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KVM: s390: Use try_cmpxchg() instead of cmpxchg() loops

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Convert all cmpxchg() loops to try_cmpxchg() loops. With gcc 14 and the
usage of flag output operands in try_cmpxchg() this allows the compiler to
generate slightly better code.

Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20241126102515.3178914-2-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Heiko Carstens
2024-11-26 11:25:13 +01:00
parent 7726b55b5d
commit 5618c53d96
4 changed files with 18 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
arch/s390/kvm/gaccess.c
View File

@@ -129,8 +129,8 @@ static void ipte_lock_simple(struct kvm *kvm)
retry:
read_lock(&kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(kvm);
old = READ_ONCE(*ic);
do {
old = READ_ONCE(*ic);
if (old.k) {
read_unlock(&kvm->arch.sca_lock);
cond_resched();
@@ -138,7 +138,7 @@ static void ipte_lock_simple(struct kvm *kvm)
}
new = old;
new.k = 1;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
} while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
out:
mutex_unlock(&kvm->arch.ipte_mutex);
@@ -154,11 +154,11 @@ static void ipte_unlock_simple(struct kvm *kvm)
goto out;
read_lock(&kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(kvm);
old = READ_ONCE(*ic);
do {
old = READ_ONCE(*ic);
new = old;
new.k = 0;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
} while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
wake_up(&kvm->arch.ipte_wq);
out:
@@ -172,8 +172,8 @@ static void ipte_lock_siif(struct kvm *kvm)
retry:
read_lock(&kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(kvm);
old = READ_ONCE(*ic);
do {
old = READ_ONCE(*ic);
if (old.kg) {
read_unlock(&kvm->arch.sca_lock);
cond_resched();
@@ -182,7 +182,7 @@ static void ipte_lock_siif(struct kvm *kvm)
new = old;
new.k = 1;
new.kh++;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
} while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
}
@@ -192,13 +192,13 @@ static void ipte_unlock_siif(struct kvm *kvm)
read_lock(&kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(kvm);
old = READ_ONCE(*ic);
do {
old = READ_ONCE(*ic);
new = old;
new.kh--;
if (!new.kh)
new.k = 0;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
} while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
if (!new.kh)
wake_up(&kvm->arch.ipte_wq);

12
arch/s390/kvm/interrupt.c
View File

@@ -247,12 +247,12 @@ static inline int gisa_set_iam(struct kvm_s390_gisa *gisa, u8 iam)
{
u64 word, _word;
word = READ_ONCE(gisa->u64.word[0]);
do {
word = READ_ONCE(gisa->u64.word[0]);
if ((u64)gisa != word >> 32)
return -EBUSY;
_word = (word & ~0xffUL) | iam;
} while (cmpxchg(&gisa->u64.word[0], word, _word) != word);
} while (!try_cmpxchg(&gisa->u64.word[0], &word, _word));
return 0;
}
@@ -270,10 +270,10 @@ static inline void gisa_clear_ipm(struct kvm_s390_gisa *gisa)
{
u64 word, _word;
word = READ_ONCE(gisa->u64.word[0]);
do {
word = READ_ONCE(gisa->u64.word[0]);
_word = word & ~(0xffUL << 24);
} while (cmpxchg(&gisa->u64.word[0], word, _word) != word);
} while (!try_cmpxchg(&gisa->u64.word[0], &word, _word));
}
/**
@@ -291,14 +291,14 @@ static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
u8 pending_mask, alert_mask;
u64 word, _word;
word = READ_ONCE(gi->origin->u64.word[0]);
do {
word = READ_ONCE(gi->origin->u64.word[0]);
alert_mask = READ_ONCE(gi->alert.mask);
pending_mask = (u8)(word >> 24) & alert_mask;
if (pending_mask)
return pending_mask;
_word = (word & ~0xffUL) | alert_mask;
} while (cmpxchg(&gi->origin->u64.word[0], word, _word) != word);
} while (!try_cmpxchg(&gi->origin->u64.word[0], &word, _word));
return 0;
}

4
arch/s390/kvm/kvm-s390.c
View File

@@ -1907,11 +1907,11 @@ static void kvm_s390_update_topology_change_report(struct kvm *kvm, bool val)
read_lock(&kvm->arch.sca_lock);
sca = kvm->arch.sca;
old = READ_ONCE(sca->utility);
do {
old = READ_ONCE(sca->utility);
new = old;
new.mtcr = val;
} while (cmpxchg(&sca->utility.val, old.val, new.val) != old.val);
} while (!try_cmpxchg(&sca->utility.val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
}

5
arch/s390/kvm/pci.c
View File

@@ -208,13 +208,12 @@ static inline int account_mem(unsigned long nr_pages)
page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
cur_pages = atomic_long_read(&user->locked_vm);
do {
cur_pages = atomic_long_read(&user->locked_vm);
new_pages = cur_pages + nr_pages;
if (new_pages > page_limit)
return -ENOMEM;
} while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
new_pages) != cur_pages);
} while (!atomic_long_try_cmpxchg(&user->locked_vm, &cur_pages, new_pages));
atomic64_add(nr_pages, &current->mm->pinned_vm);