A subsequent change to KVM will parallize modifications to the stage-2
page tables. The various page table walkers read the ptep multiple
times, which could lead to a visitor seeing multiple values during the
visit.
Pass through the observed pte to the visitor callbacks. Promote reads of
the ptep to a full READ_ONCE(), which will matter more when we start
tweaking ptes atomically. Note that a pointer to the old pte is given to
visitors, as parallel visitors will need to steer the page table
traversal as they adjust the page tables.
Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_pgtable.h | 2 +-
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 7 +-
arch/arm64/kvm/hyp/nvhe/setup.c | 9 +-
arch/arm64/kvm/hyp/pgtable.c | 113 +++++++++++++-------------
4 files changed, 63 insertions(+), 68 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 9f339dffbc1a..ea818a5f7408 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -192,7 +192,7 @@ enum kvm_pgtable_walk_flags {
};
typedef int (*kvm_pgtable_visitor_fn_t)(u64 addr, u64 end, u32 level,
- kvm_pte_t *ptep,
+ kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag,
void * const arg);
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 78edf077fa3b..601a586581d8 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -422,17 +422,16 @@ struct check_walk_data {
};
static int __check_page_state_visitor(u64 addr, u64 end, u32 level,
- kvm_pte_t *ptep,
+ kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag,
void * const arg)
{
struct check_walk_data *d = arg;
- kvm_pte_t pte = *ptep;
- if (kvm_pte_valid(pte) && !addr_is_memory(kvm_pte_to_phys(pte)))
+ if (kvm_pte_valid(*old) && !addr_is_memory(kvm_pte_to_phys(*old)))
return -EINVAL;
- return d->get_page_state(pte) == d->desired ? 0 : -EPERM;
+ return d->get_page_state(*old) == d->desired ? 0 : -EPERM;
}
static int check_page_state_range(struct kvm_pgtable *pgt, u64 addr, u64 size,
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 27af337f9fea..ecab7a4049d6 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -162,17 +162,16 @@ static void hpool_put_page(void *addr)
}
static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level,
- kvm_pte_t *ptep,
+ kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag,
void * const arg)
{
struct kvm_pgtable_mm_ops *mm_ops = arg;
enum kvm_pgtable_prot prot;
enum pkvm_page_state state;
- kvm_pte_t pte = *ptep;
phys_addr_t phys;
- if (!kvm_pte_valid(pte))
+ if (!kvm_pte_valid(*old))
return 0;
/*
@@ -187,7 +186,7 @@ static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level,
if (level != (KVM_PGTABLE_MAX_LEVELS - 1))
return -EINVAL;
- phys = kvm_pte_to_phys(pte);
+ phys = kvm_pte_to_phys(*old);
if (!addr_is_memory(phys))
return -EINVAL;
@@ -195,7 +194,7 @@ static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level,
* Adjust the host stage-2 mappings to match the ownership attributes
* configured in the hypervisor stage-1.
*/
- state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(pte));
+ state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(*old));
switch (state) {
case PKVM_PAGE_OWNED:
return host_stage2_set_owner_locked(phys, PAGE_SIZE, pkvm_hyp_id);
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index e1506da3e2fb..ad911cd44425 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -178,11 +178,11 @@ static u8 kvm_invalid_pte_owner(kvm_pte_t pte)
}
static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr,
- u32 level, kvm_pte_t *ptep,
+ u32 level, kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag)
{
struct kvm_pgtable_walker *walker = data->walker;
- return walker->cb(addr, data->end, level, ptep, flag, walker->arg);
+ return walker->cb(addr, data->end, level, ptep, old, flag, walker->arg);
}
static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data,
@@ -193,17 +193,17 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
{
int ret = 0;
u64 addr = data->addr;
- kvm_pte_t *childp, pte = *ptep;
+ kvm_pte_t *childp, pte = READ_ONCE(*ptep);
bool table = kvm_pte_table(pte, level);
enum kvm_pgtable_walk_flags flags = data->walker->flags;
if (table && (flags & KVM_PGTABLE_WALK_TABLE_PRE)) {
- ret = kvm_pgtable_visitor_cb(data, addr, level, ptep,
+ ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, &pte,
KVM_PGTABLE_WALK_TABLE_PRE);
}
if (!table && (flags & KVM_PGTABLE_WALK_LEAF)) {
- ret = kvm_pgtable_visitor_cb(data, addr, level, ptep,
+ ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, &pte,
KVM_PGTABLE_WALK_LEAF);
pte = *ptep;
table = kvm_pte_table(pte, level);
@@ -224,7 +224,7 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data,
goto out;
if (flags & KVM_PGTABLE_WALK_TABLE_POST) {
- ret = kvm_pgtable_visitor_cb(data, addr, level, ptep,
+ ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, &pte,
KVM_PGTABLE_WALK_TABLE_POST);
}
@@ -297,12 +297,12 @@ struct leaf_walk_data {
u32 level;
};
-static int leaf_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+static int leaf_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag, void * const arg)
{
struct leaf_walk_data *data = arg;
- data->pte = *ptep;
+ data->pte = *old;
data->level = level;
return 0;
@@ -388,10 +388,10 @@ enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte)
return prot;
}
-static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level,
- kvm_pte_t *ptep, struct hyp_map_data *data)
+static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+ kvm_pte_t old, struct hyp_map_data *data)
{
- kvm_pte_t new, old = *ptep;
+ kvm_pte_t new;
u64 granule = kvm_granule_size(level), phys = data->phys;
if (!kvm_block_mapping_supported(addr, end, phys, level))
@@ -410,14 +410,14 @@ static bool hyp_map_walker_try_leaf(u64 addr, u64 end, u32 level,
return true;
}
-static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag, void * const arg)
{
kvm_pte_t *childp;
struct hyp_map_data *data = arg;
struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
- if (hyp_map_walker_try_leaf(addr, end, level, ptep, arg))
+ if (hyp_map_walker_try_leaf(addr, end, level, ptep, *old, arg))
return 0;
if (WARN_ON(level == KVM_PGTABLE_MAX_LEVELS - 1))
@@ -461,19 +461,19 @@ struct hyp_unmap_data {
struct kvm_pgtable_mm_ops *mm_ops;
};
-static int hyp_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+static int hyp_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag, void * const arg)
{
- kvm_pte_t pte = *ptep, *childp = NULL;
+ kvm_pte_t *childp = NULL;
u64 granule = kvm_granule_size(level);
struct hyp_unmap_data *data = arg;
struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
- if (!kvm_pte_valid(pte))
+ if (!kvm_pte_valid(*old))
return -EINVAL;
- if (kvm_pte_table(pte, level)) {
- childp = kvm_pte_follow(pte, mm_ops);
+ if (kvm_pte_table(*old, level)) {
+ childp = kvm_pte_follow(*old, mm_ops);
if (mm_ops->page_count(childp) != 1)
return 0;
@@ -537,19 +537,18 @@ int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits,
return 0;
}
-static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, kvm_pte_t *old,
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))
+ if (!kvm_pte_valid(*old))
return 0;
mm_ops->put_page(ptep);
- if (kvm_pte_table(pte, level))
- mm_ops->put_page(kvm_pte_follow(pte, mm_ops));
+ if (kvm_pte_table(*old, level))
+ mm_ops->put_page(kvm_pte_follow(*old, mm_ops));
return 0;
}
@@ -723,10 +722,10 @@ static bool stage2_leaf_mapping_allowed(u64 addr, u64 end, u32 level,
}
static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
- kvm_pte_t *ptep,
+ kvm_pte_t *ptep, kvm_pte_t old,
struct stage2_map_data *data)
{
- kvm_pte_t new, old = *ptep;
+ kvm_pte_t new;
u64 granule = kvm_granule_size(level), phys = data->phys;
struct kvm_pgtable *pgt = data->mmu->pgt;
struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
@@ -769,7 +768,7 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
}
static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
- kvm_pte_t *ptep,
+ kvm_pte_t *ptep, kvm_pte_t *old,
struct stage2_map_data *data)
{
if (data->anchor)
@@ -778,7 +777,7 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
if (!stage2_leaf_mapping_allowed(addr, end, level, data))
return 0;
- data->childp = kvm_pte_follow(*ptep, data->mm_ops);
+ data->childp = kvm_pte_follow(*old, data->mm_ops);
kvm_clear_pte(ptep);
/*
@@ -792,20 +791,20 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
}
static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
- struct stage2_map_data *data)
+ kvm_pte_t *old, struct stage2_map_data *data)
{
struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
- kvm_pte_t *childp, pte = *ptep;
+ kvm_pte_t *childp;
int ret;
if (data->anchor) {
- if (stage2_pte_is_counted(pte))
+ if (stage2_pte_is_counted(*old))
mm_ops->put_page(ptep);
return 0;
}
- ret = stage2_map_walker_try_leaf(addr, end, level, ptep, data);
+ ret = stage2_map_walker_try_leaf(addr, end, level, ptep, *old, data);
if (ret != -E2BIG)
return ret;
@@ -824,7 +823,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
* a table. Accesses beyond 'end' that fall within the new table
* will be mapped lazily.
*/
- if (stage2_pte_is_counted(pte))
+ if (stage2_pte_is_counted(*old))
stage2_put_pte(ptep, data->mmu, addr, level, mm_ops);
kvm_set_table_pte(ptep, childp, mm_ops);
@@ -834,7 +833,7 @@ static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
}
static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
- kvm_pte_t *ptep,
+ kvm_pte_t *ptep, kvm_pte_t *old,
struct stage2_map_data *data)
{
struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
@@ -848,9 +847,9 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
childp = data->childp;
data->anchor = NULL;
data->childp = NULL;
- ret = stage2_map_walk_leaf(addr, end, level, ptep, data);
+ ret = stage2_map_walk_leaf(addr, end, level, ptep, old, data);
} else {
- childp = kvm_pte_follow(*ptep, mm_ops);
+ childp = kvm_pte_follow(*old, mm_ops);
}
mm_ops->put_page(childp);
@@ -878,18 +877,18 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
* the page-table, installing the block entry when it revisits the anchor
* pointer and clearing the anchor to NULL.
*/
-static int stage2_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+static int stage2_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, kvm_pte_t *old,
enum kvm_pgtable_walk_flags flag, void * const arg)
{
struct stage2_map_data *data = arg;
switch (flag) {
case KVM_PGTABLE_WALK_TABLE_PRE:
- return stage2_map_walk_table_pre(addr, end, level, ptep, data);
+ return stage2_map_walk_table_pre(addr, end, level, ptep, old, data);
case KVM_PGTABLE_WALK_LEAF:
- return stage2_map_walk_leaf(addr, end, level, ptep, data);
+ return stage2_map_walk_leaf(addr, end, level, ptep, old, data);
case KVM_PGTABLE_WALK_TABLE_POST:
- return stage2_map_walk_table_post(addr, end, level, ptep, data);
+ return stage2_map_walk_table_post(addr, end, level, ptep, old, data);
}
return -EINVAL;
@@ -955,29 +954,29 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
}
static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
- enum kvm_pgtable_walk_flags flag,
+ kvm_pte_t *old, enum kvm_pgtable_walk_flags flag,
void * const arg)
{
struct kvm_pgtable *pgt = arg;
struct kvm_s2_mmu *mmu = pgt->mmu;
struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
- kvm_pte_t pte = *ptep, *childp = NULL;
+ kvm_pte_t *childp = NULL;
bool need_flush = false;
- if (!kvm_pte_valid(pte)) {
- if (stage2_pte_is_counted(pte)) {
+ if (!kvm_pte_valid(*old)) {
+ if (stage2_pte_is_counted(*old)) {
kvm_clear_pte(ptep);
mm_ops->put_page(ptep);
}
return 0;
}
- if (kvm_pte_table(pte, level)) {
- childp = kvm_pte_follow(pte, mm_ops);
+ if (kvm_pte_table(*old, level)) {
+ childp = kvm_pte_follow(*old, mm_ops);
if (mm_ops->page_count(childp) != 1)
return 0;
- } else if (stage2_pte_cacheable(pgt, pte)) {
+ } else if (stage2_pte_cacheable(pgt, *old)) {
need_flush = !stage2_has_fwb(pgt);
}
@@ -989,7 +988,7 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
stage2_put_pte(ptep, mmu, addr, level, mm_ops);
if (need_flush && mm_ops->dcache_clean_inval_poc)
- mm_ops->dcache_clean_inval_poc(kvm_pte_follow(pte, mm_ops),
+ mm_ops->dcache_clean_inval_poc(kvm_pte_follow(*old, mm_ops),
kvm_granule_size(level));
if (childp)
@@ -1018,10 +1017,10 @@ struct stage2_attr_data {
};
static int stage2_attr_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
- enum kvm_pgtable_walk_flags flag,
+ kvm_pte_t *old, enum kvm_pgtable_walk_flags flag,
void * const arg)
{
- kvm_pte_t pte = *ptep;
+ kvm_pte_t pte = *old;
struct stage2_attr_data *data = arg;
struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops;
@@ -1146,18 +1145,17 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr,
}
static int stage2_flush_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
- enum kvm_pgtable_walk_flags flag,
+ kvm_pte_t *old, enum kvm_pgtable_walk_flags flag,
void * const arg)
{
struct kvm_pgtable *pgt = arg;
struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
- kvm_pte_t pte = *ptep;
- if (!kvm_pte_valid(pte) || !stage2_pte_cacheable(pgt, pte))
+ if (!kvm_pte_valid(*old) || !stage2_pte_cacheable(pgt, *old))
return 0;
if (mm_ops->dcache_clean_inval_poc)
- mm_ops->dcache_clean_inval_poc(kvm_pte_follow(pte, mm_ops),
+ mm_ops->dcache_clean_inval_poc(kvm_pte_follow(*old, mm_ops),
kvm_granule_size(level));
return 0;
}
@@ -1206,19 +1204,18 @@ int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
}
static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
- enum kvm_pgtable_walk_flags flag,
+ kvm_pte_t *old, enum kvm_pgtable_walk_flags flag,
void * const arg)
{
struct kvm_pgtable_mm_ops *mm_ops = arg;
- kvm_pte_t pte = *ptep;
- if (!stage2_pte_is_counted(pte))
+ if (!stage2_pte_is_counted(*old))
return 0;
mm_ops->put_page(ptep);
- if (kvm_pte_table(pte, level))
- mm_ops->put_page(kvm_pte_follow(pte, mm_ops));
+ if (kvm_pte_table(*old, level))
+ mm_ops->put_page(kvm_pte_follow(*old, mm_ops));
return 0;
}
--
2.36.0.rc0.470.gd361397f0d-goog
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