RE: [PATCH v2 04/10] Introduce the CPU address space destruction function

[Salil Mehta via <qemu-devel@nongnu.org>]

> From: David Hildenbrand <david@redhat.com>
> Sent: Friday, September 15, 2023 4:22 PM
> To: Philippe Mathieu-Daudé <philmd@linaro.org>; lixianglai
> <lixianglai@loongson.cn>; qemu-devel@nongnu.org; Salil Mehta
> <salil.mehta@huawei.com>
> Cc: Salil Mehta <salil.mehta@opnsrc.net>; Xiaojuan Yang
> <yangxiaojuan@loongson.cn>; Song Gao <gaosong@loongson.cn>; Michael S.
> Tsirkin <mst@redhat.com>; Igor Mammedov <imammedo@redhat.com>; Ani Sinha
> <anisinha@redhat.com>; Paolo Bonzini <pbonzini@redhat.com>; Richard
> Henderson <richard.henderson@linaro.org>; Eduardo Habkost
> <eduardo@habkost.net>; Marcel Apfelbaum <marcel.apfelbaum@gmail.com>;
> wangyanan (Y) <wangyanan55@huawei.com>; Daniel P. Berrangé
> <berrange@redhat.com>; Peter Xu <peterx@redhat.com>; Bibo Mao
> <maobibo@loongson.cn>
> Subject: Re: [PATCH v2 04/10] Introduce the CPU address space destruction
> function
> 
> On 15.09.23 16:19, Philippe Mathieu-Daudé wrote:
> > On 15/9/23 10:07, David Hildenbrand wrote:
> >
> >> The CPU implementation end up call qemu_init_vcpu() in their realize
> >> function; there should be something like qemu_destroy_vcpu() on the
> >> unrealize path that takes care of undoing any cpu_address_space_init().
> >>
> >> We seem to have cpu_common_unrealizefn()->cpu_exec_unrealizefn() but
> >> that doesn't take care of address spaces.
> >>
> >> Also, in qemu_init_vcpu() we do a cpus_accel->create_vcpu_thread(cpu).
> >> I'm, curious if we destroy that thread somehow.
> >
> > Implicitly in cpu_remove_sync().
> 
> Ah, indeed. there is the qemu_thread_join().

Correct. This one. 

For ARM, this was necessary because of the design approach
we have taken as a workaround to the ARM architecture limitations.
Th KVM needs to know everything at the VM initialization time.

Request to help review the patches:
https://lore.kernel.org/qemu-devel/20230926100436.28284-1-salil.mehta@huawei.com/T/#m523b37819c4811c7827333982004e07a1ef03879


Thanks
Salil.