Use an opaque type for pteps and require visitors explicitly dereference
the pointer before using. Protecting page table memory with RCU requires
that KVM dereferences RCU-annotated pointers before using. However, RCU
is not available for use in the nVHE hypervisor and the opaque type can
be conditionally annotated with RCU for the stage-2 MMU.
Call the type a 'pteref' to avoid a naming collision with raw pteps. No
functional change intended.
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
---
arch/arm64/include/asm/kvm_pgtable.h | 9 ++++++++-
arch/arm64/kvm/hyp/pgtable.c | 27 ++++++++++++++-------------
arch/arm64/kvm/mmu.c | 2 +-
3 files changed, 23 insertions(+), 15 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 93b1feeaebab..cbd2851eefc1 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -37,6 +37,13 @@ static inline u64 kvm_get_parange(u64 mmfr0)
typedef u64 kvm_pte_t;
+typedef kvm_pte_t *kvm_pteref_t;
+
+static inline kvm_pte_t *kvm_dereference_pteref(kvm_pteref_t pteref, bool shared)
+{
+ return pteref;
+}
+
#define KVM_PTE_VALID BIT(0)
#define KVM_PTE_ADDR_MASK GENMASK(47, PAGE_SHIFT)
@@ -175,7 +182,7 @@ typedef bool (*kvm_pgtable_force_pte_cb_t)(u64 addr, u64 end,
struct kvm_pgtable {
u32 ia_bits;
u32 start_level;
- kvm_pte_t *pgd;
+ kvm_pteref_t pgd;
struct kvm_pgtable_mm_ops *mm_ops;
/* Stage-2 only */
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 363a5cce7e1a..7511494537e5 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -175,13 +175,14 @@ static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data,
}
static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data,
- struct kvm_pgtable_mm_ops *mm_ops, kvm_pte_t *pgtable, u32 level);
+ struct kvm_pgtable_mm_ops *mm_ops, kvm_pteref_t pgtable, u32 level);
static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
struct kvm_pgtable_mm_ops *mm_ops,
- kvm_pte_t *ptep, u32 level)
+ kvm_pteref_t pteref, u32 level)
{
enum kvm_pgtable_walk_flags flags = data->walker->flags;
+ kvm_pte_t *ptep = kvm_dereference_pteref(pteref, false);
struct kvm_pgtable_visit_ctx ctx = {
.ptep = ptep,
.old = READ_ONCE(*ptep),
@@ -193,7 +194,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
.flags = flags,
};
int ret = 0;
- kvm_pte_t *childp;
+ kvm_pteref_t childp;
bool table = kvm_pte_table(ctx.old, level);
if (table && (ctx.flags & KVM_PGTABLE_WALK_TABLE_PRE))
@@ -214,7 +215,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
goto out;
}
- childp = kvm_pte_follow(ctx.old, mm_ops);
+ childp = (kvm_pteref_t)kvm_pte_follow(ctx.old, mm_ops);
ret = __kvm_pgtable_walk(data, mm_ops, childp, level + 1);
if (ret)
goto out;
@@ -227,7 +228,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
}
static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data,
- struct kvm_pgtable_mm_ops *mm_ops, kvm_pte_t *pgtable, u32 level)
+ struct kvm_pgtable_mm_ops *mm_ops, kvm_pteref_t pgtable, u32 level)
{
u32 idx;
int ret = 0;
@@ -236,12 +237,12 @@ static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data,
return -EINVAL;
for (idx = kvm_pgtable_idx(data, level); idx < PTRS_PER_PTE; ++idx) {
- kvm_pte_t *ptep = &pgtable[idx];
+ kvm_pteref_t pteref = &pgtable[idx];
if (data->addr >= data->end)
break;
- ret = __kvm_pgtable_visit(data, mm_ops, ptep, level);
+ ret = __kvm_pgtable_visit(data, mm_ops, pteref, level);
if (ret)
break;
}
@@ -262,9 +263,9 @@ static int _kvm_pgtable_walk(struct kvm_pgtable *pgt, struct kvm_pgtable_walk_da
return -EINVAL;
for (idx = kvm_pgd_page_idx(pgt, data->addr); data->addr < data->end; ++idx) {
- kvm_pte_t *ptep = &pgt->pgd[idx * PTRS_PER_PTE];
+ kvm_pteref_t pteref = &pgt->pgd[idx * PTRS_PER_PTE];
- ret = __kvm_pgtable_walk(data, pgt->mm_ops, ptep, pgt->start_level);
+ ret = __kvm_pgtable_walk(data, pgt->mm_ops, pteref, pgt->start_level);
if (ret)
break;
}
@@ -507,7 +508,7 @@ int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits,
{
u64 levels = ARM64_HW_PGTABLE_LEVELS(va_bits);
- pgt->pgd = (kvm_pte_t *)mm_ops->zalloc_page(NULL);
+ pgt->pgd = (kvm_pteref_t)mm_ops->zalloc_page(NULL);
if (!pgt->pgd)
return -ENOMEM;
@@ -544,7 +545,7 @@ 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(pgt->pgd);
+ pgt->mm_ops->put_page(kvm_dereference_pteref(pgt->pgd, false));
pgt->pgd = NULL;
}
@@ -1157,7 +1158,7 @@ int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
u32 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0;
pgd_sz = kvm_pgd_pages(ia_bits, start_level) * PAGE_SIZE;
- pgt->pgd = mm_ops->zalloc_pages_exact(pgd_sz);
+ pgt->pgd = (kvm_pteref_t)mm_ops->zalloc_pages_exact(pgd_sz);
if (!pgt->pgd)
return -ENOMEM;
@@ -1200,7 +1201,7 @@ 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(pgt->pgd, pgd_sz);
+ pgt->mm_ops->free_pages_exact(kvm_dereference_pteref(pgt->pgd, false), pgd_sz);
pgt->pgd = NULL;
}
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 60ee3d9f01f8..5e197ae190ef 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -640,7 +640,7 @@ static struct kvm_pgtable_mm_ops kvm_user_mm_ops = {
static int get_user_mapping_size(struct kvm *kvm, u64 addr)
{
struct kvm_pgtable pgt = {
- .pgd = (kvm_pte_t *)kvm->mm->pgd,
+ .pgd = (kvm_pteref_t)kvm->mm->pgd,
.ia_bits = VA_BITS,
.start_level = (KVM_PGTABLE_MAX_LEVELS -
CONFIG_PGTABLE_LEVELS),
--
2.38.1.431.g37b22c650d-goog
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
