[v3,4/7] x86/mm: Introduce _set_memory_prot()
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Message ID 20200221182503.28317-5-logang@deltatee.com
State New
Headers show
Series
  • Allow setting caching mode in arch_add_memory() for P2PDMA
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Commit Message

Logan Gunthorpe Feb. 21, 2020, 6:25 p.m. UTC
For use in the 32bit arch_add_memory() to set the pgprot type of the
memory to add.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
 arch/x86/include/asm/set_memory.h | 1 +
 arch/x86/mm/pat/set_memory.c      | 7 +++++++
 2 files changed, 8 insertions(+)

Comments

Dan Williams Feb. 29, 2020, 10:33 p.m. UTC | #1
On Fri, Feb 21, 2020 at 10:25 AM Logan Gunthorpe <logang@deltatee.com> wrote:
>
> For use in the 32bit arch_add_memory() to set the pgprot type of the
> memory to add.
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: x86@kernel.org
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> ---
>  arch/x86/include/asm/set_memory.h | 1 +
>  arch/x86/mm/pat/set_memory.c      | 7 +++++++
>  2 files changed, 8 insertions(+)
>
> diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
> index 64c3dce374e5..0aca959cf9a4 100644
> --- a/arch/x86/include/asm/set_memory.h
> +++ b/arch/x86/include/asm/set_memory.h
> @@ -34,6 +34,7 @@
>   * The caller is required to take care of these.
>   */
>
> +int _set_memory_prot(unsigned long addr, int numpages, pgprot_t prot);

I wonder if this should be separated from the naming convention of the
other routines because this is only an internal helper for code paths
where the prot was established by an upper layer. For example, I
expect that the kernel does not want new usages to make the mistake of
calling:

   _set_memory_prot(..., pgprot_writecombine(pgprot))

...instead of

    _set_memory_wc()

I'm thinking just a double underscore rename (__set_memory_prot) and a
kerneldoc comment for that  pointing people to use the direct
_set_memory_<cachemode> helpers.

With that you can add:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Logan Gunthorpe March 2, 2020, 6:46 p.m. UTC | #2
On 2020-02-29 3:33 p.m., Dan Williams wrote:
> On Fri, Feb 21, 2020 at 10:25 AM Logan Gunthorpe <logang@deltatee.com> wrote:
>>
>> For use in the 32bit arch_add_memory() to set the pgprot type of the
>> memory to add.
>>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: "H. Peter Anvin" <hpa@zytor.com>
>> Cc: x86@kernel.org
>> Cc: Dave Hansen <dave.hansen@linux.intel.com>
>> Cc: Andy Lutomirski <luto@kernel.org>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
>> ---
>>  arch/x86/include/asm/set_memory.h | 1 +
>>  arch/x86/mm/pat/set_memory.c      | 7 +++++++
>>  2 files changed, 8 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
>> index 64c3dce374e5..0aca959cf9a4 100644
>> --- a/arch/x86/include/asm/set_memory.h
>> +++ b/arch/x86/include/asm/set_memory.h
>> @@ -34,6 +34,7 @@
>>   * The caller is required to take care of these.
>>   */
>>
>> +int _set_memory_prot(unsigned long addr, int numpages, pgprot_t prot);
> 
> I wonder if this should be separated from the naming convention of the
> other routines because this is only an internal helper for code paths
> where the prot was established by an upper layer. For example, I
> expect that the kernel does not want new usages to make the mistake of
> calling:
> 
>    _set_memory_prot(..., pgprot_writecombine(pgprot))
> 
> ...instead of
> 
>     _set_memory_wc()
> 
> I'm thinking just a double underscore rename (__set_memory_prot) and a
> kerneldoc comment for that  pointing people to use the direct
> _set_memory_<cachemode> helpers.

Thanks! Will do. Note, though, that even _set_memory_wc() is an internal
x86-specific function. But the extra comment and underscore still make
sense.

> With that you can add:
> 
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>

Patch
diff mbox series

diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 64c3dce374e5..0aca959cf9a4 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -34,6 +34,7 @@ 
  * The caller is required to take care of these.
  */
 
+int _set_memory_prot(unsigned long addr, int numpages, pgprot_t prot);
 int _set_memory_uc(unsigned long addr, int numpages);
 int _set_memory_wc(unsigned long addr, int numpages);
 int _set_memory_wt(unsigned long addr, int numpages);
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index c4aedd00c1ba..2ba83d53d835 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1792,6 +1792,13 @@  static inline int cpa_clear_pages_array(struct page **pages, int numpages,
 		CPA_PAGES_ARRAY, pages);
 }
 
+int _set_memory_prot(unsigned long addr, int numpages, pgprot_t prot)
+{
+	return change_page_attr_set_clr(&addr, numpages, prot,
+					__pgprot(~pgprot_val(prot)), 0, 0,
+					NULL);
+}
+
 int _set_memory_uc(unsigned long addr, int numpages)
 {
 	/*