[PATCH V3 3/3] s390/mm: Define arch_get_mappable_range()

[Anshuman Khandual]

On 1/19/21 5:56 PM, David Hildenbrand wrote:
> On 18.01.21 14:13, Anshuman Khandual wrote:
>> This overrides arch_get_mappabble_range() on s390 platform which will be
>> used with recently added generic framework. It modifies the existing range
>> check in vmem_add_mapping() using arch_get_mappable_range(). It also adds a
>> VM_BUG_ON() check that would ensure that memhp_range_allowed() has already
>> been called on the hotplug path.
>>
>> Cc: Heiko Carstens <hca at linux.ibm.com>
>> Cc: Vasily Gorbik <gor at linux.ibm.com>
>> Cc: David Hildenbrand <david at redhat.com>
>> Cc: linux-s390 at vger.kernel.org
>> Cc: linux-kernel at vger.kernel.org
>> Acked-by: Heiko Carstens <hca at linux.ibm.com>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com>
>> ---
>>  arch/s390/mm/init.c |  1 +
>>  arch/s390/mm/vmem.c | 15 ++++++++++++++-
>>  2 files changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
>> index 73a163065b95..97017a4bcc90 100644
>> --- a/arch/s390/mm/init.c
>> +++ b/arch/s390/mm/init.c
>> @@ -297,6 +297,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
>>  	if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
>>  		return -EINVAL;
>>  
>> +	VM_BUG_ON(!memhp_range_allowed(start, size, true));
>>  	rc = vmem_add_mapping(start, size);
>>  	if (rc)
>>  		return rc;
>> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
>> index 01f3a5f58e64..afc39ff1cc8d 100644
>> --- a/arch/s390/mm/vmem.c
>> +++ b/arch/s390/mm/vmem.c
>> @@ -4,6 +4,7 @@
>>   *    Author(s): Heiko Carstens <heiko.carstens at de.ibm.com>
>>   */
>>  
>> +#include <linux/memory_hotplug.h>
>>  #include <linux/memblock.h>
>>  #include <linux/pfn.h>
>>  #include <linux/mm.h>
>> @@ -532,11 +533,23 @@ void vmem_remove_mapping(unsigned long start, unsigned long size)
>>  	mutex_unlock(&vmem_mutex);
>>  }
>>  
>> +struct range arch_get_mappable_range(void)
>> +{
>> +	struct range memhp_range;
> 
> You could do:
> 
> memhp_range = {
> 	.start = 0,
> 	.end =  VMEM_MAX_PHYS - 1,
> };
> 
> Similar in the arm64 patch.

There is a comment block just before this assignment on arm64. Also
it seems like code style preference and Heiko had originally agreed
on this particular patch. Could we just leave it unchanged please ?

> 
>> +
>> +	memhp_range.start = 0;
>> +	memhp_range.end =  VMEM_MAX_PHYS - 1;
>> +	return memhp_range;
>> +}
>> +
>>  int vmem_add_mapping(unsigned long start, unsigned long size)
>>  {
>> +	struct range range;
>>  	int ret;
>>  
>> -	if (start + size > VMEM_MAX_PHYS ||
>> +	range = arch_get_mappable_range();
> 
> You could do
> 
> struct range range = arch_get_mappable_range();

Sure, will change this though.

> 
>> +	if (start < range.start ||
>> +	    start + size > range.end + 1 ||
>>  	    start + size < start)
>>  		return -ERANGE;
>>  
>>
> 
>