linux-kernel - [PATCHv12 10/16] iommu/sva: Replace pasid_valid() helper with mm_valid

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Date:   Wed,  9 Nov 2022 19:51:34 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, Kostya Serebryany <kcc@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Taras Madan <tarasmadan@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        "H . J . Lu" <hjl.tools@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Bharata B Rao <bharata@....com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Ashok Raj <ashok.raj@...el.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv12 10/16] iommu/sva: Replace pasid_valid() helper with mm_valid_pasid()

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@...ux.intel.com>
---
 arch/x86/kernel/traps.c       | 6 +++---
 drivers/iommu/iommu-sva-lib.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 178015a820f0..3bdc37ae7d1c 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -664,15 +664,15 @@ 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-lib.c b/drivers/iommu/iommu-sva-lib.c
index 106506143896..27be6b81e0b5 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -33,14 +33,14 @@ 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
-- 
2.38.0