Re: [PATCH V13 6/8] physmem: Add helper function to destroy CPU AddressSpace

[Salil Mehta]

On 06/07/2024 14:37, Igor Mammedov wrote:
> On Fri, 7 Jun 2024 12:56:47 +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>
> > Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> > Reviewed-by: Gavin Shan <gshan@redhat.com>
> > Tested-by: Xianglai Li <lixianglai@loongson.cn>
> > Tested-by: Miguel Luis <miguel.luis@oracle.com>
> > Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> > Tested-by: Zhao Liu <zhao1.liu@intel.com>
>
> Acked-by: Igor Mammedov <imammedo@redhat.com>
Thanks, Salil.
> > ---
> >   include/exec/cpu-common.h |  8 ++++++++
> >   include/hw/core/cpu.h     |  1 +
> >   system/physmem.c          | 29 +++++++++++++++++++++++++++++
> >   3 files changed, 38 insertions(+)
> >
> > diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
> > index 815342d043..240ee04369 100644
> > --- a/include/exec/cpu-common.h
> > +++ b/include/exec/cpu-common.h
> > @@ -129,6 +129,14 @@ 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 bb398e8237..60b160d0b4 100644
> > --- a/include/hw/core/cpu.h
> > +++ b/include/hw/core/cpu.h
> > @@ -486,6 +486,7 @@ struct CPUState {
> >       QSIMPLEQ_HEAD(, qemu_work_item) work_list;
> >   
> >       struct CPUAddressSpace *cpu_ases;
> > +    int cpu_ases_count;
> >       int num_ases;
> >       AddressSpace *as;
> >       MemoryRegion *memory;
> > diff --git a/system/physmem.c b/system/physmem.c
> > index 342b7a8fd4..146f17826a 100644
> > --- a/system/physmem.c
> > +++ b/system/physmem.c
> > @@ -763,6 +763,7 @@ 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];
> > @@ -776,6 +777,34 @@ void cpu_address_space_init(CPUState *cpu, int asidx,
> >       }
> >   }
> >   
> > +void cpu_address_space_destroy(CPUState *cpu, int asidx)
> > +{
> > +    CPUAddressSpace *cpuas;
> > +
> > +    assert(cpu->cpu_ases);
> > +    assert(asidx >= 0 && asidx < cpu->num_ases);
> > +    /* KVM cannot currently support multiple address spaces. */
> > +    assert(asidx == 0 || !kvm_enabled());
> > +
> > +    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 (asidx == 0) {
> > +        /* reset the convenience alias for address space 0 */
> > +        cpu->as = NULL;
> > +    }
> > +
> > +    if (--cpu->cpu_ases_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 */