RE: [PATCH RFC V2 22/37] hw/acpi: Make _MAT method optional

[Salil Mehta]

Hi Gavin,

> From: Gavin Shan <gshan@redhat.com>
> Sent: Friday, September 29, 2023 12:50 AM
> To: Salil Mehta <salil.mehta@huawei.com>; qemu-devel@nongnu.org; 
> qemu-arm@nongnu.org
> Cc: maz@kernel.org; jean-philippe@linaro.org; Jonathan Cameron
> <jonathan.cameron@huawei.com>; 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; will@kernel.org; ardb@kernel.org;
> oliver.upton@linux.dev; pbonzini@redhat.com; mst@redhat.com;
> rafael@kernel.org; borntraeger@linux.ibm.com; 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
> Subject: Re: [PATCH RFC V2 22/37] hw/acpi: Make _MAT method optional
> 
> On 9/26/23 20:04, Salil Mehta wrote:
> > From: Jean-Philippe Brucker <jean-philippe@linaro.org>
> >
> > The GICC interface on arm64 vCPUs is statically defined in the MADT, and
> > doesn't require a _MAT entry. Although the GICC is indicated as present
> > by the MADT entry, it can only be used from vCPU sysregs, which aren't
> > accessible until hot-add.
> >
> > Co-developed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Co-developed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> > Signed-off-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> > Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
> > ---
> >   hw/acpi/cpu.c | 12 +++++++-----
> >   1 file changed, 7 insertions(+), 5 deletions(-)
> >
> 
> With following nits addressed:
> 
> Reviewed-by: Gavin Shan <gshan@redhat.com>

Thanks.


> 
> > diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
> > index e1299696d3..217db99538 100644
> > --- a/hw/acpi/cpu.c
> > +++ b/hw/acpi/cpu.c
> > @@ -715,11 +715,13 @@ void build_cpus_aml(Aml *table, MachineState
> *machine, CPUHotplugFeatures opts,
> >               aml_append(dev, method);
> >
> >               /* build _MAT object */
> > -            assert(adevc && adevc->madt_cpu);
> > -            adevc->madt_cpu(i, arch_ids, madt_buf,
> > -                            true); /* set enabled flag */
> > -            aml_append(dev, aml_name_decl("_MAT",
> > -                aml_buffer(madt_buf->len, (uint8_t *)madt_buf->data)));
> > +            if (adevc && adevc->madt_cpu) {
> > +                assert(adevc && adevc->madt_cpu);
> > +                adevc->madt_cpu(i, arch_ids, madt_buf,
> > +                                true); /* set enabled flag */
> > +                aml_append(dev, aml_name_decl("_MAT",
> > +                    aml_buffer(madt_buf->len, (uint8_t *)madt_buf->data)));
> > +            }
> >               g_array_free(madt_buf, true);
> >
> >               if (CPU(arch_ids->cpus[i].cpu) != first_cpu) {
> 
> May be worthy to have comment to mention _MAT isn't needed on aarch64.
> 
>                 /* Build _MAT object, which isn't needed by aarch64 */

This file is not an architecture specific file so not a good idea
to mention above.


Thanks
Salil.