In some situations the userspace memory context may live longer than
the userspace process itself so if we need to do proper memory context
cleanup, we better cache @mm and use it later when the process is gone
(@current or @current->mm are NULL).
This changes mm_iommu_xxx API to receive mm_struct instead of using one
from @current.
This references and caches MM once per container so we do not depend
on @current pointing to a valid task descriptor anymore.
This is needed by the following patch to do proper cleanup in time.
This depends on "powerpc/powernv/ioda: Fix endianness when reading TCEs"
to do proper cleanup via tce_iommu_clear() patch.
To keep API consistent, this replaces mm_context_t with mm_struct;
we stick to mm_struct as mm_iommu_adjust_locked_vm() helper needs
access to &mm->mmap_sem.
This should cause no behavioral change.
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Reviewed-by: Nicholas Piggin <npig...@gmail.com>
Acked-by: Balbir Singh <bsinghar...@gmail.com>
---
Changes:
v2:
* added BUG_ON(container->mm && (container->mm != current->mm)) in
tce_iommu_register_pages()
* added note about containers referencing MM
---
arch/powerpc/include/asm/mmu_context.h | 20 +++++++------
arch/powerpc/kernel/setup-common.c | 2 +-
arch/powerpc/mm/mmu_context_book3s64.c | 4 +--
arch/powerpc/mm/mmu_context_iommu.c | 55 ++++++++++++++--------------------
drivers/vfio/vfio_iommu_spapr_tce.c | 41 ++++++++++++++++---------
5 files changed, 63 insertions(+), 59 deletions(-)
diff --git a/arch/powerpc/include/asm/mmu_context.h
b/arch/powerpc/include/asm/mmu_context.h
index 5c45114..b9e3f0a 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -19,16 +19,18 @@ extern void destroy_context(struct mm_struct *mm);
struct mm_iommu_table_group_mem_t;
extern int isolate_lru_page(struct page *page); /* from internal.h */
-extern bool mm_iommu_preregistered(void);
-extern long mm_iommu_get(unsigned long ua, unsigned long entries,
+extern bool mm_iommu_preregistered(struct mm_struct *mm);
+extern long mm_iommu_get(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_iommu_table_group_mem_t *mem);
-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_find(unsigned long ua,
- unsigned long entries);
+extern long mm_iommu_put(struct mm_struct *mm,
+ struct mm_iommu_table_group_mem_t *mem);
+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_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_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
diff --git a/arch/powerpc/kernel/setup-common.c
b/arch/powerpc/kernel/setup-common.c
index dba265c..942cf49 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -906,7 +906,7 @@ void __init setup_arch(char **cmdline_p)
init_mm.context.pte_frag = NULL;
#endif
#ifdef CONFIG_SPAPR_TCE_IOMMU
- mm_iommu_init(&init_mm.context);
+ mm_iommu_init(&init_mm);
#endif
irqstack_early_init();
exc_lvl_early_init();
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c
b/arch/powerpc/mm/mmu_context_book3s64.c
index b114f8b..ad82735 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -115,7 +115,7 @@ int init_new_context(struct task_struct *tsk, struct
mm_struct *mm)
mm->context.pte_frag = NULL;
#endif
#ifdef CONFIG_SPAPR_TCE_IOMMU
- mm_iommu_init(&mm->context);
+ mm_iommu_init(mm);
#endif
return 0;
}
@@ -160,7 +160,7 @@ static inline void destroy_pagetable_page(struct mm_struct
*mm)
void destroy_context(struct mm_struct *mm)
{
#ifdef CONFIG_SPAPR_TCE_IOMMU
- mm_iommu_cleanup(&mm->context);
+ mm_iommu_cleanup(mm);
#endif
#ifdef CONFIG_PPC_ICSWX
diff --git a/arch/powerpc/mm/mmu_context_iommu.c
b/arch/powerpc/mm/mmu_context_iommu.c
index e0f1c33..4c6db09 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -56,7 +56,7 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
}
pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
- current->pid,
+ current ? current->pid : 0,
incr ? '+' : '-',
npages << PAGE_SHIFT,
mm->locked_vm << PAGE_SHIFT,
@@ -66,12 +66,9 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
return ret;
}
-bool mm_iommu_preregistered(void)
+bool mm_iommu_preregistered(struct mm_struct *mm)
{
- if (!current || !current->mm)
- return false;
-
- return !list_empty(¤t->mm->context.iommu_group_mem_list);
+ return !list_empty(&mm->context.iommu_group_mem_list);
}
EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
@@ -124,19 +121,16 @@ static int mm_iommu_move_page_from_cma(struct page *page)
return 0;
}
-long mm_iommu_get(unsigned long ua, unsigned long entries,
+long mm_iommu_get(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;
long i, j, ret = 0, locked_entries = 0;
struct page *page = NULL;
- if (!current || !current->mm)
- return -ESRCH; /* process exited */
-
mutex_lock(&mem_list_mutex);
- list_for_each_entry_rcu(mem, ¤t->mm->context.iommu_group_mem_list,
+ list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
next) {
if ((mem->ua == ua) && (mem->entries == entries)) {
++mem->used;
@@ -154,7 +148,7 @@ long mm_iommu_get(unsigned long ua, unsigned long entries,
}
- ret = mm_iommu_adjust_locked_vm(current->mm, entries, true);
+ ret = mm_iommu_adjust_locked_vm(mm, entries, true);
if (ret)
goto unlock_exit;
@@ -215,11 +209,11 @@ long mm_iommu_get(unsigned long ua, unsigned long entries,
mem->entries = entries;
*pmem = mem;
- list_add_rcu(&mem->next, ¤t->mm->context.iommu_group_mem_list);
+ list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);
unlock_exit:
if (locked_entries && ret)
- mm_iommu_adjust_locked_vm(current->mm, locked_entries, false);
+ mm_iommu_adjust_locked_vm(mm, locked_entries, false);
mutex_unlock(&mem_list_mutex);
@@ -264,17 +258,13 @@ static void mm_iommu_free(struct rcu_head *head)
static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
{
list_del_rcu(&mem->next);
- mm_iommu_adjust_locked_vm(current->mm, mem->entries, false);
call_rcu(&mem->rcu, mm_iommu_free);
}
-long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem)
+long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
{
long ret = 0;
- if (!current || !current->mm)
- return -ESRCH; /* process exited */
-
mutex_lock(&mem_list_mutex);
if (mem->used == 0) {
@@ -297,6 +287,8 @@ long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem)
/* @mapped became 0 so now mappings are disabled, release the region */
mm_iommu_release(mem);
+ mm_iommu_adjust_locked_vm(mm, mem->entries, false);
+
unlock_exit:
mutex_unlock(&mem_list_mutex);
@@ -304,14 +296,12 @@ long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem)
}
EXPORT_SYMBOL_GPL(mm_iommu_put);
-struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
- unsigned long size)
+struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
+ unsigned long ua, unsigned long size)
{
struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
- list_for_each_entry_rcu(mem,
- ¤t->mm->context.iommu_group_mem_list,
- next) {
+ list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
if ((mem->ua <= ua) &&
(ua + size <= mem->ua +
(mem->entries << PAGE_SHIFT))) {
@@ -324,14 +314,12 @@ struct mm_iommu_table_group_mem_t
*mm_iommu_lookup(unsigned long ua,
}
EXPORT_SYMBOL_GPL(mm_iommu_lookup);
-struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
- unsigned long entries)
+struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
+ unsigned long ua, unsigned long entries)
{
struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
- list_for_each_entry_rcu(mem,
- ¤t->mm->context.iommu_group_mem_list,
- next) {
+ list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
if ((mem->ua == ua) && (mem->entries == entries)) {
ret = mem;
break;
@@ -373,16 +361,17 @@ void mm_iommu_mapped_dec(struct
mm_iommu_table_group_mem_t *mem)
}
EXPORT_SYMBOL_GPL(mm_iommu_mapped_dec);
-void mm_iommu_init(mm_context_t *ctx)
+void mm_iommu_init(struct mm_struct *mm)
{
- INIT_LIST_HEAD_RCU(&ctx->iommu_group_mem_list);
+ INIT_LIST_HEAD_RCU(&mm->context.iommu_group_mem_list);
}
-void mm_iommu_cleanup(mm_context_t *ctx)
+void mm_iommu_cleanup(struct mm_struct *mm)
{
struct mm_iommu_table_group_mem_t *mem, *tmp;
- list_for_each_entry_safe(mem, tmp, &ctx->iommu_group_mem_list, next) {
+ list_for_each_entry_safe(mem, tmp, &mm->context.iommu_group_mem_list,
+ next) {
list_del_rcu(&mem->next);
mm_iommu_do_free(mem);
}
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c
b/drivers/vfio/vfio_iommu_spapr_tce.c
index 80378dd..3d2a65c 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -98,6 +98,7 @@ struct tce_container {
bool enabled;
bool v2;
unsigned long locked_pages;
+ struct mm_struct *mm;
struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
struct list_head group_list;
};
@@ -110,11 +111,11 @@ static long tce_iommu_unregister_pages(struct
tce_container *container,
if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
return -EINVAL;
- mem = mm_iommu_find(vaddr, size >> PAGE_SHIFT);
+ mem = mm_iommu_find(container->mm, vaddr, size >> PAGE_SHIFT);
if (!mem)
return -ENOENT;
- return mm_iommu_put(mem);
+ return mm_iommu_put(container->mm, mem);
}
static long tce_iommu_register_pages(struct tce_container *container,
@@ -128,7 +129,16 @@ static long tce_iommu_register_pages(struct tce_container
*container,
((vaddr + size) < vaddr))
return -EINVAL;
- ret = mm_iommu_get(vaddr, entries, &mem);
+ if (!container->mm) {
+ if (!current->mm)
+ return -ESRCH; /* process exited */
+
+ atomic_inc(¤t->mm->mm_count);
+ BUG_ON(container->mm && (container->mm != current->mm));
+ container->mm = current->mm;
+ }
+
+ ret = mm_iommu_get(container->mm, vaddr, entries, &mem);
if (ret)
return ret;
@@ -354,6 +364,8 @@ static void tce_iommu_release(void *iommu_data)
tce_iommu_free_table(tbl);
}
+ if (container->mm)
+ mmdrop(container->mm);
tce_iommu_disable(container);
mutex_destroy(&container->lock);
@@ -369,13 +381,14 @@ static void tce_iommu_unuse_page(struct tce_container
*container,
put_page(page);
}
-static int tce_iommu_prereg_ua_to_hpa(unsigned long tce, unsigned long size,
+static int tce_iommu_prereg_ua_to_hpa(struct tce_container *container,
+ unsigned long tce, unsigned long size,
unsigned long *phpa, struct mm_iommu_table_group_mem_t **pmem)
{
long ret = 0;
struct mm_iommu_table_group_mem_t *mem;
- mem = mm_iommu_lookup(tce, size);
+ mem = mm_iommu_lookup(container->mm, tce, size);
if (!mem)
return -EINVAL;
@@ -388,18 +401,18 @@ static int tce_iommu_prereg_ua_to_hpa(unsigned long tce,
unsigned long size,
return 0;
}
-static void tce_iommu_unuse_page_v2(struct iommu_table *tbl,
- unsigned long entry)
+static void tce_iommu_unuse_page_v2(struct tce_container *container,
+ struct iommu_table *tbl, unsigned long entry)
{
struct mm_iommu_table_group_mem_t *mem = NULL;
int ret;
unsigned long hpa = 0;
unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
- if (!pua || !current || !current->mm)
+ if (!pua)
return;
- ret = tce_iommu_prereg_ua_to_hpa(*pua, IOMMU_PAGE_SIZE(tbl),
+ ret = tce_iommu_prereg_ua_to_hpa(container, *pua, IOMMU_PAGE_SIZE(tbl),
&hpa, &mem);
if (ret)
pr_debug("%s: tce %lx at #%lx was not cached, ret=%d\n",
@@ -429,7 +442,7 @@ static int tce_iommu_clear(struct tce_container *container,
continue;
if (container->v2) {
- tce_iommu_unuse_page_v2(tbl, entry);
+ tce_iommu_unuse_page_v2(container, tbl, entry);
continue;
}
@@ -514,8 +527,8 @@ static long tce_iommu_build_v2(struct tce_container
*container,
unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl,
entry + i);
- ret = tce_iommu_prereg_ua_to_hpa(tce, IOMMU_PAGE_SIZE(tbl),
- &hpa, &mem);
+ ret = tce_iommu_prereg_ua_to_hpa(container,
+ tce, IOMMU_PAGE_SIZE(tbl), &hpa, &mem);
if (ret)
break;
@@ -536,7 +549,7 @@ static long tce_iommu_build_v2(struct tce_container
*container,
ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
if (ret) {
/* dirtmp cannot be DMA_NONE here */
- tce_iommu_unuse_page_v2(tbl, entry + i);
+ tce_iommu_unuse_page_v2(container, tbl, entry + i);
pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx,
ret=%ld\n",
__func__, entry << tbl->it_page_shift,
tce, ret);
@@ -544,7 +557,7 @@ static long tce_iommu_build_v2(struct tce_container
*container,
}
if (dirtmp != DMA_NONE)
- tce_iommu_unuse_page_v2(tbl, entry + i);
+ tce_iommu_unuse_page_v2(container, tbl, entry + i);
*pua = tce;
--
2.5.0.rc3
