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From: Marc Zyngier <maz@kernel.org>
To: Gavin Shan <gshan@redhat.com>
Cc: will@kernel.org, kvmarm@lists.cs.columbia.edu,
	shan.gavin@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] KVM: arm64: Use find_vma_intersection()
Date: Mon, 15 Mar 2021 08:52:38 +0000	[thread overview]
Message-ID: <87eeggg5nt.wl-maz@kernel.org> (raw)
In-Reply-To: <20210315041844.64915-3-gshan@redhat.com>

On Mon, 15 Mar 2021 04:18:42 +0000,
Gavin Shan <gshan@redhat.com> 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@redhat.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);

For context, here's the definition of find_vma_intersection():

<quote>
static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * mm, unsigned long start_addr, unsigned long end_addr)
{
	struct vm_area_struct * vma = find_vma(mm,start_addr);

	if (vma && end_addr <= vma->vm_start)
		vma = NULL;
	return vma;
}
</quote>

It seems that there is a boundary issue in either the old code or the
new one in the case where (reg_end == vma->start).

Which one is which?

	M.

-- 
Without deviation from the norm, progress is not possible.
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WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Gavin Shan <gshan@redhat.com>
Cc: kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
	will@kernel.org, alexandru.elisei@arm.com, shan.gavin@gmail.com
Subject: Re: [PATCH 2/4] KVM: arm64: Use find_vma_intersection()
Date: Mon, 15 Mar 2021 08:52:38 +0000	[thread overview]
Message-ID: <87eeggg5nt.wl-maz@kernel.org> (raw)
In-Reply-To: <20210315041844.64915-3-gshan@redhat.com>

On Mon, 15 Mar 2021 04:18:42 +0000,
Gavin Shan <gshan@redhat.com> 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@redhat.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);

For context, here's the definition of find_vma_intersection():

<quote>
static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * mm, unsigned long start_addr, unsigned long end_addr)
{
	struct vm_area_struct * vma = find_vma(mm,start_addr);

	if (vma && end_addr <= vma->vm_start)
		vma = NULL;
	return vma;
}
</quote>

It seems that there is a boundary issue in either the old code or the
new one in the case where (reg_end == vma->start).

Which one is which?

	M.

-- 
Without deviation from the norm, progress is not possible.

  parent reply	other threads:[~2021-03-15  8:52 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-15  4:18 [PATCH 0/4] KVM: arm64: Minor page fault handler improvement Gavin Shan
2021-03-15  4:18 ` Gavin Shan
2021-03-15  4:18 ` [PATCH 1/4] KVM: arm64: Hide kvm_mmu_wp_memory_region() Gavin Shan
2021-03-15  4:18   ` Gavin Shan
2021-03-15  7:49   ` Keqian Zhu
2021-03-15  7:49     ` Keqian Zhu
2021-03-15  4:18 ` [PATCH 2/4] KVM: arm64: Use find_vma_intersection() Gavin Shan
2021-03-15  4:18   ` Gavin Shan
2021-03-15  8:04   ` Keqian Zhu
2021-03-15  8:04     ` Keqian Zhu
2021-03-15  9:42     ` Gavin Shan
2021-03-15  9:42       ` Gavin Shan
2021-03-16  3:52       ` Gavin Shan
2021-03-16  3:52         ` Gavin Shan
2021-03-16  4:20         ` Keqian Zhu
2021-03-16  4:20           ` Keqian Zhu
2021-03-15  8:52   ` Marc Zyngier [this message]
2021-03-15  8:52     ` Marc Zyngier
2021-03-15  9:40     ` Gavin Shan
2021-03-15  9:40       ` Gavin Shan
2021-03-15  4:18 ` [PATCH 3/4] KVM: arm64: Fix address check for memory slot Gavin Shan
2021-03-15  4:18   ` Gavin Shan
2021-03-15  7:33   ` Keqian Zhu
2021-03-15  7:33     ` Keqian Zhu
2021-03-15  9:46     ` Gavin Shan
2021-03-15  9:46       ` Gavin Shan
2021-03-15  4:18 ` [PATCH 4/4] KVM: arm64: Don't retrieve memory slot again in page fault handler Gavin Shan
2021-03-15  4:18   ` Gavin Shan
2021-03-15  8:25   ` Keqian Zhu
2021-03-15  8:25     ` Keqian Zhu
2021-03-15  9:56     ` Gavin Shan
2021-03-15  9:56       ` Gavin Shan
2021-03-15 10:46       ` Keqian Zhu
2021-03-15 10:46         ` Keqian Zhu

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