KVM: arm64: Don't pass kvm_pgtable through kvm_pgtable_walk_data

In order to tear down page tables from outside the context of
kvm_pgtable (such as an RCU callback), stop passing a pointer through
kvm_pgtable_walk_data.

No functional change intended.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221107215644.1895162-5-oliver.upton@linux.dev

arch/arm64/kvm/hyp/pgtable.c

@@ -50,7 +50,6 @@
 #define KVM_MAX_OWNER_ID		1
 
 struct kvm_pgtable_walk_data {
-	struct kvm_pgtable		*pgt;
 	struct kvm_pgtable_walker	*walker;
 
 	u64				addr;
@@ -88,7 +87,7 @@ static u32 kvm_pgtable_idx(struct kvm_pgtable_walk_data *data, u32 level)
 	return (data->addr >> shift) & mask;
 }
 
-static u32 __kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr)
+static u32 kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr)
 {
 	u64 shift = kvm_granule_shift(pgt->start_level - 1); /* May underflow */
 	u64 mask = BIT(pgt->ia_bits) - 1;
@@ -96,11 +95,6 @@ static u32 __kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr)
 	return (addr & mask) >> shift;
 }
 
-static u32 kvm_pgd_page_idx(struct kvm_pgtable_walk_data *data)
-{
-	return __kvm_pgd_page_idx(data->pgt, data->addr);
-}
-
 static u32 kvm_pgd_pages(u32 ia_bits, u32 start_level)
 {
 	struct kvm_pgtable pgt = {
@@ -108,7 +102,7 @@ static u32 kvm_pgd_pages(u32 ia_bits, u32 start_level)
 		.start_level	= start_level,
 	};
 
-	return __kvm_pgd_page_idx(&pgt, -1ULL) + 1;
+	return kvm_pgd_page_idx(&pgt, -1ULL) + 1;
 }
 
 static bool kvm_pte_table(kvm_pte_t pte, u32 level)
@@ -255,11 +249,10 @@ static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data,
 	return ret;
 }
 
-static int _kvm_pgtable_walk(struct kvm_pgtable_walk_data *data)
+static int _kvm_pgtable_walk(struct kvm_pgtable *pgt, struct kvm_pgtable_walk_data *data)
 {
 	u32 idx;
 	int ret = 0;
-	struct kvm_pgtable *pgt = data->pgt;
 	u64 limit = BIT(pgt->ia_bits);
 
 	if (data->addr > limit || data->end > limit)
@@ -268,7 +261,7 @@ static int _kvm_pgtable_walk(struct kvm_pgtable_walk_data *data)
 	if (!pgt->pgd)
 		return -EINVAL;
 
-	for (idx = kvm_pgd_page_idx(data); data->addr < data->end; ++idx) {
+	for (idx = kvm_pgd_page_idx(pgt, data->addr); data->addr < data->end; ++idx) {
 		kvm_pte_t *ptep = &pgt->pgd[idx * PTRS_PER_PTE];
 
 		ret = __kvm_pgtable_walk(data, pgt->mm_ops, ptep, pgt->start_level);
@@ -283,13 +276,12 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		     struct kvm_pgtable_walker *walker)
 {
 	struct kvm_pgtable_walk_data walk_data = {
-		.pgt	= pgt,
 		.addr	= ALIGN_DOWN(addr, PAGE_SIZE),
 		.end	= PAGE_ALIGN(walk_data.addr + size),
 		.walker	= walker,
 	};
 
-	return _kvm_pgtable_walk(&walk_data);
+	return _kvm_pgtable_walk(pgt, &walk_data);
 }
 
 struct leaf_walk_data {