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KVM: arm64: Refcount hyp stage-1 pgtable pages

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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 <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-3-qperret@google.com
This commit is contained in:
Quentin Perret 2021-12-15 16:12:19 +00:00 committed by Marc Zyngier
parent 1fac3cfb9c
commit 2ea2ff91e8
1 changed files with 20 additions and 21 deletions
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41
arch/arm64/kvm/hyp/pgtable.c
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@ -383,21 +383,6 @@ enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte)
return prot;
}
static bool hyp_pte_needs_update(kvm_pte_t old, kvm_pte_t new)
{
/*
* Tolerate KVM recreating the exact same mapping, or changing software
* bits if the existing mapping was valid.
*/
if (old == new)
return false;
if (!kvm_pte_valid(old))
return true;
return !WARN_ON((old ^ new) & ~KVM_PTE_LEAF_ATTR_HI_SW);
}
static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level,
kvm_pte_t *ptep, struct hyp_map_data *data)
{
@ -407,11 +392,16 @@ static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level,
if (!kvm_block_mapping_supported(addr, end, phys, level))
return false;
new = kvm_init_valid_leaf_pte(phys, data->attr, level);
if (hyp_pte_needs_update(old, new))
smp_store_release(ptep, new);
data->phys += granule;
new = kvm_init_valid_leaf_pte(phys, data->attr, level);
if (old == new)
return true;
if (!kvm_pte_valid(old))
data->mm_ops->get_page(ptep);
else if (WARN_ON((old ^ new) & ~KVM_PTE_LEAF_ATTR_HI_SW))
return false;
smp_store_release(ptep, new);
return true;
}
@ -433,6 +423,7 @@ 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 +473,16 @@ 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 +490,7 @@ 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,
};