Re: [PATCH v5 04/14] KVM: arm64: Don't pass kvm_pgtable through kvm_pgtable_walk_data

[Gavin Shan <gshan@redhat.com>]

Hi Oliver,

On 11/8/22 5:56 AM, Oliver Upton wrote:
> In order to tear down page tables from outside the context of
> kvm_pgtable (such as an RCU callback), stop passing a pointer through
> kvm_pgtable_walk_data.
> 
> No functional change intended.
> 
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> ---
>   arch/arm64/kvm/hyp/pgtable.c | 18 +++++-------------
>   1 file changed, 5 insertions(+), 13 deletions(-)
> 

Reviewed-by: Gavin Shan <gshan@redhat.com>

> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index db25e81a9890..93989b750a26 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -50,7 +50,6 @@
>   #define KVM_MAX_OWNER_ID		1
>   
>   struct kvm_pgtable_walk_data {
> -	struct kvm_pgtable		*pgt;
>   	struct kvm_pgtable_walker	*walker;
>   
>   	u64				addr;

Ok. Here is the answer why data->pgt->mm_ops isn't reachable in the walker
and visitor, and @mm_ops needs to be passed down.

> @@ -88,7 +87,7 @@ static u32 kvm_pgtable_idx(struct kvm_pgtable_walk_data *data, u32 level)
>   	return (data->addr >> shift) & mask;
>   }
>   
> -static u32 __kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr)
> +static u32 kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr)
>   {
>   	u64 shift = kvm_granule_shift(pgt->start_level - 1); /* May underflow */
>   	u64 mask = BIT(pgt->ia_bits) - 1;
> @@ -96,11 +95,6 @@ static u32 __kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr)
>   	return (addr & mask) >> shift;
>   }
>   
> -static u32 kvm_pgd_page_idx(struct kvm_pgtable_walk_data *data)
> -{
> -	return __kvm_pgd_page_idx(data->pgt, data->addr);
> -}
> -
>   static u32 kvm_pgd_pages(u32 ia_bits, u32 start_level)
>   {
>   	struct kvm_pgtable pgt = {
> @@ -108,7 +102,7 @@ static u32 kvm_pgd_pages(u32 ia_bits, u32 start_level)
>   		.start_level	= start_level,
>   	};
>   
> -	return __kvm_pgd_page_idx(&pgt, -1ULL) + 1;
> +	return kvm_pgd_page_idx(&pgt, -1ULL) + 1;
>   }
>   
>   static bool kvm_pte_table(kvm_pte_t pte, u32 level)
> @@ -255,11 +249,10 @@ static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data,
>   	return ret;
>   }
>   
> -static int _kvm_pgtable_walk(struct kvm_pgtable_walk_data *data)
> +static int _kvm_pgtable_walk(struct kvm_pgtable *pgt, struct kvm_pgtable_walk_data *data)
>   {
>   	u32 idx;
>   	int ret = 0;
> -	struct kvm_pgtable *pgt = data->pgt;
>   	u64 limit = BIT(pgt->ia_bits);
>   
>   	if (data->addr > limit || data->end > limit)
> @@ -268,7 +261,7 @@ static int _kvm_pgtable_walk(struct kvm_pgtable_walk_data *data)
>   	if (!pgt->pgd)
>   		return -EINVAL;
>   
> -	for (idx = kvm_pgd_page_idx(data); data->addr < data->end; ++idx) {
> +	for (idx = kvm_pgd_page_idx(pgt, data->addr); data->addr < data->end; ++idx) {
>   		kvm_pte_t *ptep = &pgt->pgd[idx * PTRS_PER_PTE];
>   
>   		ret = __kvm_pgtable_walk(data, pgt->mm_ops, ptep, pgt->start_level);
> @@ -283,13 +276,12 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
>   		     struct kvm_pgtable_walker *walker)
>   {
>   	struct kvm_pgtable_walk_data walk_data = {
> -		.pgt	= pgt,
>   		.addr	= ALIGN_DOWN(addr, PAGE_SIZE),
>   		.end	= PAGE_ALIGN(walk_data.addr + size),
>   		.walker	= walker,
>   	};
>   
> -	return _kvm_pgtable_walk(&walk_data);
> +	return _kvm_pgtable_walk(pgt, &walk_data);
>   }
>   
>   struct leaf_walk_data {
> 

Thanks,
Gavin


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel