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Message-Id: <20221118182222.3932898-2-oliver.upton@linux.dev>
Date: Fri, 18 Nov 2022 18:22:20 +0000
From: Oliver Upton <oliver.upton@...ux.dev>
To: Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Oliver Upton <oliver.upton@...ux.dev>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
kvm@...r.kernel.org, kvmarm@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: [PATCH v4 1/3] 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@...ux.dev>
---
arch/arm64/include/asm/kvm_pgtable.h | 144 ++++++++++++++-------------
arch/arm64/kvm/hyp/pgtable.c | 6 +-
2 files changed, 76 insertions(+), 74 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index a874ce0ce7b5..f23af693e3c5 100644
--- 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 5bca9610d040..b5b91a882836 100644
--- 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;
}
--
2.38.1.584.g0f3c55d4c2-goog
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