On Mon, Mar 07, 2016 at 02:41:10PM +1100, Alexey Kardashevskiy wrote:
> This makes mm_iommu_lookup() able to work in realmode by replacing
> list_for_each_entry_rcu() (which can do debug stuff which can fail in
> real mode) with list_for_each_entry_lockless().
>
> This adds realmode version of mm_iommu_ua_to_hpa() which adds
> explicit vmalloc'd-to-linear address conversion.
> Unlike mm_iommu_ua_to_hpa(), mm_iommu_rm_ua_to_hpa() can fail.
>
> This changes mm_iommu_preregistered() to receive @mm as in real mode
> @current does not always have a correct pointer.
So, I'd generally expect a parameter called @mm to be an mm_struct *,
not a mm_context_t.
>
> This adds realmode version of mm_iommu_lookup() which receives @mm
> (for the same reason as for mm_iommu_preregistered()) and uses
> lockless version of list_for_each_entry_rcu().
>
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> ---
> arch/powerpc/include/asm/mmu_context.h | 6 ++++-
> arch/powerpc/mm/mmu_context_iommu.c | 45 ++++++++++++++++++++++++++++++----
> 2 files changed, 45 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
> index 878c277..3ba652a 100644
> --- a/arch/powerpc/include/asm/mmu_context.h
> +++ b/arch/powerpc/include/asm/mmu_context.h
> @@ -18,7 +18,7 @@ extern void destroy_context(struct mm_struct *mm);
> #ifdef CONFIG_SPAPR_TCE_IOMMU
> struct mm_iommu_table_group_mem_t;
>
> -extern bool mm_iommu_preregistered(void);
> +extern bool mm_iommu_preregistered(mm_context_t *mm);
> extern long mm_iommu_get(unsigned long ua, unsigned long entries,
> struct mm_iommu_table_group_mem_t **pmem);
> extern long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem);
> @@ -26,10 +26,14 @@ extern void mm_iommu_init(mm_context_t *ctx);
> extern void mm_iommu_cleanup(mm_context_t *ctx);
> extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
> unsigned long size);
> +extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(mm_context_t *mm,
> + unsigned long ua, unsigned long size);
> extern struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
> unsigned long entries);
> extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
> unsigned long ua, unsigned long *hpa);
> +extern long mm_iommu_rm_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
> + unsigned long ua, unsigned long *hpa);
> extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
> extern void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem);
> #endif
> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
> index da6a216..aa1565d 100644
> --- a/arch/powerpc/mm/mmu_context_iommu.c
> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> @@ -63,12 +63,9 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
> return ret;
> }
>
> -bool mm_iommu_preregistered(void)
> +bool mm_iommu_preregistered(mm_context_t *mm)
> {
> - if (!current || !current->mm)
> - return false;
> -
> - return !list_empty(¤t->mm->context.iommu_group_mem_list);
> + return !list_empty(&mm->iommu_group_mem_list);
> }
> EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
>
> @@ -231,6 +228,24 @@ unlock_exit:
> }
> EXPORT_SYMBOL_GPL(mm_iommu_put);
>
> +struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(mm_context_t *mm,
> + unsigned long ua, unsigned long size)
> +{
> + struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
I think you could do with a comment here explaining why the lockless
traversal is safe.
> + list_for_each_entry_lockless(mem, &mm->iommu_group_mem_list, next) {
> + if ((mem->ua <= ua) &&
> + (ua + size <= mem->ua +
> + (mem->entries << PAGE_SHIFT))) {
> + ret = mem;
> + break;
> + }
> + }
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(mm_iommu_lookup_rm);
> +
> struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
> unsigned long size)
> {
> @@ -284,6 +299,26 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
> }
> EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
>
> +long mm_iommu_rm_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
> + unsigned long ua, unsigned long *hpa)
> +{
> + const long entry = (ua - mem->ua) >> PAGE_SHIFT;
> + void *va = &mem->hpas[entry];
> + unsigned long *ra;
> +
> + if (entry >= mem->entries)
> + return -EFAULT;
> +
> + ra = (void *) vmalloc_to_phys(va);
> + if (!ra)
> + return -EFAULT;
> +
> + *hpa = *ra | (ua & ~PAGE_MASK);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(mm_iommu_rm_ua_to_hpa);
> +
> long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
> {
> if (atomic64_inc_not_zero(&mem->mapped))
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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