[PATCH v2 03/15] KVM: arm64: Refcount hyp stage-1 pgtable pages
From: Quentin Perret <hidden>
Date: 2021-10-19 12:13:21
Also in:
kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
To prepare the ground for allowing hyp stage-1 mappings to be removed at
run-time, update the KVM page-table code to maintain a correct refcount
using the ->{get,put}_page() function callbacks.
Signed-off-by: Quentin Perret <redacted>
---
arch/arm64/kvm/hyp/pgtable.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index f8ceebe4982e..768a58835153 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c@@ -408,8 +408,10 @@ static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, return false; new = kvm_init_valid_leaf_pte(phys, data->attr, level); - if (hyp_pte_needs_update(old, new)) + if (hyp_pte_needs_update(old, new)) { smp_store_release(ptep, new); + data->mm_ops->get_page(ptep); + } data->phys += granule; return true;
@@ -433,6 +435,7 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, return -ENOMEM; kvm_set_table_pte(ptep, childp, mm_ops); + mm_ops->get_page(ptep); return 0; }
@@ -482,8 +485,16 @@ static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, enum kvm_pgtable_walk_flags flag, void * const arg) { struct kvm_pgtable_mm_ops *mm_ops = arg; + kvm_pte_t pte = *ptep; + + if (!kvm_pte_valid(pte)) + return 0; + + mm_ops->put_page(ptep); + + if (kvm_pte_table(pte, level)) + mm_ops->put_page(kvm_pte_follow(pte, mm_ops)); - mm_ops->put_page((void *)kvm_pte_follow(*ptep, mm_ops)); return 0; }
@@ -491,7 +502,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt) { struct kvm_pgtable_walker walker = { .cb = hyp_free_walker, - .flags = KVM_PGTABLE_WALK_TABLE_POST, + .flags = KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST, .arg = pgt->mm_ops, };
--
2.33.0.1079.g6e70778dc9-goog
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