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Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycl
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem |
Date: |
Mon, 27 Aug 2012 20:17:41 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-08-27 20:09, Avi Kivity wrote:
> On 08/27/2012 10:14 AM, Jan Kiszka wrote:
>>>
>>> Deregistration is fine, the problem is destruction.
>>>
>>
>> It isn't as you access memory region states that can change after
>> deregistration. Devices can remove memory regions from the mapping,
>> alter and then reinsert them. The last to steps must not happen while
>> anyone is still using a reference to that region.
>>
>
> Why not? If the guest is accessing an mmio region while reconfiguring
> it in a way that changes its meaning, either the previous or the next
> meaning is valid.
If the memory region owner sets the content to zero or even releases it
(nothing states a memory region can only live inside a device
structure), we will crash. Restricting how a memory region can be
created and handled after it was once registered somewhere is an
unnatural interface, waiting to cause subtle bugs.
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
- [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, (continued)
- [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Liu Ping Fan, 2012/08/24
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Paolo Bonzini, 2012/08/24
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, liu ping fan, 2012/08/25
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Paolo Bonzini, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, liu ping fan, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Avi Kivity, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Avi Kivity, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem,
Jan Kiszka <=
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Avi Kivity, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Avi Kivity, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Avi Kivity, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/27
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Avi Kivity, 2012/08/29
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/29
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Avi Kivity, 2012/08/29
- Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem, Jan Kiszka, 2012/08/29