Re: [PATCH] KVM: arm64: Drop sort_memblock_regions()

[Gavin Shan <gshan@redhat.com>]

On 3/13/25 12:53 PM, Anshuman Khandual wrote:
> On 3/11/25 10:07, Gavin Shan wrote:
>> Drop sort_memblock_regions() and avoid sorting the copied memory
>> regions to be ascending order on their base addresses, because the
>> source memory regions should have been sorted correctly when they
>> are added by memblock_add() or its variants.
>>
>> This is generally reverting commit a14307f5310c ("KVM: arm64: Sort
>> the hypervisor memblocks"). No functional changes intended.
> 
> Just wondering what prompted this change ?
> 

I found the unnecessary sorting by code inspection. Hope there is nothing I
missed and it's why Quentin Perret has been copied, to confirm it. Commit
a14307f5310c was introduced by the initial series [1/2] to support pKVM.

[1] https://lore.kernel.org/kvmarm/20201117181607.1761516-1-qperret@google.com/
[2] https://lore.kernel.org/all/20210319100146.1149909-1-qperret@google.com/

Thanks,
Gavin

>>
>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>> ---
>>   arch/arm64/kvm/pkvm.c | 19 -------------------
>>   1 file changed, 19 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
>> index 930b677eb9b0..d9c9174f89a1 100644
>> --- a/arch/arm64/kvm/pkvm.c
>> +++ b/arch/arm64/kvm/pkvm.c
>> @@ -10,7 +10,6 @@
>>   #include <asm/kvm_mmu.h>
>>   #include <linux/memblock.h>
>>   #include <linux/mutex.h>
>> -#include <linux/sort.h>
>>   
>>   #include <asm/kvm_pkvm.h>
>>   
>> @@ -24,23 +23,6 @@ static unsigned int *hyp_memblock_nr_ptr = &kvm_nvhe_sym(hyp_memblock_nr);
>>   phys_addr_t hyp_mem_base;
>>   phys_addr_t hyp_mem_size;
>>   
>> -static int cmp_hyp_memblock(const void *p1, const void *p2)
>> -{
>> -	const struct memblock_region *r1 = p1;
>> -	const struct memblock_region *r2 = p2;
>> -
>> -	return r1->base < r2->base ? -1 : (r1->base > r2->base);
>> -}
>> -
>> -static void __init sort_memblock_regions(void)
>> -{
>> -	sort(hyp_memory,
>> -	     *hyp_memblock_nr_ptr,
>> -	     sizeof(struct memblock_region),
>> -	     cmp_hyp_memblock,
>> -	     NULL);
>> -}
>> -
>>   static int __init register_memblock_regions(void)
>>   {
>>   	struct memblock_region *reg;
>> @@ -52,7 +34,6 @@ static int __init register_memblock_regions(void)
>>   		hyp_memory[*hyp_memblock_nr_ptr] = *reg;
>>   		(*hyp_memblock_nr_ptr)++;
>>   	}
>> -	sort_memblock_regions();
>>   
>>   	return 0;
>>   }
>