RE: [PATCH V2 08/10] physmem: Add helper function to destroy CPU AddressSpace

[Salil Mehta]

Hi Jonathan,

> From: Jonathan Cameron <jonathan.cameron@huawei.com>
> Sent: Monday, October 2, 2023 5:20 PM
> To: Salil Mehta <salil.mehta@huawei.com>
> Cc: qemu-devel@nongnu.org; qemu-arm@nongnu.org; maz@kernel.org; jean-
> philippe@linaro.org; lpieralisi@kernel.org; peter.maydell@linaro.org;
> richard.henderson@linaro.org; imammedo@redhat.com; andrew.jones@linux.dev;
> david@redhat.com; philmd@linaro.org; eric.auger@redhat.com;
> oliver.upton@linux.dev; pbonzini@redhat.com; mst@redhat.com;
> will@kernel.org; gshan@redhat.com; rafael@kernel.org;
> alex.bennee@linaro.org; linux@armlinux.org.uk;
> darren@os.amperecomputing.com; ilkka@os.amperecomputing.com;
> vishnu@os.amperecomputing.com; karl.heubaum@oracle.com;
> miguel.luis@oracle.com; salil.mehta@opnsrc.net; zhukeqian
> <zhukeqian1@huawei.com>; wangxiongfeng (C) <wangxiongfeng2@huawei.com>;
> wangyanan (Y) <wangyanan55@huawei.com>; jiakernel2@gmail.com;
> maobibo@loongson.cn; lixianglai@loongson.cn; Linuxarm <linuxarm@huawei.com>
> Subject: Re: [PATCH V2 08/10] physmem: Add helper function to destroy CPU
> AddressSpace
> 
> On Sat, 30 Sep 2023 01:19:31 +0100
> Salil Mehta <salil.mehta@huawei.com> wrote:
> 
> > Virtual CPU Hot-unplug leads to unrealization of a CPU object. This also
> > involves destruction of the CPU AddressSpace. Add common function to help
> > destroy the CPU AddressSpace.
> >
> > Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
> 
> I'm not that familiar with this bit of the code, so no tag, but
> as far as I can tell from a fairly superficial look, this is good.

Ok no problem. Thanks.

Salil.


> >  include/exec/cpu-common.h |  8 ++++++++
> >  include/hw/core/cpu.h     |  1 +
> >  softmmu/physmem.c         | 25 +++++++++++++++++++++++++
> >  3 files changed, 34 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 648b5b3586..65d2ae4581 100644
> > --- a/include/hw/core/cpu.h
> > +++ b/include/hw/core/cpu.h
> > @@ -355,6 +355,7 @@ struct CPUState {
> >      QSIMPLEQ_HEAD(, qemu_work_item) work_list;
> >
> >      CPUAddressSpace *cpu_ases;
> > +    int cpu_ases_count;
> >      int num_ases;
> >      AddressSpace *as;
> >      MemoryRegion *memory;
> > diff --git a/softmmu/physmem.c b/softmmu/physmem.c
> > index 4f6ca653b3..4dfa0ca66f 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_count = cpu->num_ases;
> >      }
> >
> >      newas = &cpu->cpu_ases[asidx];
> > @@ -774,6 +775,30 @@ 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);
> > +    g_free_rcu(cpuas->as, rcu);
> > +
> > +    if (cpu->cpu_ases_count == 1) {
> > +        g_free(cpu->cpu_ases);
> > +        cpu->cpu_ases = NULL;
> > +    }
> > +
> > +    cpu->cpu_ases_count--;
> > +}
> > +
> >  AddressSpace *cpu_get_address_space(CPUState *cpu, int asidx)
> >  {
> >      /* Return the AddressSpace corresponding to the specified index */