[PATCHv15 10/17] iommu/sva: Replace pasid_valid() helper with mm_valid_pasid()

From: Kirill A. Shutemov
Date: Mon Jan 23 2023 - 17:06:12 EST


Kernel has few users of pasid_valid() and all but one checks if the
process has PASID allocated. The helper takes ioasid_t as the input.

Replace the helper with mm_valid_pasid() that takes mm_struct as the
argument. The only call that checks PASID that is not tied to mm_struct
is open-codded now.

This is preparatory patch. It helps avoid ifdeffery: no need to
dereference mm->pasid in generic code to check if the process has PASID.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/kernel/traps.c | 6 +++---
drivers/iommu/iommu-sva.c | 4 ++--
include/linux/ioasid.h | 9 ---------
include/linux/sched/mm.h | 8 +++++++-
4 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index d317dc3d06a3..8b83d8fbce71 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -671,15 +671,15 @@ static bool try_fixup_enqcmd_gp(void)
if (!cpu_feature_enabled(X86_FEATURE_ENQCMD))
return false;

- pasid = current->mm->pasid;
-
/*
* If the mm has not been allocated a
* PASID, the #GP can not be fixed up.
*/
- if (!pasid_valid(pasid))
+ if (!mm_valid_pasid(current->mm))
return false;

+ pasid = current->mm->pasid;
+
/*
* Did this thread already have its PASID activated?
* If so, the #GP must be from something else.
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 24bf9b2b58aa..4ee2929f0d7a 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -34,14 +34,14 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)

mutex_lock(&iommu_sva_lock);
/* Is a PASID already associated with this mm? */
- if (pasid_valid(mm->pasid)) {
+ if (mm_valid_pasid(mm)) {
if (mm->pasid < min || mm->pasid >= max)
ret = -EOVERFLOW;
goto out;
}

pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
- if (!pasid_valid(pasid))
+ if (pasid == INVALID_IOASID)
ret = -ENOMEM;
else
mm_pasid_set(mm, pasid);
diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
index af1c9d62e642..836ae09e92c2 100644
--- a/include/linux/ioasid.h
+++ b/include/linux/ioasid.h
@@ -40,10 +40,6 @@ void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,
int ioasid_register_allocator(struct ioasid_allocator_ops *allocator);
void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
int ioasid_set_data(ioasid_t ioasid, void *data);
-static inline bool pasid_valid(ioasid_t ioasid)
-{
- return ioasid != INVALID_IOASID;
-}

#else /* !CONFIG_IOASID */
static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
@@ -74,10 +70,5 @@ static inline int ioasid_set_data(ioasid_t ioasid, void *data)
return -ENOTSUPP;
}

-static inline bool pasid_valid(ioasid_t ioasid)
-{
- return false;
-}
-
#endif /* CONFIG_IOASID */
#endif /* __LINUX_IOASID_H */
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 2a243616f222..b69fe7e8c0ac 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -457,6 +457,11 @@ static inline void mm_pasid_init(struct mm_struct *mm)
mm->pasid = INVALID_IOASID;
}

+static inline bool mm_valid_pasid(struct mm_struct *mm)
+{
+ return mm->pasid != INVALID_IOASID;
+}
+
/* Associate a PASID with an mm_struct: */
static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid)
{
@@ -465,13 +470,14 @@ static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid)

static inline void mm_pasid_drop(struct mm_struct *mm)
{
- if (pasid_valid(mm->pasid)) {
+ if (mm_valid_pasid(mm)) {
ioasid_free(mm->pasid);
mm->pasid = INVALID_IOASID;
}
}
#else
static inline void mm_pasid_init(struct mm_struct *mm) {}
+static inline bool mm_valid_pasid(struct mm_struct *mm) { return false; }
static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid) {}
static inline void mm_pasid_drop(struct mm_struct *mm) {}
#endif
--
2.39.1