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| author | Heiko Carstens <hca@linux.ibm.com> | 2023-01-09 15:54:56 +0100 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2023-01-11 15:28:47 +0100 |
| commit | 42400d99e9f0728c17240edb9645637ead40f6b9 (patch) | |
| tree | a31270d8eb3bfa5e7f7fce4895528c70af882389 /arch | |
| parent | e3f360db08d55a14112bd27454e616a24296a8b0 (diff) | |
| download | linux-42400d99e9f0728c17240edb9645637ead40f6b9.tar.bz2 | |
KVM: s390: interrupt: use READ_ONCE() before cmpxchg()
Use READ_ONCE() before cmpxchg() to prevent that the compiler generates
code that fetches the to be compared old value several times from memory.
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20230109145456.2895385-1-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/kvm/interrupt.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 1dae78deddf2..ab26aa53ee37 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -83,8 +83,9 @@ static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) struct esca_block *sca = vcpu->kvm->arch.sca; union esca_sigp_ctrl *sigp_ctrl = &(sca->cpu[vcpu->vcpu_id].sigp_ctrl); - union esca_sigp_ctrl new_val = {0}, old_val = *sigp_ctrl; + union esca_sigp_ctrl new_val = {0}, old_val; + old_val = READ_ONCE(*sigp_ctrl); new_val.scn = src_id; new_val.c = 1; old_val.c = 0; @@ -95,8 +96,9 @@ static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) struct bsca_block *sca = vcpu->kvm->arch.sca; union bsca_sigp_ctrl *sigp_ctrl = &(sca->cpu[vcpu->vcpu_id].sigp_ctrl); - union bsca_sigp_ctrl new_val = {0}, old_val = *sigp_ctrl; + union bsca_sigp_ctrl new_val = {0}, old_val; + old_val = READ_ONCE(*sigp_ctrl); new_val.scn = src_id; new_val.c = 1; old_val.c = 0; @@ -126,16 +128,18 @@ static void sca_clear_ext_call(struct kvm_vcpu *vcpu) struct esca_block *sca = vcpu->kvm->arch.sca; union esca_sigp_ctrl *sigp_ctrl = &(sca->cpu[vcpu->vcpu_id].sigp_ctrl); - union esca_sigp_ctrl old = *sigp_ctrl; + union esca_sigp_ctrl old; + old = READ_ONCE(*sigp_ctrl); expect = old.value; rc = cmpxchg(&sigp_ctrl->value, old.value, 0); } else { struct bsca_block *sca = vcpu->kvm->arch.sca; union bsca_sigp_ctrl *sigp_ctrl = &(sca->cpu[vcpu->vcpu_id].sigp_ctrl); - union bsca_sigp_ctrl old = *sigp_ctrl; + union bsca_sigp_ctrl old; + old = READ_ONCE(*sigp_ctrl); expect = old.value; rc = cmpxchg(&sigp_ctrl->value, old.value, 0); } |