diff mbox series

[v2,6/7] x86/Kconfig: Introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE

Message ID 20210209133854.17399-7-osalvador@suse.de (mailing list archive)
State New, archived
Headers show
Series Allocate memmap from hotadded memory (per device) | expand

Commit Message

Oscar Salvador Feb. 9, 2021, 1:38 p.m. UTC
Enable x86_64 platform to use the MHP_MEMMAP_ON_MEMORY feature.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
 arch/x86/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

Comments

David Hildenbrand Feb. 25, 2021, 6:29 p.m. UTC | #1
On 09.02.21 14:38, Oscar Salvador wrote:
> Enable x86_64 platform to use the MHP_MEMMAP_ON_MEMORY feature.
> 
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> ---
>   arch/x86/Kconfig | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 72663de8b04c..81046b7adb10 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2440,6 +2440,10 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
>   	def_bool y
>   	depends on MEMORY_HOTPLUG
>   
> +config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
> +	def_bool y
> +	depends on X86_64 && MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP_ENABLE

It depends on SPARSEMEM_VMEMMAP, no?

I think we could have

SPARSEMEM_VMEMMAP_ENABLE=y
and
SPARSEMEM_VMEMMAP=n

on manually tuned configs.
Oscar Salvador Feb. 26, 2021, 12:04 p.m. UTC | #2
On Thu, Feb 25, 2021 at 07:29:07PM +0100, David Hildenbrand wrote:
> On 09.02.21 14:38, Oscar Salvador wrote:
> > Enable x86_64 platform to use the MHP_MEMMAP_ON_MEMORY feature.
> > 
> > Signed-off-by: Oscar Salvador <osalvador@suse.de>
> > ---
> >   arch/x86/Kconfig | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 72663de8b04c..81046b7adb10 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -2440,6 +2440,10 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
> >   	def_bool y
> >   	depends on MEMORY_HOTPLUG
> > +config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
> > +	def_bool y
> > +	depends on X86_64 && MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP_ENABLE
> 
> It depends on SPARSEMEM_VMEMMAP, no?
> 
> I think we could have
> 
> SPARSEMEM_VMEMMAP_ENABLE=y
> and
> SPARSEMEM_VMEMMAP=n
> 
> on manually tuned configs.

I do not think this can happen:

from mm/Kconfig:

config SPARSEMEM_VMEMMAP_ENABLE
        bool

config SPARSEMEM_VMEMMAP
        bool "Sparse Memory virtual memmap"
        depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
        default y
        help
          SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
          pfn_to_page and page_to_pfn operations.  This is the most
          efficient option when sufficient kernel resources are available

and from arch/x86/Kconfig:

config ARCH_SPARSEMEM_ENABLE
        def_bool y
        depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
        select SPARSEMEM_STATIC if X86_32
        select SPARSEMEM_VMEMMAP_ENABLE if X86_64


So, if I read this correctly, for SPARSEMEM_VMEMMAP to be true,
SPARSEMEM_VMEMMAP_ENABLE needs to be true as well.

Am I missing something?
David Hildenbrand March 1, 2021, 8:45 a.m. UTC | #3
On 26.02.21 13:04, Oscar Salvador wrote:
> On Thu, Feb 25, 2021 at 07:29:07PM +0100, David Hildenbrand wrote:
>> On 09.02.21 14:38, Oscar Salvador wrote:
>>> Enable x86_64 platform to use the MHP_MEMMAP_ON_MEMORY feature.
>>>
>>> Signed-off-by: Oscar Salvador <osalvador@suse.de>
>>> ---
>>>    arch/x86/Kconfig | 4 ++++
>>>    1 file changed, 4 insertions(+)
>>>
>>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>>> index 72663de8b04c..81046b7adb10 100644
>>> --- a/arch/x86/Kconfig
>>> +++ b/arch/x86/Kconfig
>>> @@ -2440,6 +2440,10 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
>>>    	def_bool y
>>>    	depends on MEMORY_HOTPLUG
>>> +config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
>>> +	def_bool y
>>> +	depends on X86_64 && MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP_ENABLE
>>
>> It depends on SPARSEMEM_VMEMMAP, no?
>>
>> I think we could have
>>
>> SPARSEMEM_VMEMMAP_ENABLE=y
>> and
>> SPARSEMEM_VMEMMAP=n
>>
>> on manually tuned configs.
> 
> I do not think this can happen:
> 
> from mm/Kconfig:
> 
> config SPARSEMEM_VMEMMAP_ENABLE
>          bool
> 
> config SPARSEMEM_VMEMMAP
>          bool "Sparse Memory virtual memmap"
>          depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
>          default y
>          help
>            SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
>            pfn_to_page and page_to_pfn operations.  This is the most
>            efficient option when sufficient kernel resources are available
> 
> and from arch/x86/Kconfig:
> 
> config ARCH_SPARSEMEM_ENABLE
>          def_bool y
>          depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
>          select SPARSEMEM_STATIC if X86_32
>          select SPARSEMEM_VMEMMAP_ENABLE if X86_64
> 
> 
> So, if I read this correctly, for SPARSEMEM_VMEMMAP to be true,
> SPARSEMEM_VMEMMAP_ENABLE needs to be true as well.
> 
> Am I missing something?

Take your config and set
	X86_5LEVEL=n
(because it enforces SPARSEMEM_VMEMMAP)
and
	SPARSEMEM_VMEMMAP=n

When compiling, you'll end up with a config like
	CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y
	# CONFIG_SPARSEMEM_VMEMMAP is not set

Yet, with your patch you would get

ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE=y

And it would not get fenced off in the code, right?


I think you either have to check (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) 
in addition in your code, or enforce it differently. Like


config MHP_MEMMAP_ON_MEMORY
	depends on SPARSEMEM_VMEMMAP && ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
	bool


Then you can simplify the arch Kconfig settings, removing the sparesemem 
dependency there.
Oscar Salvador March 1, 2021, 10:07 a.m. UTC | #4
On Mon, Mar 01, 2021 at 09:45:07AM +0100, David Hildenbrand wrote:
> Take your config and set
> 	X86_5LEVEL=n
> (because it enforces SPARSEMEM_VMEMMAP)
> and
> 	SPARSEMEM_VMEMMAP=n
> 
> When compiling, you'll end up with a config like
> 	CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y
> 	# CONFIG_SPARSEMEM_VMEMMAP is not set

I see

> 
> Yet, with your patch you would get
> 
> ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE=y
> 
> And it would not get fenced off in the code, right?
> 
> 
> I think you either have to check (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) in
> addition in your code, or enforce it differently. Like
> 
> 
> config MHP_MEMMAP_ON_MEMORY
> 	depends on SPARSEMEM_VMEMMAP && ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
> 	bool
> 
> 
> Then you can simplify the arch Kconfig settings, removing the sparesemem
> dependency there.

Yes, will do it this way.

Thanks!
diff mbox series

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 72663de8b04c..81046b7adb10 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2440,6 +2440,10 @@  config ARCH_ENABLE_MEMORY_HOTREMOVE
 	def_bool y
 	depends on MEMORY_HOTPLUG
 
+config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
+	def_bool y
+	depends on X86_64 && MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP_ENABLE
+
 config USE_PERCPU_NUMA_NODE_ID
 	def_bool y
 	depends on NUMA