powerpc/mm/iommu/vfio_spapr_tce: Change mm_iommu_get to reference a region

Normally mm_iommu_get() should add a reference and mm_iommu_put() should
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.

This changes mm_iommu_get() to reference the region so the name now
reflects what it does.

This removes the check for exact match from mm_iommu_new() as we want it
to fail on existing regions; mm_iommu_get() should be used instead.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index e687ed31d85ad465cb18b1a344265460168a3357..424899a7fac87dbd22e1b66c07de4d573ca94ec7 100644 (file)
--- 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 56c2234cc6ae70b8c7c27c64897bb3560ad86219..ce8cc69f7901f9afc524ee92a4e8597098d81dde 100644 (file)
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -126,7 +126,7 @@ static int mm_iommu_move_page_from_cma(struct page *page)
        return 0;
 }
 
-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;
@@ -140,12 +140,6 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 
        list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
                        next) {
-               if ((mem->ua == ua) && (mem->entries == entries)) {
-                       ++mem->used;
-                       *pmem = mem;
-                       goto unlock_exit;
-               }
-
                /* Overlap? */
                if ((mem->ua < (ua + (entries << PAGE_SHIFT))) &&
                                (ua < (mem->ua +
@@ -252,7 +246,7 @@ unlock_exit:
 
        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)
 {
@@ -368,21 +362,26 @@ 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 ad637250938d5559f6e12d453d282ad6ea567087..1d8b889283298b15e3e99eae91add0c5c7ae45ec 100644 (file)
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -152,11 +152,12 @@ 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;
+       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);
+
+       mm_iommu_put(container->mm, mem);
 
-       return tce_iommu_prereg_free(container, tcemem);
+       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)