linux-kernel - Re: [HMM-CDM 5/5] mm/hmm: simplify kconfig and enable HMM and DEVICE

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Message-ID: <20170615114611.34e8f2a7@firefly.ozlabs.ibm.com>
Date:   Thu, 15 Jun 2017 11:46:11 +1000
From:   Balbir Singh <bsingharora@...il.com>
To:     Jérôme Glisse <jglisse@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        John Hubbard <jhubbard@...dia.com>,
        David Nellans <dnellans@...dia.com>,
        Balbir Singh <balbirs@....ibm.com>,
        Aneesh Kumar <aneesh.kumar@...ux.vnet.ibm.com>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [HMM-CDM 5/5] mm/hmm: simplify kconfig and enable HMM and
 DEVICE_PUBLIC for ppc64

On Wed, 14 Jun 2017 16:11:44 -0400
Jérôme Glisse <jglisse@...hat.com> wrote:

> This just simplify kconfig and allow HMM and DEVICE_PUBLIC to be
> selected for ppc64 once ZONE_DEVICE is allowed on ppc64 (different
> patchset).
> 
> Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
> Signed-off-by: John Hubbard <jhubbard@...dia.com>
> Cc: Balbir Singh <balbirs@....ibm.com>
> Cc: Aneesh Kumar <aneesh.kumar@...ux.vnet.ibm.com>
> Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> ---
>  include/linux/hmm.h |  4 ++--
>  mm/Kconfig          | 27 ++++++---------------------
>  mm/hmm.c            |  4 ++--
>  3 files changed, 10 insertions(+), 25 deletions(-)
> 
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index f6713b2..720d18c 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -327,7 +327,7 @@ int hmm_vma_fault(struct vm_area_struct *vma,
>  #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
>  
>  
> -#if IS_ENABLED(CONFIG_HMM_DEVMEM)
> +#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) || IS_ENABLED(CONFIG_DEVICE_PUBLIC)
>  struct hmm_devmem;
>  
>  struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma,
> @@ -456,7 +456,7 @@ struct hmm_device {
>   */
>  struct hmm_device *hmm_device_new(void *drvdata);
>  void hmm_device_put(struct hmm_device *hmm_device);
> -#endif /* IS_ENABLED(CONFIG_HMM_DEVMEM) */
> +#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
>  
>  
>  /* Below are for HMM internal use only! Not to be used by device driver! */
> diff --git a/mm/Kconfig b/mm/Kconfig
> index ad082b9..7de939a 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -265,7 +265,7 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION
>  config ARCH_HAS_HMM
>  	bool
>  	default y
> -	depends on X86_64
> +	depends on X86_64 || PPC64

Ideally we want to make this (PPC64 && PPC_BOOK3S)

>  	depends on ZONE_DEVICE
>  	depends on MMU && 64BIT
>  	depends on MEMORY_HOTPLUG
> @@ -277,7 +277,7 @@ config HMM
>  
>  config HMM_MIRROR
>  	bool "HMM mirror CPU page table into a device page table"
> -	depends on ARCH_HAS_HMM
> +	depends on ARCH_HAS_HMM && X86_64

We would need HMM_MIRROR for the generation of hardware that does
not have CDM

>  	select MMU_NOTIFIER
>  	select HMM
>  	help
> @@ -287,15 +287,6 @@ config HMM_MIRROR
>  	  page tables (at PAGE_SIZE granularity), and must be able to recover from
>  	  the resulting potential page faults.
>  
> -config HMM_DEVMEM
> -	bool "HMM device memory helpers (to leverage ZONE_DEVICE)"
> -	depends on ARCH_HAS_HMM
> -	select HMM
> -	help
> -	  HMM devmem is a set of helper routines to leverage the ZONE_DEVICE
> -	  feature. This is just to avoid having device drivers to replicating a lot
> -	  of boiler plate code.  See Documentation/vm/hmm.txt.
> -
>  config PHYS_ADDR_T_64BIT
>  	def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
>  
> @@ -720,11 +711,8 @@ config ZONE_DEVICE
>  
>  config DEVICE_PRIVATE
>  	bool "Unaddressable device memory (GPU memory, ...)"
> -	depends on X86_64
> -	depends on ZONE_DEVICE
> -	depends on MEMORY_HOTPLUG
> -	depends on MEMORY_HOTREMOVE
> -	depends on SPARSEMEM_VMEMMAP
> +	depends on ARCH_HAS_HMM && X86_64

Same as above

> +	select HMM
>  
>  	help
>  	  Allows creation of struct pages to represent unaddressable device
> @@ -733,11 +721,8 @@ config DEVICE_PRIVATE
>  
>  config DEVICE_PUBLIC
>  	bool "Unaddressable device memory (GPU memory, ...)"

The unaddressable is a typo from above.

> -	depends on X86_64
> -	depends on ZONE_DEVICE
> -	depends on MEMORY_HOTPLUG
> -	depends on MEMORY_HOTREMOVE
> -	depends on SPARSEMEM_VMEMMAP
> +	depends on ARCH_HAS_HMM
> +	select HMM
>  

Balbir Singh.