[RFT,v5,0/5] Unify CPU topology across ARM & RISC-V

The cpu-map DT entry in ARM can describe the CPU topology in much better
way compared to other existing approaches. RISC-V can easily adopt this
binding to represent its own CPU topology. Thus, both cpu-map DT
binding and topology parsing code can be moved to a common location so
that RISC-V or any other architecture can leverage that.

The relevant discussion regarding unifying cpu topology can be found in
[1].

arch_topology seems to be a perfect place to move the common code. I
have not introduced any significant functional changes in the moved code.
The only downside in this approach is that the capacity code will be
executed for RISC-V as well. But, it will exit immediately after not
able to find the appropriate DT node. If the overhead is considered too
much, we can always compile out capacity related functions under a
different config for the architectures that do not support them.

There was an opportunity to unify topology data structure for ARM32 done
by patch 3/4. But, I refrained from making any other changes as I am not
very well versed with original intention for some functions that
are present in arch_topology.c. I hope this patch series can be served
as a baseline for such changes in the future.

The patches have been tested for RISC-V and compile tested for ARM64,
ARM32 & x86.

The socket change[2] is also now part of this series.

[1] https://lkml.org/lkml/2018/11/6/19
[2] https://lkml.org/lkml/2018/11/7/918

QEMU changes for RISC-V topology are available at

https://github.com/atishp04/qemu/tree/riscv_topology_dt

HiFive Unleashed DT with topology node is available here.
https://github.com/atishp04/opensbi/tree/HiFive_unleashed_topology

It can be verified with OpenSBI with following additional compile time
option.

FW_PAYLOAD_FDT="unleashed_topology.dtb"

Changes from v4-v5
1. Removed the arch_topology.h header inclusion from topology.c and arch_topology.c
file. Added it in linux/topology.h.
2. core_id is set to -1 upon reset. Otherwise, ARM topology store function does not
work.

Changes from v3->v4
1. Get rid of ARM32 specific information in topology structure.
2. Remove redundant functions from ARM32 and use common code instead. 

Changes from v2->v3
1. Cover letter update with experiment DT for topology changes.
2. Added the patch for [2].

Changes from v1->v2
1. ARM32 can now use the common code as well.

Atish Patra (4):
dt-binding: cpu-topology: Move cpu-map to a common binding.
cpu-topology: Move cpu topology code to common code.
arm: Use common cpu_topology structure and functions.
RISC-V: Parse cpu topology during boot.

Sudeep Holla (1):
Documentation: DT: arm: add support for sockets defining package
boundaries

.../topology.txt => cpu/cpu-topology.txt}     | 134 ++++++--
arch/arm/include/asm/topology.h               |  20 --
arch/arm/kernel/topology.c                    |  60 +---
arch/arm64/include/asm/topology.h             |  23 --
arch/arm64/kernel/topology.c                  | 303 +-----------------
arch/riscv/Kconfig                            |   1 +
arch/riscv/kernel/smpboot.c                   |   3 +
drivers/base/arch_topology.c                  | 298 +++++++++++++++++
include/linux/arch_topology.h                 |  26 ++
include/linux/topology.h                      |   1 +
10 files changed, 444 insertions(+), 425 deletions(-)
rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (66%)

--
2.21.0

On Thu, May 23, 2019 at 05:06:50PM -0700, Atish Patra wrote:
> Both RISC-V & ARM64 are using cpu-map device tree to describe
> their cpu topology. It's better to move the relevant code to
> a common place instead of duplicate code.
> 
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
> ---
>  arch/arm64/include/asm/topology.h |  23 ---
>  arch/arm64/kernel/topology.c      | 303 +-----------------------------
>  drivers/base/arch_topology.c      | 296 +++++++++++++++++++++++++++++
>  include/linux/arch_topology.h     |  28 +++
>  include/linux/topology.h          |   1 +
>  5 files changed, 329 insertions(+), 322 deletions(-)

What, now _I_ have to maintain drivers/base/arch_topology.c?  That's
nice for everyone else, but not me :(

Ugh.

Anyway, what are you wanting to happen to this series?  I think we need
some ARM people to sign off on it before I can take the whole thing,
right?

thanks,

greg k-h

On Fri, May 24, 2019 at 10:13:33AM +0200, Greg Kroah-Hartman wrote:
> On Thu, May 23, 2019 at 05:06:50PM -0700, Atish Patra wrote:
> > Both RISC-V & ARM64 are using cpu-map device tree to describe
> > their cpu topology. It's better to move the relevant code to
> > a common place instead of duplicate code.
> > 
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
> > ---
> >  arch/arm64/include/asm/topology.h |  23 ---
> >  arch/arm64/kernel/topology.c      | 303 +-----------------------------
> >  drivers/base/arch_topology.c      | 296 +++++++++++++++++++++++++++++
> >  include/linux/arch_topology.h     |  28 +++
> >  include/linux/topology.h          |   1 +
> >  5 files changed, 329 insertions(+), 322 deletions(-)
>
> What, now _I_ have to maintain drivers/base/arch_topology.c?  That's
> nice for everyone else, but not me :(
>
> Ugh.
>
> Anyway, what are you wanting to happen to this series?  I think we need
> some ARM people to sign off on it before I can take the whole thing,
> right?
>

Greg, I am ready to take ownership. Juri the original author of this file
agreed and I have been reviewing this file since Juri first wrote it.
I am happy to submit a patch assuming maintainership for this file, was
just waiting to hear from you when I asked explicitly you and Juri in
last version of the patch when Will wanted someone from ARM to be reviewer
of this file at-least. I am happy to take over as reviewer or maintainer
which ever you prefer.

Sorry if I was not so clear in my earlier mail.

--
Regards,
Sudeep

On Fri, May 24, 2019 at 09:57:40AM +0100, Sudeep Holla wrote:
> On Fri, May 24, 2019 at 10:13:33AM +0200, Greg Kroah-Hartman wrote:
> > On Thu, May 23, 2019 at 05:06:50PM -0700, Atish Patra wrote:
> > > Both RISC-V & ARM64 are using cpu-map device tree to describe
> > > their cpu topology. It's better to move the relevant code to
> > > a common place instead of duplicate code.
> > > 
> > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
> > > ---
> > >  arch/arm64/include/asm/topology.h |  23 ---
> > >  arch/arm64/kernel/topology.c      | 303 +-----------------------------
> > >  drivers/base/arch_topology.c      | 296 +++++++++++++++++++++++++++++
> > >  include/linux/arch_topology.h     |  28 +++
> > >  include/linux/topology.h          |   1 +
> > >  5 files changed, 329 insertions(+), 322 deletions(-)
> >
> > What, now _I_ have to maintain drivers/base/arch_topology.c?  That's
> > nice for everyone else, but not me :(
> >
> > Ugh.
> >
> > Anyway, what are you wanting to happen to this series?  I think we need
> > some ARM people to sign off on it before I can take the whole thing,
> > right?
> >
> 
> Greg, I am ready to take ownership. Juri the original author of this file
> agreed and I have been reviewing this file since Juri first wrote it.
> I am happy to submit a patch assuming maintainership for this file, was
> just waiting to hear from you when I asked explicitly you and Juri in
> last version of the patch when Will wanted someone from ARM to be reviewer
> of this file at-least. I am happy to take over as reviewer or maintainer
> which ever you prefer.

Yes, please just include this update to MAINTAINERS as part of the series.
I'll ack it.

Will

On Thu, May 23, 2019 at 05:06:50PM -0700, Atish Patra wrote:
> Both RISC-V & ARM64 are using cpu-map device tree to describe
> their cpu topology. It's better to move the relevant code to
> a common place instead of duplicate code.
>

I couldn't test this on any ARM64 server platforms, tested on Juno
and other embedded platforms.

Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
> ---
>  arch/arm64/include/asm/topology.h |  23 ---
>  arch/arm64/kernel/topology.c      | 303 +-----------------------------
>  drivers/base/arch_topology.c      | 296 +++++++++++++++++++++++++++++
>  include/linux/arch_topology.h     |  28 +++
>  include/linux/topology.h          |   1 +
>  5 files changed, 329 insertions(+), 322 deletions(-)
>

[...]

> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index 0825c4a856e3..6b95c91e7d67 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
>

[...]

> -static int __init parse_cluster(struct device_node *cluster, int depth)
> -{
> -	char name[10];
> -	bool leaf = true;
> -	bool has_cores = false;
> -	struct device_node *c;
> -	static int package_id __initdata;
> -	int core_id = 0;

[Ultra minor nit]: you seem to have reordered the above declaration when
you moved, just noticed as it showed up when comparing.

> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 1739d7e1952a..20a960131bee 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c

[...]

> +
> +static int __init parse_cluster(struct device_node *cluster, int depth)
> +{
> +	char name[10];
> +	bool leaf = true;
> +	bool has_cores = false;
> +	int core_id = 0;
> +	static int package_id __initdata;
> +	struct device_node *c;
> +	int i, ret;
> +

[...]

> +#if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
> +void update_siblings_masks(unsigned int cpu);
> +#endif
> +void remove_cpu_topology(unsigned int cpuid);
> +

Another thing(not a block and we can do it once this is merged) is to
remove these #ifdefs

--
Regards,
Sudeep

On Thu, May 23, 2019 at 05:06:51PM -0700, Atish Patra wrote:
> Currently, ARM32 and ARM64 uses different data structures to represent
> their cpu topologies. Since, we are moving the ARM64 topology to common
> code to be used by other architectures, we can reuse that for ARM32 as
> well.
> 
> Take this opprtunity to remove the redundant functions from ARM32 and
> reuse the common code instead.
> 

Tested-by: Sudeep Holla <sudeep.holla@arm.com> (on TC2)
Reviewed-by : Sudeep Holla <sudeep.holla@arm.com>

--
Regards,
Sudeep

On 5/29/19 3:48 AM, Sudeep Holla wrote:
> On Thu, May 23, 2019 at 05:06:50PM -0700, Atish Patra wrote:
>> Both RISC-V & ARM64 are using cpu-map device tree to describe
>> their cpu topology. It's better to move the relevant code to
>> a common place instead of duplicate code.
>>
> 
> I couldn't test this on any ARM64 server platforms, tested on Juno
> and other embedded platforms.
> 

Jeff had tested earlier patch series on ARM64 server platform.
Since then, the series has changed. Even though, I don't expect it break 
ARM64, if it can be verified again that would be great.

@Jeff: Can you give it a shot if you have some time ?

> Tested-by: Sudeep Holla <sudeep.holla@arm.com>
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
> 

Thanks!

>> Signed-off-by: Atish Patra <atish.patra@wdc.com>
>> Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
>> ---
>>   arch/arm64/include/asm/topology.h |  23 ---
>>   arch/arm64/kernel/topology.c      | 303 +-----------------------------
>>   drivers/base/arch_topology.c      | 296 +++++++++++++++++++++++++++++
>>   include/linux/arch_topology.h     |  28 +++
>>   include/linux/topology.h          |   1 +
>>   5 files changed, 329 insertions(+), 322 deletions(-)
>>
> 
> [...]
> 
>> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
>> index 0825c4a856e3..6b95c91e7d67 100644
>> --- a/arch/arm64/kernel/topology.c
>> +++ b/arch/arm64/kernel/topology.c
>>
> 
> [...]
> 
>> -static int __init parse_cluster(struct device_node *cluster, int depth)
>> -{
>> -	char name[10];
>> -	bool leaf = true;
>> -	bool has_cores = false;
>> -	struct device_node *c;
>> -	static int package_id __initdata;
>> -	int core_id = 0;
> 
> [Ultra minor nit]: you seem to have reordered the above declaration when
> you moved, just noticed as it showed up when comparing.
> 

Arrgh. Sorry!

I think I was trying to fix a checkpatch or something and forgot to 
revert. I will update it.

>> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
>> index 1739d7e1952a..20a960131bee 100644
>> --- a/drivers/base/arch_topology.c
>> +++ b/drivers/base/arch_topology.c
> 
> [...]
> 
>> +
>> +static int __init parse_cluster(struct device_node *cluster, int depth)
>> +{
>> +	char name[10];
>> +	bool leaf = true;
>> +	bool has_cores = false;
>> +	int core_id = 0;
>> +	static int package_id __initdata;
>> +	struct device_node *c;
>> +	int i, ret;
>> +
> 
> [...]
> 
>> +#if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
>> +void update_siblings_masks(unsigned int cpu);
>> +#endif
>> +void remove_cpu_topology(unsigned int cpuid);
>> +
> 
> Another thing(not a block and we can do it once this is merged) is to
> remove these #ifdefs
> 

This #ifdef is removed in patch 4.

But we should remove the other ones around init_cpu_topology, 
parse_dt_topology and friends in a follow up patch once this is merged.

> --
> Regards,
> Sudeep
>