KVM: arm64: Take a pointer to walker data in kvm_dereference_pteref()

Rather than passing through the state of the KVM_PGTABLE_WALK_SHARED
flag, just take a pointer to the whole walker structure instead. Move
around struct kvm_pgtable and the RCU indirection such that the
associated ifdeffery remains in one place while ensuring the walker +
flags definitions precede their use.

No functional change intended.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221118182222.3932898-2-oliver.upton@linux.dev

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index a874ce0ce7b51e0978fe0e9f9038079f96df731d..f23af693e3c5241955f9430e546ec2907ea698e5 100644 (file)
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -37,54 +37,6 @@ static inline u64 kvm_get_parange(u64 mmfr0)
 
 typedef u64 kvm_pte_t;
 
-/*
- * RCU cannot be used in a non-kernel context such as the hyp. As such, page
- * table walkers used in hyp do not call into RCU and instead use other
- * synchronization mechanisms (such as a spinlock).
- */
-#if defined(__KVM_NVHE_HYPERVISOR__) || defined(__KVM_VHE_HYPERVISOR__)
-
-typedef kvm_pte_t *kvm_pteref_t;
-
-static inline kvm_pte_t *kvm_dereference_pteref(kvm_pteref_t pteref, bool shared)
-{
-       return pteref;
-}
-
-static inline void kvm_pgtable_walk_begin(void) {}
-static inline void kvm_pgtable_walk_end(void) {}
-
-static inline bool kvm_pgtable_walk_lock_held(void)
-{
-       return true;
-}
-
-#else
-
-typedef kvm_pte_t __rcu *kvm_pteref_t;
-
-static inline kvm_pte_t *kvm_dereference_pteref(kvm_pteref_t pteref, bool shared)
-{
-       return rcu_dereference_check(pteref, !shared);
-}
-
-static inline void kvm_pgtable_walk_begin(void)
-{
-       rcu_read_lock();
-}
-
-static inline void kvm_pgtable_walk_end(void)
-{
-       rcu_read_unlock();
-}
-
-static inline bool kvm_pgtable_walk_lock_held(void)
-{
-       return rcu_read_lock_held();
-}
-
-#endif
-
 #define KVM_PTE_VALID                  BIT(0)
 
 #define KVM_PTE_ADDR_MASK              GENMASK(47, PAGE_SHIFT)
@@ -212,29 +164,6 @@ enum kvm_pgtable_prot {
 typedef bool (*kvm_pgtable_force_pte_cb_t)(u64 addr, u64 end,
                                           enum kvm_pgtable_prot prot);
 
-/**
- * struct kvm_pgtable - KVM page-table.
- * @ia_bits:           Maximum input address size, in bits.
- * @start_level:       Level at which the page-table walk starts.
- * @pgd:               Pointer to the first top-level entry of the page-table.
- * @mm_ops:            Memory management callbacks.
- * @mmu:               Stage-2 KVM MMU struct. Unused for stage-1 page-tables.
- * @flags:             Stage-2 page-table flags.
- * @force_pte_cb:      Function that returns true if page level mappings must
- *                     be used instead of block mappings.
- */
-struct kvm_pgtable {
-       u32                                     ia_bits;
-       u32                                     start_level;
-       kvm_pteref_t                            pgd;
-       struct kvm_pgtable_mm_ops               *mm_ops;
-
-       /* Stage-2 only */
-       struct kvm_s2_mmu                       *mmu;
-       enum kvm_pgtable_stage2_flags           flags;
-       kvm_pgtable_force_pte_cb_t              force_pte_cb;
-};
-
 /**
  * enum kvm_pgtable_walk_flags - Flags to control a depth-first page-table walk.
  * @KVM_PGTABLE_WALK_LEAF:             Visit leaf entries, including invalid
@@ -285,6 +214,79 @@ struct kvm_pgtable_walker {
        const enum kvm_pgtable_walk_flags       flags;
 };
 
+/*
+ * RCU cannot be used in a non-kernel context such as the hyp. As such, page
+ * table walkers used in hyp do not call into RCU and instead use other
+ * synchronization mechanisms (such as a spinlock).
+ */
+#if defined(__KVM_NVHE_HYPERVISOR__) || defined(__KVM_VHE_HYPERVISOR__)
+
+typedef kvm_pte_t *kvm_pteref_t;
+
+static inline kvm_pte_t *kvm_dereference_pteref(struct kvm_pgtable_walker *walker,
+                                               kvm_pteref_t pteref)
+{
+       return pteref;
+}
+
+static inline void kvm_pgtable_walk_begin(void) {}
+static inline void kvm_pgtable_walk_end(void) {}
+
+static inline bool kvm_pgtable_walk_lock_held(void)
+{
+       return true;
+}
+
+#else
+
+typedef kvm_pte_t __rcu *kvm_pteref_t;
+
+static inline kvm_pte_t *kvm_dereference_pteref(struct kvm_pgtable_walker *walker,
+                                               kvm_pteref_t pteref)
+{
+       return rcu_dereference_check(pteref, !(walker->flags & KVM_PGTABLE_WALK_SHARED));
+}
+
+static inline void kvm_pgtable_walk_begin(void)
+{
+       rcu_read_lock();
+}
+
+static inline void kvm_pgtable_walk_end(void)
+{
+       rcu_read_unlock();
+}
+
+static inline bool kvm_pgtable_walk_lock_held(void)
+{
+       return rcu_read_lock_held();
+}
+
+#endif
+
+/**
+ * struct kvm_pgtable - KVM page-table.
+ * @ia_bits:           Maximum input address size, in bits.
+ * @start_level:       Level at which the page-table walk starts.
+ * @pgd:               Pointer to the first top-level entry of the page-table.
+ * @mm_ops:            Memory management callbacks.
+ * @mmu:               Stage-2 KVM MMU struct. Unused for stage-1 page-tables.
+ * @flags:             Stage-2 page-table flags.
+ * @force_pte_cb:      Function that returns true if page level mappings must
+ *                     be used instead of block mappings.
+ */
+struct kvm_pgtable {
+       u32                                     ia_bits;
+       u32                                     start_level;
+       kvm_pteref_t                            pgd;
+       struct kvm_pgtable_mm_ops               *mm_ops;
+
+       /* Stage-2 only */
+       struct kvm_s2_mmu                       *mmu;
+       enum kvm_pgtable_stage2_flags           flags;
+       kvm_pgtable_force_pte_cb_t              force_pte_cb;
+};
+
 /**
  * kvm_pgtable_hyp_init() - Initialise a hypervisor stage-1 page-table.
  * @pgt:       Uninitialised page-table structure to initialise.

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 5bca9610d040d99ec01617b625fd9ea1f159d256..b5b91a88283653166456b64de78799d88ae0b228 100644 (file)
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -188,7 +188,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
                                      kvm_pteref_t pteref, u32 level)
 {
        enum kvm_pgtable_walk_flags flags = data->walker->flags;
-       kvm_pte_t *ptep = kvm_dereference_pteref(pteref, flags & KVM_PGTABLE_WALK_SHARED);
+       kvm_pte_t *ptep = kvm_dereference_pteref(data->walker, pteref);
        struct kvm_pgtable_visit_ctx ctx = {
                .ptep   = ptep,
                .old    = READ_ONCE(*ptep),
@@ -558,7 +558,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
        };
 
        WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
-       pgt->mm_ops->put_page(kvm_dereference_pteref(pgt->pgd, false));
+       pgt->mm_ops->put_page(kvm_dereference_pteref(&walker, pgt->pgd));
        pgt->pgd = NULL;
 }
 
@@ -1241,7 +1241,7 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
 
        WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
        pgd_sz = kvm_pgd_pages(pgt->ia_bits, pgt->start_level) * PAGE_SIZE;
-       pgt->mm_ops->free_pages_exact(kvm_dereference_pteref(pgt->pgd, false), pgd_sz);
+       pgt->mm_ops->free_pages_exact(kvm_dereference_pteref(&walker, pgt->pgd), pgd_sz);
        pgt->pgd = NULL;
 }