diff mbox series

[RFC,12/52] hw/acpi: Replace MachineState.smp access with topology helpers

Message ID 20230213095035.158240-13-zhao1.liu@linux.intel.com
State New
Headers show
Series Introduce hybrid CPU topology | expand

Commit Message

Zhao Liu Feb. 13, 2023, 9:49 a.m. UTC 
From: Zhao Liu <zhao1.liu@intel.com>

At present, in QEMU only arm needs PPTT table to build cpu topology.

Before QEMU's arm supports hybrid architectures, it's enough to limit
the cpu topology of PPTT to smp type through the explicit smp interface
(machine_topo_get_smp_threads()).

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Ani Sinha <ani@anisinha.ca>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 hw/acpi/aml-build.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Zhao Liu Feb. 17, 2023, 3:14 a.m. UTC | #1 
On Thu, Feb 16, 2023 at 05:31:11PM +0800, wangyanan (Y) wrote:
> Date: Thu, 16 Feb 2023 17:31:11 +0800
> From: "wangyanan (Y)" <wangyanan55@huawei.com>
> Subject: Re: [RFC 12/52] hw/acpi: Replace MachineState.smp access with
>  topology helpers
> 
> Hi Zhao,
> 
> 在 2023/2/13 17:49, Zhao Liu 写道:
> > From: Zhao Liu <zhao1.liu@intel.com>
> > 
> > At present, in QEMU only arm needs PPTT table to build cpu topology.
> > 
> > Before QEMU's arm supports hybrid architectures, it's enough to limit
> > the cpu topology of PPTT to smp type through the explicit smp interface
> > (machine_topo_get_smp_threads()).
> > 
> > Cc: Michael S. Tsirkin <mst@redhat.com>
> > Cc: Igor Mammedov <imammedo@redhat.com>
> > Cc: Ani Sinha <ani@anisinha.ca>
> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> > ---
> >   hw/acpi/aml-build.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> > index ea331a20d131..693bd8833d10 100644
> > --- a/hw/acpi/aml-build.c
> > +++ b/hw/acpi/aml-build.c
> > @@ -2044,7 +2044,7 @@ void build_pptt(GArray *table_data, BIOSLinker *linker, MachineState *ms,
> >               cluster_offset = socket_offset;
> >           }
> > -        if (ms->smp.threads == 1) {
> > +        if (machine_topo_get_smp_threads(ms) == 1) {
> >               build_processor_hierarchy_node(table_data,
> >                   (1 << 1) | /* ACPI Processor ID valid */
> >                   (1 << 3),  /* Node is a Leaf */
> ACPI PPTT table is designed to also support the hybrid CPU topology
> case where nodes on the same CPU topology level can have different
> number of child nodes.
> 
> So to be general, the diff should be:
> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> index ea331a20d1..dfded95bbc 100644
> --- a/hw/acpi/aml-build.c
> +++ b/hw/acpi/aml-build.c
> @@ -2044,7 +2044,7 @@ void build_pptt(GArray *table_data, BIOSLinker
> *linker, MachineState *ms,
>              cluster_offset = socket_offset;
>          }
> 
> -        if (ms->smp.threads == 1) {
> +        if (machine_topo_get_threads_by_idx(n) == 1) {
>              build_processor_hierarchy_node(table_data,
>                  (1 << 1) | /* ACPI Processor ID valid */
>                  (1 << 3),  /* Node is a Leaf */

Nice! I'll replace that.

> 
> Actually I'm recently working on ARM hmp virtualization which relys on
> PPTT for topology representation, so we will also need PPTT to be general
> for hybrid case anyway.

Good to know that you are considering hybrid support for arm.
BTW, I explained the difference between arm and x86's hybrid in previous
email [1] [2], mainly about whether the cpm model is the same.

I tentatively think that this difference can be solved by arch-specific
coretype(). Do you have any comments on this? Thanks!

[1]: https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg03884.html
[2]: https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg03789.html

> 
> Thanks,
> Yanan
diff mbox series

Patch

diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index ea331a20d131..693bd8833d10 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -2044,7 +2044,7 @@  void build_pptt(GArray *table_data, BIOSLinker *linker, MachineState *ms,
             cluster_offset = socket_offset;
         }
 
-        if (ms->smp.threads == 1) {
+        if (machine_topo_get_smp_threads(ms) == 1) {
             build_processor_hierarchy_node(table_data,
                 (1 << 1) | /* ACPI Processor ID valid */
                 (1 << 3),  /* Node is a Leaf */