[v3,2/2] powerpc/mm/hugetlb: Add support for 1G huge pages

Message ID 1494995292-4443-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com
State Not Applicable
Headers show

Commit Message

Aneesh Kumar K.V May 17, 2017, 4:28 a.m.
POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch
enables the usage of 1G page size for hugetlbfs. This also update the helper
such we can do 1G page allocation at runtime.

We still don't enable 1G page size on DD1 version. This is to avoid doing
workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add
radix__tlb_flush_pte_p9_dd1()

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++
 arch/powerpc/mm/hugetlbpage.c                |  7 +++++--
 arch/powerpc/platforms/Kconfig.cputype       |  1 +
 3 files changed, 16 insertions(+), 2 deletions(-)

Comments

Michael Ellerman May 18, 2017, 5:21 a.m. | #1
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:

> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch
> enables the usage of 1G page size for hugetlbfs. This also update the helper
> such we can do 1G page allocation at runtime.
>
> We still don't enable 1G page size on DD1 version. This is to avoid doing
> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add
> radix__tlb_flush_pte_p9_dd1()
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++
>  arch/powerpc/mm/hugetlbpage.c                |  7 +++++--
>  arch/powerpc/platforms/Kconfig.cputype       |  1 +
>  3 files changed, 16 insertions(+), 2 deletions(-)

I think this patch is OK, but it's very confusing because it doesn't
mention that it's only talking about *generic* gigantic page support.

We have existing support for gigantic pages on powerpc, on several
platforms. This patch appears to break that, but I think doesn't in
practice?

So can you make it a bit clearer in the commit message, and the code,
that this is only about enabling the generic gigantic page support, and
is unrelated to the arch-specific gigantic page support.

cheers

> diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h
> index 6666cd366596..5c28bd6f2ae1 100644
> --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h
> +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h
> @@ -50,4 +50,14 @@ static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
>  	else
>  		return entry;
>  }
> +
> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
> +static inline bool gigantic_page_supported(void)
> +{
> +	if (radix_enabled())
> +		return true;
> +	return false;
> +}
> +#endif
> +
>  #endif
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index a4f33de4008e..80f6d2ed551a 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -763,8 +763,11 @@ static int __init add_huge_page_size(unsigned long long size)
>  	 * Hash: 16M and 16G
>  	 */
>  	if (radix_enabled()) {
> -		if (mmu_psize != MMU_PAGE_2M)
> -			return -EINVAL;
> +		if (mmu_psize != MMU_PAGE_2M) {
> +			if (cpu_has_feature(CPU_FTR_POWER9_DD1) ||
> +			    (mmu_psize != MMU_PAGE_1G))
> +				return -EINVAL;
> +		}
>  	} else {
>  		if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
>  			return -EINVAL;
> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
> index 684e886eaae4..b76ef6637016 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -344,6 +344,7 @@ config PPC_STD_MMU_64
>  config PPC_RADIX_MMU
>  	bool "Radix MMU Support"
>  	depends on PPC_BOOK3S_64
> +	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
>  	default y
>  	help
>  	  Enable support for the Power ISA 3.0 Radix style MMU. Currently this
> -- 
> 2.7.4
Aneesh Kumar K.V May 18, 2017, 6:07 a.m. | #2
On Thursday 18 May 2017 10:51 AM, Michael Ellerman wrote:
> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
> 
>> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch
>> enables the usage of 1G page size for hugetlbfs. This also update the helper
>> such we can do 1G page allocation at runtime.
>>
>> We still don't enable 1G page size on DD1 version. This is to avoid doing
>> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add
>> radix__tlb_flush_pte_p9_dd1()
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> ---
>>   arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++
>>   arch/powerpc/mm/hugetlbpage.c                |  7 +++++--
>>   arch/powerpc/platforms/Kconfig.cputype       |  1 +
>>   3 files changed, 16 insertions(+), 2 deletions(-)
> 
> I think this patch is OK, but it's very confusing because it doesn't
> mention that it's only talking about *generic* gigantic page support.


What you mean by generic gigantic page ? what is supported here is the 
gigantic page with size 1G alone ?

> 
> We have existing support for gigantic pages on powerpc, on several
> platforms. This patch appears to break that, but I think doesn't in
> practice?
> 

What is broken ?


> So can you make it a bit clearer in the commit message, and the code,
> that this is only about enabling the generic gigantic page support, and
> is unrelated to the arch-specific gigantic page support.
> 
> cheers
> 
>> diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h
>> index 6666cd366596..5c28bd6f2ae1 100644
>> --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h
>> +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h
>> @@ -50,4 +50,14 @@ static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
>>   	else
>>   		return entry;
>>   }
>> +
>> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
>> +static inline bool gigantic_page_supported(void)
>> +{
>> +	if (radix_enabled())
>> +		return true;
>> +	return false;
>> +}
>> +#endif
>> +
>>   #endif
>> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
>> index a4f33de4008e..80f6d2ed551a 100644
>> --- a/arch/powerpc/mm/hugetlbpage.c
>> +++ b/arch/powerpc/mm/hugetlbpage.c
>> @@ -763,8 +763,11 @@ static int __init add_huge_page_size(unsigned long long size)
>>   	 * Hash: 16M and 16G
>>   	 */
>>   	if (radix_enabled()) {
>> -		if (mmu_psize != MMU_PAGE_2M)
>> -			return -EINVAL;
>> +		if (mmu_psize != MMU_PAGE_2M) {
>> +			if (cpu_has_feature(CPU_FTR_POWER9_DD1) ||
>> +			    (mmu_psize != MMU_PAGE_1G))
>> +				return -EINVAL;
>> +		}
>>   	} else {
>>   		if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
>>   			return -EINVAL;
>> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
>> index 684e886eaae4..b76ef6637016 100644
>> --- a/arch/powerpc/platforms/Kconfig.cputype
>> +++ b/arch/powerpc/platforms/Kconfig.cputype
>> @@ -344,6 +344,7 @@ config PPC_STD_MMU_64
>>   config PPC_RADIX_MMU
>>   	bool "Radix MMU Support"
>>   	depends on PPC_BOOK3S_64
>> +	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
>>   	default y
>>   	help
>>   	  Enable support for the Power ISA 3.0 Radix style MMU. Currently this
>> -- 
>> 2.7.4
>
Michael Ellerman May 18, 2017, 8:47 a.m. | #3
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:

> On Thursday 18 May 2017 10:51 AM, Michael Ellerman wrote:
>> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
>> 
>>> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch
>>> enables the usage of 1G page size for hugetlbfs. This also update the helper
>>> such we can do 1G page allocation at runtime.
>>>
>>> We still don't enable 1G page size on DD1 version. This is to avoid doing
>>> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add
>>> radix__tlb_flush_pte_p9_dd1()
>>>
>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>>> ---
>>>   arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++
>>>   arch/powerpc/mm/hugetlbpage.c                |  7 +++++--
>>>   arch/powerpc/platforms/Kconfig.cputype       |  1 +
>>>   3 files changed, 16 insertions(+), 2 deletions(-)
>> 
>> I think this patch is OK, but it's very confusing because it doesn't
>> mention that it's only talking about *generic* gigantic page support.
>
> What you mean by generic gigantic page ? what is supported here is the 
> gigantic page with size 1G alone ?

What about 16G pages on pseries.

And all the other gigantic page sizes that Book3E supports?

cheers
Aneesh Kumar K.V May 18, 2017, 8:50 a.m. | #4
On Thursday 18 May 2017 02:17 PM, Michael Ellerman wrote:
> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
> 
>> On Thursday 18 May 2017 10:51 AM, Michael Ellerman wrote:
>>> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
>>>
>>>> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch
>>>> enables the usage of 1G page size for hugetlbfs. This also update the helper
>>>> such we can do 1G page allocation at runtime.
>>>>
>>>> We still don't enable 1G page size on DD1 version. This is to avoid doing
>>>> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add
>>>> radix__tlb_flush_pte_p9_dd1()
>>>>
>>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>>>> ---
>>>>    arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++
>>>>    arch/powerpc/mm/hugetlbpage.c                |  7 +++++--
>>>>    arch/powerpc/platforms/Kconfig.cputype       |  1 +
>>>>    3 files changed, 16 insertions(+), 2 deletions(-)
>>>
>>> I think this patch is OK, but it's very confusing because it doesn't
>>> mention that it's only talking about *generic* gigantic page support.
>>
>> What you mean by generic gigantic page ? what is supported here is the
>> gigantic page with size 1G alone ?
> 
> What about 16G pages on pseries.
> 
> And all the other gigantic page sizes that Book3E supports?
> 

None of that is supported w.r.t runtime allocation of hugepages. ie, we 
cannot echo nr_hugepages w.r.t them.  For 16GB i am not sure it make 
sense, because we will rarely get such large contiguous region. W.r.t 
page size supported for Book3E, may be we can. But I don't have a 
facility to test those. Hence didn't include that.

-aneesh

Patch

diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h
index 6666cd366596..5c28bd6f2ae1 100644
--- a/arch/powerpc/include/asm/book3s/64/hugetlb.h
+++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h
@@ -50,4 +50,14 @@  static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 	else
 		return entry;
 }
+
+#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
+static inline bool gigantic_page_supported(void)
+{
+	if (radix_enabled())
+		return true;
+	return false;
+}
+#endif
+
 #endif
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index a4f33de4008e..80f6d2ed551a 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -763,8 +763,11 @@  static int __init add_huge_page_size(unsigned long long size)
 	 * Hash: 16M and 16G
 	 */
 	if (radix_enabled()) {
-		if (mmu_psize != MMU_PAGE_2M)
-			return -EINVAL;
+		if (mmu_psize != MMU_PAGE_2M) {
+			if (cpu_has_feature(CPU_FTR_POWER9_DD1) ||
+			    (mmu_psize != MMU_PAGE_1G))
+				return -EINVAL;
+		}
 	} else {
 		if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
 			return -EINVAL;
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 684e886eaae4..b76ef6637016 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -344,6 +344,7 @@  config PPC_STD_MMU_64
 config PPC_RADIX_MMU
 	bool "Radix MMU Support"
 	depends on PPC_BOOK3S_64
+	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
 	default y
 	help
 	  Enable support for the Power ISA 3.0 Radix style MMU. Currently this