Re: [RFC PATCH v2 3/6] hw/arm/virt-acpi-build: Distinguish possible and present cpus

[wangyanan (Y)]

On 2021/4/27 21:18, Andrew Jones wrote:
> On Tue, Apr 13, 2021 at 04:07:42PM +0800, Yanan Wang wrote:
> > From: Ying Fang <fangying1@huawei.com>
> >
> > When building ACPI tables regarding CPUs we should always build
> > them for the number of possible CPUs, not the number of present
> > CPUs. We then ensure only the present CPUs are enabled in MADT.
> > Furthermore, it is also needed if we are going to support CPU
> > hotplug in the future.
> >
> > This patch is a rework based on Andrew Jones's contribution at
> > https://lists.gnu.org/archive/html/qemu-arm/2018-07/msg00076.html
> >
> > Signed-off-by: Ying Fang <fangying1@huawei.com>
> > Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> > ---
> >   hw/arm/virt-acpi-build.c | 14 ++++++++++----
> >   hw/arm/virt.c            |  3 +++
> >   2 files changed, 13 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> > index f5a2b2d4cb..2ad5dad1bf 100644
> > --- a/hw/arm/virt-acpi-build.c
> > +++ b/hw/arm/virt-acpi-build.c
> > @@ -61,13 +61,16 @@
> >   
> >   static void acpi_dsdt_add_cpus(Aml *scope, VirtMachineState *vms)
> >   {
> > -    MachineState *ms = MACHINE(vms);
> > +    CPUArchIdList *possible_cpus = MACHINE(vms)->possible_cpus;
> >       uint16_t i;
> >   
> > -    for (i = 0; i < ms->smp.cpus; i++) {
> > +    for (i = 0; i < possible_cpus->len; i++) {
> >           Aml *dev = aml_device("C%.03X", i);
> >           aml_append(dev, aml_name_decl("_HID", aml_string("ACPI0007")));
> >           aml_append(dev, aml_name_decl("_UID", aml_int(i)));
> > +        if (possible_cpus->cpus[i].cpu == NULL) {
> > +            aml_append(dev, aml_name_decl("_STA", aml_int(0)));
> > +        }
> >           aml_append(scope, dev);
> >       }
> >   }
> > @@ -479,6 +482,7 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
> > VirtMachineState *vms)
> >       const int *irqmap = vms->irqmap;
> >       AcpiMadtGenericDistributor *gicd;
> >       AcpiMadtGenericMsiFrame *gic_msi;
> > +    CPUArchIdList *possible_cpus = MACHINE(vms)->possible_cpus;
> >       int i;
> >   
> >       acpi_data_push(table_data, sizeof(AcpiMultipleApicTable));
> > @@ -489,7 +493,7 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
> > VirtMachineState *vms)
> >       gicd->base_address = cpu_to_le64(memmap[VIRT_GIC_DIST].base);
> >       gicd->version = vms->gic_version;
> >   
> > -    for (i = 0; i < MACHINE(vms)->smp.cpus; i++) {
> > +    for (i = 0; i < possible_cpus->len; i++) {
> >           AcpiMadtGenericCpuInterface *gicc = acpi_data_push(table_data,
> >                                                              sizeof(*gicc));
> >           ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(i));
> > @@ -504,7 +508,9 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
> > VirtMachineState *vms)
> >           gicc->cpu_interface_number = cpu_to_le32(i);
> >           gicc->arm_mpidr = cpu_to_le64(armcpu->mp_affinity);
> >           gicc->uid = cpu_to_le32(i);
> > -        gicc->flags = cpu_to_le32(ACPI_MADT_GICC_ENABLED);
> > +        if (possible_cpus->cpus[i].cpu != NULL) {
> > +            gicc->flags = cpu_to_le32(ACPI_MADT_GICC_ENABLED);
> > +        }
> >   
> >           if (arm_feature(&armcpu->env, ARM_FEATURE_PMU)) {
> >               gicc->performance_interrupt = cpu_to_le32(PPI(VIRTUAL_PMU_IRQ));
> > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > index f4ae60ded9..3e5d9b6f26 100644
> > --- a/hw/arm/virt.c
> > +++ b/hw/arm/virt.c
> > @@ -2063,6 +2063,9 @@ static void machvirt_init(MachineState *machine)
> >           }
> >   
> >           qdev_realize(DEVICE(cpuobj), NULL, &error_fatal);
> > +
> > +        /* Initialize cpu member here since cpu hotplug is not supported yet */
> > +        machine->possible_cpus->cpus[n].cpu = cpuobj;
> Can drop the 'machine->' as possible_cpus is already set to the pointer.
Right, I will drop it.

Thanks,
Yanan
> >           object_unref(cpuobj);
> >       }
> >       fdt_add_timer_nodes(vms);
> > --
> > 2.19.1
> Thanks,
> drew
>
>
> .