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[Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API
From: |
Marcelo Tosatti |
Subject: |
[Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API |
Date: |
Mon, 1 Mar 2010 21:14:15 -0300 |
User-agent: |
Mutt/1.5.20 (2009-08-17) |
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.
uqmaster-failure.png
Description: PNG image
- [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 <=
- [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, 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, 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