RE: [PATCH 07/22] exec/cpu: Introduce the CPU address space destruction function

[Salil Mehta]

Hi Phillipe,
This patch has been taken as it is from ARM's RFC and the common patch-set 
mentioned below.
So SOBs are all wrong everywhere.


Original RFC posted in the year 2020.
[1] 
https://lore.kernel.org/qemu-devel/20200613213629.21984-23-salil.mehta@huawei.com/

Recently posted RFC V2
[2] 
https://lore.kernel.org/qemu-devel/20230926100436.28284-1-salil.mehta@huawei.com/T/#m5f5ae40b091d69d01012880d7500d96874a9d39c

Recent common patch-set for Virtual CPU Hotplug
[3] 
https://lore.kernel.org/qemu-devel/20230930001933.2660-9-salil.mehta@huawei.com/

[4] 
https://lore.kernel.org/qemu-devel/20230930001933.2660-10-salil.mehta@huawei.com/

Beside my original patch-set had bug which you have inherited in this patch-set.
 
Thanks
Salil


> From: qemu-arm-bounces+salil.mehta=huawei.com@nongnu.org <qemu-arm-
> bounces+salil.mehta=huawei.com@nongnu.org> On Behalf Of Philippe Mathieu-
> Daudé
> Sent: Monday, September 18, 2023 5:03 PM
> To: qemu-devel@nongnu.org
> Cc: Laurent Vivier <laurent@vivier.eu>; Paolo Bonzini
> <pbonzini@redhat.com>; Max Filippov <jcmvbkbc@gmail.com>; David Hildenbrand
> <david@redhat.com>; Peter Xu <peterx@redhat.com>; Anton Johansson
> <anjo@rev.ng>; Peter Maydell <peter.maydell@linaro.org>;
> kvm@vger.kernel.org; Marek Vasut <marex@denx.de>; David Gibson
> <david@gibson.dropbear.id.au>; Brian Cain <bcain@quicinc.com>; Yoshinori
> Sato <ysato@users.sourceforge.jp>; Edgar E . Iglesias
> <edgar.iglesias@gmail.com>; Claudio Fontana <cfontana@suse.de>; Daniel
> Henrique Barboza <dbarboza@ventanamicro.com>; Artyom Tarasenko
> <atar4qemu@gmail.com>; Marcelo Tosatti <mtosatti@redhat.com>; qemu-
> ppc@nongnu.org; Liu Zhiwei <zhiwei_liu@linux.alibaba.com>; Aurelien Jarno
> <aurelien@aurel32.net>; Ilya Leoshkevich <iii@linux.ibm.com>; Daniel
> Henrique Barboza <danielhb413@gmail.com>; Bastian Koppelmann
> <kbastian@mail.uni-paderborn.de>; Cédric Le Goater <clg@kaod.org>; Alistair
> Francis <alistair.francis@wdc.com>; Alessandro Di Federico <ale@rev.ng>;
> Song Gao <gaosong@loongson.cn>; Marcel Apfelbaum
> <marcel.apfelbaum@gmail.com>; Chris Wulff <crwulff@gmail.com>; Michael S.
> Tsirkin <mst@redhat.com>; Alistair Francis <alistair@alistair23.me>;
> Fabiano Rosas <farosas@suse.de>; qemu-s390x@nongnu.org; wangyanan (Y)
> <wangyanan55@huawei.com>; Luc Michel <luc@lmichel.fr>; Weiwei Li
> <liweiwei@iscas.ac.cn>; Bin Meng <bin.meng@windriver.com>; Stafford Horne
> <shorne@gmail.com>; Xiaojuan Yang <yangxiaojuan@loongson.cn>; Daniel P .
> Berrange <berrange@redhat.com>; Thomas Huth <thuth@redhat.com>; Philippe
> Mathieu-Daudé <philmd@linaro.org>; qemu-arm@nongnu.org; Jiaxun Yang
> <jiaxun.yang@flygoat.com>; Richard Henderson
> <richard.henderson@linaro.org>; Aleksandar Rikalo
> <aleksandar.rikalo@syrmia.com>; Bernhard Beschow <shentey@gmail.com>; Mark
> Cave-Ayland <mark.cave-ayland@ilande.co.uk>; qemu-riscv@nongnu.org; Alex
> Bennée <alex.bennee@linaro.org>; Nicholas Piggin <npiggin@gmail.com>; Greg
> Kurz <groug@kaod.org>; Michael Rolnik <mrolnik@gmail.com>; Eduardo Habkost
> <eduardo@habkost.net>; Markus Armbruster <armbru@redhat.com>; Palmer
> Dabbelt <palmer@dabbelt.com>; xianglai li <lixianglai@loongson.cn>; Salil
> Mehta <salil.mehta@opnsrc.net>; Igor Mammedov <imammedo@redhat.com>; Ani
> Sinha <anisinha@redhat.com>; Bibo Mao <maobibo@loongson.cn>
> Subject: [PATCH 07/22] exec/cpu: Introduce the CPU address space
> destruction function
> 
> From: xianglai li <lixianglai@loongson.cn>
> 
> Introduce new function to destroy CPU address space resources
> for cpu hot-(un)plug.
> 
> Co-authored-by: "Salil Mehta" <salil.mehta@opnsrc.net>
> Cc: "Salil Mehta" <salil.mehta@opnsrc.net>
> Cc: Xiaojuan Yang <yangxiaojuan@loongson.cn>
> Cc: Song Gao <gaosong@loongson.cn>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Ani Sinha <anisinha@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Richard Henderson <richard.henderson@linaro.org>
> Cc: Eduardo Habkost <eduardo@habkost.net>
> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> Cc: "Philippe Mathieu-Daudé" <philmd@linaro.org>
> Cc: Yanan Wang <wangyanan55@huawei.com>
> Cc: "Daniel P. Berrangé" <berrange@redhat.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Bibo Mao <maobibo@loongson.cn>
> Signed-off-by: xianglai li <lixianglai@loongson.cn>
> Message-ID:
> <3a4fc2a3df4b767c3c296a7da3bc15ca9c251316.1694433326.git.lixianglai@loongso
> n.cn>
> ---
>  include/exec/cpu-common.h |  8 ++++++++
>  include/hw/core/cpu.h     |  1 +
>  softmmu/physmem.c         | 24 ++++++++++++++++++++++++
>  3 files changed, 33 insertions(+)
> 
> diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
> index 41788c0bdd..eb56a228a2 100644
> --- a/include/exec/cpu-common.h
> +++ b/include/exec/cpu-common.h
> @@ -120,6 +120,14 @@ size_t qemu_ram_pagesize_largest(void);
>   */
>  void cpu_address_space_init(CPUState *cpu, int asidx,
>                              const char *prefix, MemoryRegion *mr);
> +/**
> + * cpu_address_space_destroy:
> + * @cpu: CPU for which address space needs to be destroyed
> + * @asidx: integer index of this address space
> + *
> + * Note that with KVM only one address space is supported.
> + */
> +void cpu_address_space_destroy(CPUState *cpu, int asidx);
> 
>  void cpu_physical_memory_rw(hwaddr addr, void *buf,
>                              hwaddr len, bool is_write);
> diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
> index 92a4234439..c90cf3a162 100644
> --- a/include/hw/core/cpu.h
> +++ b/include/hw/core/cpu.h
> @@ -366,6 +366,7 @@ struct CPUState {
>      QSIMPLEQ_HEAD(, qemu_work_item) work_list;
> 
>      CPUAddressSpace *cpu_ases;
> +    int cpu_ases_ref_count;
>      int num_ases;
>      AddressSpace *as;
>      MemoryRegion *memory;
> diff --git a/softmmu/physmem.c b/softmmu/physmem.c
> index 18277ddd67..c75e3e8042 100644
> --- a/softmmu/physmem.c
> +++ b/softmmu/physmem.c
> @@ -761,6 +761,7 @@ void cpu_address_space_init(CPUState *cpu, int asidx,
> 
>      if (!cpu->cpu_ases) {
>          cpu->cpu_ases = g_new0(CPUAddressSpace, cpu->num_ases);
> +        cpu->cpu_ases_ref_count = cpu->num_ases;
>      }
> 
>      newas = &cpu->cpu_ases[asidx];
> @@ -774,6 +775,29 @@ void cpu_address_space_init(CPUState *cpu, int asidx,
>      }
>  }
> 
> +void cpu_address_space_destroy(CPUState *cpu, int asidx)
> +{
> +    CPUAddressSpace *cpuas;
> +
> +    assert(asidx < cpu->num_ases);
> +    assert(asidx == 0 || !kvm_enabled());
> +    assert(cpu->cpu_ases);
> +
> +    cpuas = &cpu->cpu_ases[asidx];
> +    if (tcg_enabled()) {
> +        memory_listener_unregister(&cpuas->tcg_as_listener);
> +    }
> +
> +    address_space_destroy(cpuas->as);
> +
> +    cpu->cpu_ases_ref_count--;
> +    if (cpu->cpu_ases_ref_count == 0) {
> +        g_free(cpu->cpu_ases);
> +        cpu->cpu_ases = NULL;
> +    }
> +
> +}
> +
>  AddressSpace *cpu_get_address_space(CPUState *cpu, int asidx)
>  {
>      /* Return the AddressSpace corresponding to the specified index */
> --
> 2.41.0
> 
>