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Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken de
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state |
Date: |
Tue, 23 Oct 2012 11:07:11 +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 2012-10-23 07:52, liu ping fan wrote:
> On Mon, Oct 22, 2012 at 6:40 PM, Avi Kivity <address@hidden> wrote:
>> On 10/22/2012 11:23 AM, Liu Ping Fan wrote:
>>> The broken device state is caused by releasing local lock before acquiring
>>> big lock. To fix this issue, we have two choice:
>>> 1.use busy flag to protect the state
>>> The drawback is that we will introduce independent busy flag for each
>>> independent device's logic unit.
>>> 2.reload the device's state
>>> The drawback is if the call chain is too deep, the action to reload will
>>> touch each layer. Also the reloading means to recaculate the
>>> intermediate
>>> result based on device's regs.
>>>
>>> This patch adopt the solution 1 to fix the issue.
>>
>> Doesn't the nested mmio patch detect this?
>>
> It will only record and fix the issue on one thread. But guest can
> touch the emulated device on muti-threads.
Sorry, what does that mean? A second VCPU accessing the device will
simply be ignored when it races with another VCPU? Specifically
+ if (s->busy) {
+ return;
and
+ uint64_t ret = 0;
+
+ if (s->busy) {
+ return ret;
is worrying me.
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
[Qemu-devel] [patch v4 03/16] hotplug: introduce qdev_unplug_complete() to remove device from views, Liu Ping Fan, 2012/10/22
[Qemu-devel] [patch v4 01/16] atomic: introduce atomic operations, Liu Ping Fan, 2012/10/22
[Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Liu Ping Fan, 2012/10/22
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Avi Kivity, 2012/10/22
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, liu ping fan, 2012/10/23
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Avi Kivity, 2012/10/23
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state,
Jan Kiszka <=
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, liu ping fan, 2012/10/23
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Avi Kivity, 2012/10/23
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, liu ping fan, 2012/10/24
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Avi Kivity, 2012/10/25
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Peter Maydell, 2012/10/25
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Avi Kivity, 2012/10/25
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, liu ping fan, 2012/10/25
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, liu ping fan, 2012/10/25
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, Jan Kiszka, 2012/10/26
- Re: [Qemu-devel] [patch v4 13/16] e1000: add busy flag to anti broken device state, liu ping fan, 2012/10/29