[PATCH kernel v4 01/10] powerpc/mmu: Add real mode support for IOMMU preregistered memory

Alexey Kardashevskiy
2017-02-07T07:17:30Z

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_ua_to_hpa_rm() can fail.

This changes mm_iommu_preregistered() to receive @mm as in real mode
@current does not always have a correct pointer.

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@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---
arch/powerpc/include/asm/mmu_context.h | 4 ++++
arch/powerpc/mm/mmu_context_iommu.c | 39 ++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index b9e3f0aca261..c70c8272523d 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -29,10 +29,14 @@ extern void mm_iommu_init(struct mm_struct *mm);
extern void mm_iommu_cleanup(struct mm_struct *mm);
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,
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_ua_to_hpa_rm(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 104bad029ce9..631d32f5937b 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -314,6 +314,25 @@ struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
}
EXPORT_SYMBOL_GPL(mm_iommu_lookup);

+struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
+ unsigned long ua, unsigned long size)
+{
+ struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
+
+ list_for_each_entry_lockless(mem, &mm->context.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_find(struct mm_struct *mm,
unsigned long ua, unsigned long entries)
{
@@ -345,6 +364,26 @@ 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_ua_to_hpa_rm(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 *pa;
+
+ if (entry >= mem->entries)
+ return -EFAULT;
+
+ pa = (void *) vmalloc_to_phys(va);
+ if (!pa)
+ return -EFAULT;
+
+ *hpa = *pa | (ua & ~PAGE_MASK);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa_rm);
+
long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
{
if (atomic64_inc_not_zero(&mem->mapped))
--
2.11.0