linux-kernel - Re: [PATCH 2/4] KVM: arm64: Use find_vma

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Date:   Tue, 16 Mar 2021 14:52:28 +1100
From:   Gavin Shan <gshan@...hat.com>
To:     Keqian Zhu <zhukeqian1@...wei.com>, kvmarm@...ts.cs.columbia.edu
Cc:     maz@...nel.org, will@...nel.org, linux-kernel@...r.kernel.org,
        shan.gavin@...il.com
Subject: Re: [PATCH 2/4] KVM: arm64: Use find_vma_intersection()

Hi Keqian,

On 3/15/21 8:42 PM, Gavin Shan wrote:
> On 3/15/21 7:04 PM, Keqian Zhu wrote:
>> On 2021/3/15 12:18, Gavin Shan wrote:
>>> find_vma_intersection() has been existing to search the intersected
>>> vma. This uses the function where it's applicable, to simplify the
>>> code.
>>>
>>> Signed-off-by: Gavin Shan <gshan@...hat.com>
>>> ---
>>>   arch/arm64/kvm/mmu.c | 10 ++++++----
>>>   1 file changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
>>> index 84e70f953de6..286b603ed0d3 100644
>>> --- a/arch/arm64/kvm/mmu.c
>>> +++ b/arch/arm64/kvm/mmu.c
>>> @@ -421,10 +421,11 @@ static void stage2_unmap_memslot(struct kvm *kvm,
>>>        *     +--------------------------------------------+
>>>        */
>>>       do {
>>> -        struct vm_area_struct *vma = find_vma(current->mm, hva);
>>> +        struct vm_area_struct *vma;
>>>           hva_t vm_start, vm_end;
>>> -        if (!vma || vma->vm_start >= reg_end)
>>> +        vma = find_vma_intersection(current->mm, hva, reg_end);
>> Nit: Keep a same style may be better(Assign vma when declare it).
>> Other looks good to me.
>>
> 
> Yeah, I agree. I will adjust the code in v2 and included your r-b.
> Thanks for your time to review.
> 

After rechecking the code, I think it'd better to keep current style
because there is a follow-on validation on @vma. Keeping them together
seems a good idea. I think it wouldn't a big deal to you. So I will
keep current style with your r-b in v2.

	vma = find_vma_intersection(current->mm, hva, reg_end);
         if (!vma)
              break;
Thanks,
Gavin
  
>>> +        if (!vma)
>>>               break;
>>>           /*
>>> @@ -1330,10 +1331,11 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
>>>        *     +--------------------------------------------+
>>>        */
>>>       do {
>>> -        struct vm_area_struct *vma = find_vma(current->mm, hva);
>>> +        struct vm_area_struct *vma;
>>>           hva_t vm_start, vm_end;
>>> -        if (!vma || vma->vm_start >= reg_end)
>>> +        vma = find_vma_intersection(current->mm, hva, reg_end);
>>> +        if (!vma)
>>>               break;
>>>           /*
>>>
>>
>