` George Dunlap [this message]
2016-04-20 14:57                                   ` Paul Durrant
2016-04-20 15:37                                     ` George Dunlap
2016-04-20 16:30                                       ` Paul Durrant
2016-04-20 16:58                                         ` George Dunlap
2016-04-21 13:28                                         ` Yu, Zhang
2016-04-21 13:21                                   ` Yu, Zhang
2016-04-22 11:27                                     ` Wei Liu
2016-04-22 11:30                                       ` George Dunlap
2016-04-19  4:37                 ` Tian, Kevin
2016-04-19  9:21                   ` Yu, Zhang
2016-04-08 13:33   ` Andrew Cooper
2016-04-11 11:14     ` Yu, Zhang
2016-04-11 12:20       ` Andrew Cooper
2016-04-11 16:25         ` Jan Beulich
2016-04-08 22:28   ` Jan Beulich
2016-04-11 11:14     ` Yu, Zhang
2016-04-11 16:31       ` Jan Beulich
2016-04-12  9:37         ` Yu, Zhang
2016-04-12 15:08           ` Jan Beulich
2016-04-14  9:56             ` Yu, Zhang
2016-04-19  4:50               ` Tian, Kevin
2016-04-19  8:46                 ` Paul Durrant
2016-04-19  9:27                   ` Yu, Zhang
2016-04-19  9:40                     ` Paul Durrant
2016-04-19  9:49                       ` Yu, Zhang
2016-04-19 10:01                         ` Paul Durrant
2016-04-19  9:54                           ` Yu, Zhang
2016-04-19  9:15                 ` Yu, Zhang
2016-04-19  9:23                   ` Paul Durrant

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