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Message-Id: <20231125083400.1399197-3-pbonzini@redhat.com>
Date: Sat, 25 Nov 2023 03:33:58 -0500
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: seanjc@...gle.com, mlevitsk@...hat.com
Subject: [PATCH v2 2/4] KVM: x86/mmu: remove unnecessary "bool shared" argument from iterators
The "bool shared" argument is more or less unnecessary in the
for_each_*_tdp_mmu_root_yield_safe() macros. Many users check for
the lock before calling it; all of them either call small functions
that do the check, or end up calling tdp_mmu_set_spte_atomic() and
tdp_mmu_iter_set_spte(). Add a few assertions to make up for the
lost check in for_each_*_tdp_mmu_root_yield_safe(), but even this
is probably overkill and mostly for documentation reasons.
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 50 +++++++++++++++++++-------------------
1 file changed, 25 insertions(+), 25 deletions(-)
v1->v2: keep lockdep_assert_held()
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 05689c8d45b7..a85b31a3fc44 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -155,23 +155,20 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm,
* If shared is set, this function is operating under the MMU lock in read
* mode.
*/
-#define __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _shared, _only_valid)\
- for (_root = tdp_mmu_next_root(_kvm, NULL, _only_valid); \
- _root; \
- _root = tdp_mmu_next_root(_kvm, _root, _only_valid)) \
- if (kvm_lockdep_assert_mmu_lock_held(_kvm, _shared) && \
- kvm_mmu_page_as_id(_root) != _as_id) { \
+#define __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _only_valid)\
+ for (_root = tdp_mmu_next_root(_kvm, NULL, _only_valid); \
+ ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \
+ _root = tdp_mmu_next_root(_kvm, _root, _only_valid)) \
+ if (kvm_mmu_page_as_id(_root) != _as_id) { \
} else
-#define for_each_valid_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _shared) \
- __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _shared, true)
+#define for_each_valid_tdp_mmu_root_yield_safe(_kvm, _root, _as_id) \
+ __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, true)
-#define for_each_tdp_mmu_root_yield_safe(_kvm, _root, _shared) \
- for (_root = tdp_mmu_next_root(_kvm, NULL, false); \
- _root; \
- _root = tdp_mmu_next_root(_kvm, _root, false)) \
- if (!kvm_lockdep_assert_mmu_lock_held(_kvm, _shared)) { \
- } else
+#define for_each_tdp_mmu_root_yield_safe(_kvm, _root) \
+ for (_root = tdp_mmu_next_root(_kvm, NULL, false); \
+ ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \
+ _root = tdp_mmu_next_root(_kvm, _root, false))
/*
* Iterate over all TDP MMU roots. Requires that mmu_lock be held for write,
@@ -840,7 +837,8 @@ bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush)
{
struct kvm_mmu_page *root;
- for_each_tdp_mmu_root_yield_safe(kvm, root, false)
+ lockdep_assert_held_write(&kvm->mmu_lock);
+ for_each_tdp_mmu_root_yield_safe(kvm, root)
flush = tdp_mmu_zap_leafs(kvm, root, start, end, true, flush);
return flush;
@@ -862,7 +860,8 @@ void kvm_tdp_mmu_zap_all(struct kvm *kvm)
* is being destroyed or the userspace VMM has exited. In both cases,
* KVM_RUN is unreachable, i.e. no vCPUs will ever service the request.
*/
- for_each_tdp_mmu_root_yield_safe(kvm, root, false)
+ lockdep_assert_held_write(&kvm->mmu_lock);
+ for_each_tdp_mmu_root_yield_safe(kvm, root)
tdp_mmu_zap_root(kvm, root, false);
}
@@ -876,7 +875,7 @@ void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm)
read_lock(&kvm->mmu_lock);
- for_each_tdp_mmu_root_yield_safe(kvm, root, true) {
+ for_each_tdp_mmu_root_yield_safe(kvm, root) {
if (!root->tdp_mmu_scheduled_root_to_zap)
continue;
@@ -1133,7 +1132,7 @@ bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range,
{
struct kvm_mmu_page *root;
- __for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, false, false)
+ __for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, false)
flush = tdp_mmu_zap_leafs(kvm, root, range->start, range->end,
range->may_block, flush);
@@ -1322,7 +1323,7 @@ bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm,
lockdep_assert_held_read(&kvm->mmu_lock);
- for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true)
+ for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id)
spte_set |= wrprot_gfn_range(kvm, root, slot->base_gfn,
slot->base_gfn + slot->npages, min_level);
@@ -1354,6 +1355,8 @@ static struct kvm_mmu_page *tdp_mmu_alloc_sp_for_split(struct kvm *kvm,
{
struct kvm_mmu_page *sp;
+ kvm_lockdep_assert_mmu_lock_held(kvm, shared);
+
/*
* Since we are allocating while under the MMU lock we have to be
* careful about GFP flags. Use GFP_NOWAIT to avoid blocking on direct
@@ -1504,8 +1507,7 @@ void kvm_tdp_mmu_try_split_huge_pages(struct kvm *kvm,
int r = 0;
kvm_lockdep_assert_mmu_lock_held(kvm, shared);
-
- for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, shared) {
+ for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id) {
r = tdp_mmu_split_huge_pages_root(kvm, root, start, end, target_level, shared);
if (r) {
kvm_tdp_mmu_put_root(kvm, root);
@@ -1568,8 +1570,7 @@ bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm,
bool spte_set = false;
lockdep_assert_held_read(&kvm->mmu_lock);
-
- for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true)
+ for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id)
spte_set |= clear_dirty_gfn_range(kvm, root, slot->base_gfn,
slot->base_gfn + slot->npages);
@@ -1703,8 +1704,7 @@ void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
struct kvm_mmu_page *root;
lockdep_assert_held_read(&kvm->mmu_lock);
-
- for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true)
+ for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id)
zap_collapsible_spte_range(kvm, root, slot);
}
--
2.39.1
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