[PATCH kernel v3 02/22] powerpc/mm/iommu/vfio_spapr_tce: Change mm_iommu_get to reference a region
David Gibson
david at gibson.dropbear.id.au
Thu Nov 15 16:32:50 AEDT 2018
On Tue, Nov 13, 2018 at 07:28:03PM +1100, Alexey Kardashevskiy wrote:
> Normally mm_iommu_get() is supposed to add a reference and
> mm_iommu_put() to remove it. However historically mm_iommu_find() does
> the referencing and mm_iommu_get() is doing allocation and referencing.
>
> We are going to add another helper to preregister device memory so
> instead of having mm_iommu_new() which pre-registers the normal memory
> and references the region, we need separate helpers for pre-registering
> and referencing.
>
> This renames:
> - mm_iommu_get to mm_iommu_new;
> - mm_iommu_find to mm_iommu_get.
>
> To make the mm_iommu_get name reflect what it is supposed to do, this
> changes mm_iommu_get() to reference the region so from now on for every
> mm_iommu_get() we need a matching mm_iommu_put().
>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
Reviewed-by: David Gibson <david at gibson.dropbear.id.au>
> ---
> Changes:
> v2:
> * merged 2 patches into one
> ---
> arch/powerpc/include/asm/mmu_context.h | 4 +--
> arch/powerpc/mm/mmu_context_iommu.c | 13 ++++++---
> drivers/vfio/vfio_iommu_spapr_tce.c | 37 +++++++++++++++++---------
> 3 files changed, 35 insertions(+), 19 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
> index 0381394..2d6b00d 100644
> --- a/arch/powerpc/include/asm/mmu_context.h
> +++ b/arch/powerpc/include/asm/mmu_context.h
> @@ -21,7 +21,7 @@ struct mm_iommu_table_group_mem_t;
>
> extern int isolate_lru_page(struct page *page); /* from internal.h */
> extern bool mm_iommu_preregistered(struct mm_struct *mm);
> -extern long mm_iommu_get(struct mm_struct *mm,
> +extern long mm_iommu_new(struct mm_struct *mm,
> unsigned long ua, unsigned long entries,
> struct mm_iommu_table_group_mem_t **pmem);
> extern long mm_iommu_put(struct mm_struct *mm,
> @@ -32,7 +32,7 @@ extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
> unsigned long ua, unsigned long size);
> extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(
> struct mm_struct *mm, unsigned long ua, unsigned long size);
> -extern struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
> +extern struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
> 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 int pageshift, unsigned long *hpa);
> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
> index 1d5161f..babc6ad 100644
> --- a/arch/powerpc/mm/mmu_context_iommu.c
> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> @@ -89,7 +89,7 @@ bool mm_iommu_preregistered(struct mm_struct *mm)
> }
> EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
>
> -long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
> +long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
> struct mm_iommu_table_group_mem_t **pmem)
> {
> struct mm_iommu_table_group_mem_t *mem;
> @@ -202,7 +202,7 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
>
> return ret;
> }
> -EXPORT_SYMBOL_GPL(mm_iommu_get);
> +EXPORT_SYMBOL_GPL(mm_iommu_new);
>
> static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
> {
> @@ -318,21 +318,26 @@ struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
> return ret;
> }
>
> -struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
> +struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
> unsigned long ua, unsigned long entries)
> {
> struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
>
> + mutex_lock(&mem_list_mutex);
> +
> list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
> if ((mem->ua == ua) && (mem->entries == entries)) {
> ret = mem;
> + ++mem->used;
> break;
> }
> }
>
> + mutex_unlock(&mem_list_mutex);
> +
> return ret;
> }
> -EXPORT_SYMBOL_GPL(mm_iommu_find);
> +EXPORT_SYMBOL_GPL(mm_iommu_get);
>
> long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
> unsigned long ua, unsigned int pageshift, unsigned long *hpa)
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index ad63725..56db071 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -151,12 +151,13 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
> {
> struct mm_iommu_table_group_mem_t *mem;
> struct tce_iommu_prereg *tcemem;
> - bool found = false;
> + bool found;
> + long ret;
>
> if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
> return -EINVAL;
>
> - mem = mm_iommu_find(container->mm, vaddr, size >> PAGE_SHIFT);
> + mem = mm_iommu_get(container->mm, vaddr, size >> PAGE_SHIFT);
> if (!mem)
> return -ENOENT;
>
> @@ -168,9 +169,13 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
> }
>
> if (!found)
> - return -ENOENT;
> + ret = -ENOENT;
> + else
> + ret = tce_iommu_prereg_free(container, tcemem);
>
> - return tce_iommu_prereg_free(container, tcemem);
> + mm_iommu_put(container->mm, mem);
> +
> + return ret;
> }
>
> static long tce_iommu_register_pages(struct tce_container *container,
> @@ -185,22 +190,24 @@ static long tce_iommu_register_pages(struct tce_container *container,
> ((vaddr + size) < vaddr))
> return -EINVAL;
>
> - mem = mm_iommu_find(container->mm, vaddr, entries);
> + mem = mm_iommu_get(container->mm, vaddr, entries);
> if (mem) {
> list_for_each_entry(tcemem, &container->prereg_list, next) {
> - if (tcemem->mem == mem)
> - return -EBUSY;
> + if (tcemem->mem == mem) {
> + ret = -EBUSY;
> + goto put_exit;
> + }
> }
> + } else {
> + ret = mm_iommu_new(container->mm, vaddr, entries, &mem);
> + if (ret)
> + return ret;
> }
>
> - ret = mm_iommu_get(container->mm, vaddr, entries, &mem);
> - if (ret)
> - return ret;
> -
> tcemem = kzalloc(sizeof(*tcemem), GFP_KERNEL);
> if (!tcemem) {
> - mm_iommu_put(container->mm, mem);
> - return -ENOMEM;
> + ret = -ENOMEM;
> + goto put_exit;
> }
>
> tcemem->mem = mem;
> @@ -209,6 +216,10 @@ static long tce_iommu_register_pages(struct tce_container *container,
> container->enabled = true;
>
> return 0;
> +
> +put_exit:
> + mm_iommu_put(container->mm, mem);
> + return ret;
> }
>
> static bool tce_page_is_contained(struct page *page, unsigned page_shift)
--
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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