From: Avi Kivity <avi@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Liu Ping Fan <pingfank@linux.vnet.ibm.com>,
liu ping fan <qemulist@gmail.com>,
Anthony Liguori <anthony@codemonkey.ws>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem
Date: Mon, 27 Aug 2012 11:20:39 -0700 [thread overview]
Message-ID: <503BBA77.4090006@redhat.com> (raw)
In-Reply-To: <503BB9C5.3030605@siemens.com>
On 08/27/2012 11:17 AM, Jan Kiszka wrote:
> 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.
Using an Object * allows the simple case to be really simple (object ==
device) and the hard cases to be doable.
What would you suggest as a better interface?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2012-08-27 18:20 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-24 9:49 [Qemu-devel] [PATCH 0/10] rework on hot unplug Liu Ping Fan
2012-08-24 9:49 ` [Qemu-devel] [PATCH 01/10] qom: add, remove of link property need to ref, unref its target Liu Ping Fan
2012-08-24 14:52 ` Paolo Bonzini
2012-08-24 9:49 ` [Qemu-devel] [PATCH 02/10] qdev: change iterator callback seq Liu Ping Fan
2012-08-24 9:49 ` [Qemu-devel] [PATCH 03/10] qom: export object_property_is_child, object_property_is_link Liu Ping Fan
2012-08-24 14:51 ` Paolo Bonzini
2012-08-25 7:43 ` liu ping fan
2012-08-25 8:04 ` Blue Swirl
2012-08-24 9:49 ` [Qemu-devel] [PATCH 04/10] qdev: introduce new interface to remove composite sub-tree Liu Ping Fan
2012-08-24 9:49 ` [Qemu-devel] [PATCH 05/10] qdev: finalize of qbus, qdev will not the right place to free children Liu Ping Fan
2012-08-24 14:50 ` Paolo Bonzini
2012-08-24 9:49 ` [Qemu-devel] [PATCH 06/10] qom: expose object_property_del_child Liu Ping Fan
2012-08-24 14:44 ` Paolo Bonzini
2012-08-24 9:49 ` [Qemu-devel] [PATCH 07/10] unplug: using new intf qdev_delete_subtree in acpi_piix_eject_slot Liu Ping Fan
2012-08-24 10:24 ` Paolo Bonzini
2012-08-25 7:05 ` liu ping fan
2012-08-24 9:49 ` [Qemu-devel] [PATCH 08/10] qdev: rename qdev_unplug to qdev_unplug_req Liu Ping Fan
2012-08-24 14:48 ` Paolo Bonzini
2012-08-24 9:49 ` [Qemu-devel] [PATCH 09/10] mon: release dev's ref hold by qdev_get_peripheral Liu Ping Fan
2012-08-24 9:49 ` [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life cycle problem Liu Ping Fan
2012-08-24 14:42 ` Paolo Bonzini
2012-08-25 7:42 ` liu ping fan
2012-08-27 7:01 ` Paolo Bonzini
2012-08-27 7:47 ` Jan Kiszka
2012-08-27 8:17 ` liu ping fan
2012-08-27 8:27 ` Jan Kiszka
2012-08-27 17:09 ` Avi Kivity
2012-08-27 17:14 ` Jan Kiszka
2012-08-27 18:09 ` Avi Kivity
2012-08-27 18:17 ` Jan Kiszka
2012-08-27 18:20 ` Avi Kivity [this message]
2012-08-27 18:39 ` Jan Kiszka
2012-08-27 18:52 ` Avi Kivity
2012-08-27 19:38 ` Jan Kiszka
2012-08-27 20:53 ` Avi Kivity
2012-08-28 1:01 ` Jan Kiszka
2012-08-29 17:13 ` Avi Kivity
2012-08-29 17:21 ` Jan Kiszka
2012-08-29 17:27 ` Avi Kivity
2012-08-29 17:41 ` Jan Kiszka
2012-09-03 9:09 ` Avi Kivity
2012-08-28 3:09 ` liu ping fan
2012-08-28 3:38 ` liu ping fan
2012-08-28 9:42 ` Jan Kiszka
2012-08-28 10:05 ` Paolo Bonzini
2012-08-29 17:23 ` Avi Kivity
2012-08-29 17:30 ` Jan Kiszka
2012-08-29 17:40 ` Avi Kivity
2012-08-29 17:49 ` Jan Kiszka
2012-09-01 8:31 ` Avi Kivity
2012-09-01 8:57 ` Jan Kiszka
2012-09-01 9:30 ` Avi Kivity
2012-08-30 5:54 ` liu ping fan
2012-08-30 7:08 ` Jan Kiszka
2012-08-30 7:47 ` liu ping fan
2012-09-01 8:46 ` Avi Kivity
2012-09-03 7:44 ` liu ping fan
2012-09-03 8:52 ` Avi Kivity
2012-09-03 10:06 ` liu ping fan
2012-09-03 10:16 ` Avi Kivity
2012-09-04 2:33 ` liu ping fan
2012-09-04 2:34 ` liu ping fan
2012-09-05 8:19 ` liu ping fan
2012-09-05 9:52 ` Avi Kivity
2012-09-05 10:36 ` Jan Kiszka
2012-09-05 10:53 ` Avi Kivity
2012-09-05 11:11 ` Jan Kiszka
2012-09-05 11:25 ` Avi Kivity
2012-09-05 12:02 ` Jan Kiszka
2012-09-05 12:17 ` Avi Kivity
2012-08-27 13:19 ` Anthony Liguori
2012-08-27 15:02 ` Jan Kiszka
2012-08-27 15:14 ` Anthony Liguori
2012-08-27 15:26 ` Jan Kiszka
2012-08-27 16:24 ` Anthony Liguori
2012-08-27 16:59 ` Jan Kiszka
2012-08-27 18:35 ` Avi Kivity
2012-08-27 19:17 ` Anthony Liguori
2012-08-27 19:22 ` Jan Kiszka
2012-08-27 20:58 ` Avi Kivity
2012-08-27 21:34 ` Paolo Bonzini
2012-08-27 18:27 ` Avi Kivity
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