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KVM: x86/mmu: remove unnecessary "bool shared" argument from iterators

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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@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-3-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Paolo Bonzini 2023-11-25 03:33:58 -05:00 committed by Sean Christopherson
parent 5f3c8c9187
commit 484dd27c06
1 changed files with 23 additions and 25 deletions
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48
arch/x86/kvm/mmu/tdp_mmu.c
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@ -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 +1321,7 @@ 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 +1353,8 @@ 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 +1505,7 @@ 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);
@ -1569,8 +1569,7 @@ 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);
@ -1704,8 +1703,7 @@ 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);
}