Re: [PATCH 5/8] x86: acpi: let the firmware handle pending "CPU remove" events in SMM

[Igor Mammedov]

On Sun, 6 Dec 2020 22:20:27 -0800
Ankur Arora <ankur.a.arora@oracle.com> wrote:

> On 2020-12-04 9:09 a.m., Igor Mammedov wrote:
> > if firmware and QEMU negotiated CPU hotunplug support, generate
> > _EJ0 method so that it will mark CPU for removal by firmware and
> > pass control to it by triggering SMI.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> >   include/hw/acpi/cpu.h |  1 +
> >   hw/acpi/cpu.c         | 15 +++++++++++++--
> >   hw/i386/acpi-build.c  |  1 +
> >   3 files changed, 15 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/hw/acpi/cpu.h b/include/hw/acpi/cpu.h
> > index d71edde456..999caaf510 100644
> > --- a/include/hw/acpi/cpu.h
> > +++ b/include/hw/acpi/cpu.h
> > @@ -51,6 +51,7 @@ void cpu_hotplug_hw_init(MemoryRegion *as, Object *owner,
> >   typedef struct CPUHotplugFeatures {
> >       bool acpi_1_compatible;
> >       bool has_legacy_cphp;
> > +    bool fw_unplugs_cpu;
> >       const char *smi_path;
> >   } CPUHotplugFeatures;
> >   
> > diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
> > index 811218f673..bded2a837f 100644
> > --- a/hw/acpi/cpu.c
> > +++ b/hw/acpi/cpu.c
> > @@ -341,6 +341,7 @@ const VMStateDescription vmstate_cpu_hotplug = {
> >   #define CPU_INSERT_EVENT  "CINS"
> >   #define CPU_REMOVE_EVENT  "CRMV"
> >   #define CPU_EJECT_EVENT   "CEJ0"
> > +#define CPU_FW_EJECT_EVENT "CEJF"
> >   
> >   void build_cpus_aml(Aml *table, MachineState *machine, CPUHotplugFeatures 
> > opts,
> >                       hwaddr io_base,
> > @@ -393,7 +394,10 @@ void build_cpus_aml(Aml *table, MachineState *machine, 
> > CPUHotplugFeatures opts,
> >           aml_append(field, aml_named_field(CPU_REMOVE_EVENT, 1));  
> 
>    Bit 2: Device remove event, used to distinguish device for which
>          no device eject request to OSPM was issued. Firmware must
>          ignore this bit.
> 
> >           /* initiates device eject, write only */
> >           aml_append(field, aml_named_field(CPU_EJECT_EVENT, 1));  
> 
>    Bit 3: reserved and should be ignored by OSPM
> 
> > -        aml_append(field, aml_reserved_field(4));
> > +        aml_append(field, aml_reserved_field(1));
> > +        /* tell firmware to do device eject, write only */
> > +        aml_append(field, aml_named_field(CPU_FW_EJECT_EVENT, 1));
> > +        aml_append(field, aml_reserved_field(2));  
> 
> Shouldn't this be instead:
> 
> > -        aml_append(field, aml_reserved_field(4));
> > +        /* tell firmware to do device eject, write only */
> > +        aml_append(field, aml_named_field(CPU_FW_EJECT_EVENT, 1));
> > +        aml_append(field, aml_reserved_field(3));  
> 

yes, it should be this way,
I'll fix in v2

>    Bit 4: if set to 1, OSPM requests firmware to perform device eject.
>    Bit 5-7: reserved and should be ignored by OSPM
> 
> Otherwise AFAICS CPU_FW_EJECT_EVENT would correspond to bit 5.
> 
> 
> Ankur
> 
> >           aml_append(field, aml_named_field(CPU_COMMAND, 8));
> >           aml_append(cpu_ctrl_dev, field);
> >   
> > @@ -428,6 +432,7 @@ void build_cpus_aml(Aml *table, MachineState *machine, 
> > CPUHotplugFeatures opts,
> >           Aml *ins_evt = aml_name("%s.%s", cphp_res_path, CPU_INSERT_EVENT);
> >           Aml *rm_evt = aml_name("%s.%s", cphp_res_path, CPU_REMOVE_EVENT);
> >           Aml *ej_evt = aml_name("%s.%s", cphp_res_path, CPU_EJECT_EVENT);
> > +        Aml *fw_ej_evt = aml_name("%s.%s", cphp_res_path, 
> > CPU_FW_EJECT_EVENT);
> >   
> >           aml_append(cpus_dev, aml_name_decl("_HID", 
> > aml_string("ACPI0010")));
> >           aml_append(cpus_dev, aml_name_decl("_CID", 
> > aml_eisaid("PNP0A05")));
> > @@ -470,7 +475,13 @@ void build_cpus_aml(Aml *table, MachineState *machine, 
> > CPUHotplugFeatures opts,
> >   
> >               aml_append(method, aml_acquire(ctrl_lock, 0xFFFF));
> >               aml_append(method, aml_store(idx, cpu_selector));
> > -            aml_append(method, aml_store(one, ej_evt));
> > +            if (opts.fw_unplugs_cpu) {
> > +                aml_append(method, aml_store(one, fw_ej_evt));
> > +                aml_append(method, aml_store(aml_int(OVMF_CPUHP_SMI_CMD),
> > +                           aml_name("%s", opts.smi_path)));
> > +            } else {
> > +                aml_append(method, aml_store(one, ej_evt));
> > +            }
> >               aml_append(method, aml_release(ctrl_lock));
> >           }
> >           aml_append(cpus_dev, method);
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index 9036e5594c..475e76f514 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -1586,6 +1586,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >           CPUHotplugFeatures opts = {
> >               .acpi_1_compatible = true, .has_legacy_cphp = true,
> >               .smi_path = pm->smi_on_cpuhp ? "\\_SB.PCI0.SMI0.SMIC" : NULL,
> > +            .fw_unplugs_cpu = pm->smi_on_cpu_unplug,
> >           };
> >           build_cpus_aml(dsdt, machine, opts, pm->cpu_hp_io_base,
> >                          "\\_SB.PCI0", "\\_GPE._E02");
> >   
>