[PATCH v3 11/15] KVM: arm64: Split init and set for table PTE

Oliver Upton
2022-10-27T22:22:42Z

Create a helper to initialize a table and directly call
smp_store_release() to install it (for now). Prepare for a subsequent
change that generalizes PTE writes with a helper.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/kvm/hyp/pgtable.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 7c0dd58544b0..4c579b3beabf 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -136,16 +136,13 @@ static void kvm_clear_pte(kvm_pte_t *ptep)
WRITE_ONCE(*ptep, 0);
}

-static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp,
- struct kvm_pgtable_mm_ops *mm_ops)
+static kvm_pte_t kvm_init_table_pte(kvm_pte_t *childp, struct kvm_pgtable_mm_ops *mm_ops)
{
- kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp));
+ kvm_pte_t pte = kvm_phys_to_pte(mm_ops->virt_to_phys(childp));

pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE);
pte |= KVM_PTE_VALID;
-
- WARN_ON(kvm_pte_valid(old));
- smp_store_release(ptep, pte);
+ return pte;
}

static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level)
@@ -413,7 +410,7 @@ static bool hyp_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx,
static int hyp_map_walker(const struct kvm_pgtable_visit_ctx *ctx,
enum kvm_pgtable_walk_flags visit)
{
- kvm_pte_t *childp;
+ kvm_pte_t *childp, new;
struct hyp_map_data *data = ctx->arg;
struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops;

@@ -427,8 +424,10 @@ static int hyp_map_walker(const struct kvm_pgtable_visit_ctx *ctx,
if (!childp)
return -ENOMEM;

- kvm_set_table_pte(ctx->ptep, childp, mm_ops);
+ new = kvm_init_table_pte(childp, mm_ops);
mm_ops->get_page(ctx->ptep);
+ smp_store_release(ctx->ptep, new);
+
return 0;
}

@@ -821,8 +820,9 @@ static int stage2_map_walk_leaf(const struct kvm_pgtable_visit_ctx *ctx,
if (stage2_pte_is_counted(ctx->old))
stage2_put_pte(ctx, data->mmu, mm_ops);

- kvm_set_table_pte(ctx->ptep, childp, mm_ops);
+ new = kvm_init_table_pte(childp, mm_ops);
mm_ops->get_page(ctx->ptep);
+ smp_store_release(ctx->ptep, new);

return 0;
}
--
2.38.1.273.g43a17bfeac-goog