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[Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API |
Date: |
Tue, 02 Mar 2010 17:31:09 +0100 |
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 |
Marcelo Tosatti wrote:
> On Tue, Mar 02, 2010 at 09:00:04AM +0100, Jan Kiszka wrote:
>> Marcelo Tosatti wrote:
>>> On Mon, Mar 01, 2010 at 07:10:30PM +0100, Jan Kiszka wrote:
>>>> This grand cleanup drops all reset and vmsave/load related
>>>> synchronization points in favor of four(!) generic hooks:
>>>>
>>>> - cpu_synchronize_all_states in qemu_savevm_state_complete
>>>> (initial sync from kernel before vmsave)
>>>> - cpu_synchronize_all_post_init in qemu_loadvm_state
>>>> (writeback after vmload)
>>>> - cpu_synchronize_all_post_init in main after machine init
>>>> - cpu_synchronize_all_post_reset in qemu_system_reset
>>>> (writeback after system reset)
>>>>
>>>> These writeback points + the existing one of VCPU exec after
>>>> cpu_synchronize_state map on three levels of writeback:
>>>>
>>>> - KVM_PUT_RUNTIME_STATE (during runtime, other VCPUs continue to run)
>>>> - KVM_PUT_RESET_STATE (on synchronous system reset, all VCPUs stopped)
>>>> - KVM_PUT_FULL_STATE (on init or vmload, all VCPUs stopped as well)
>>>>
>>>> This level is passed to the arch-specific VCPU state writing function
>>>> that will decide which concrete substates need to be written. That way,
>>>> no writer of load, save or reset functions that interact with in-kernel
>>>> KVM states will ever have to worry about synchronization again. That
>>>> also means that a lot of reasons for races, segfaults and deadlocks are
>>>> eliminated.
>>>>
>>>> cpu_synchronize_state remains untouched, just as Anthony suggested. We
>>>> continue to need it before reading or writing of VCPU states that are
>>>> also tracked by in-kernel KVM subsystems.
>>>>
>>>> Consequently, this patch removes many cpu_synchronize_state calls that
>>>> are now redundant, just like remaining explicit register syncs.
>>>>
>>>> Signed-off-by: Jan Kiszka <address@hidden>
>>> Jan,
>>>
>>> This patch breaks system reset of WinXP.32 install (more easily
>>> reproducible without iothread enabled).
>>>
>>> Screenshot attached.
>>>
>> Strange - no issues with qemu-kvm? Any special command line switch? /me
>> goes scrounging for some installation XP32 CD in the meantime...
>
> No issues with qemu-kvm. Could not spot anything obvious.
>
And, of course, my WinXP installation did not trigger any reset issue,
even in non-iothreaded mode. :(
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- [Qemu-devel] [PATCH 0/4] [uq/master] VCPU writeback rework and related bits, Jan Kiszka, 2010/03/01
- [Qemu-devel] [PATCH 3/4] KVM: x86: Restrict writeback of VCPU state, Jan Kiszka, 2010/03/01
- [Qemu-devel] [PATCH 2/4] KVM: Rework VCPU state writeback API, Jan Kiszka, 2010/03/01
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Marcelo Tosatti, 2010/03/01
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Jan Kiszka, 2010/03/02
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Marcelo Tosatti, 2010/03/02
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API,
Jan Kiszka <=
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Marcelo Tosatti, 2010/03/02
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Marcelo Tosatti, 2010/03/03
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Kevin O'Connor, 2010/03/04
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Marcelo Tosatti, 2010/03/04
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Kevin O'Connor, 2010/03/05
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Marcelo Tosatti, 2010/03/08
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Anthony Liguori, 2010/03/09
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Avi Kivity, 2010/03/11
- [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API, Marcelo Tosatti, 2010/03/11
[Qemu-devel] [PATCH 4/4] x86: Extend validity of bsp_to_cpu, Jan Kiszka, 2010/03/01