KVM: s390: Fix ordering when adding to SCA

When adding a new vCPU to the SCA area, the validity bit in the MCN was
set before the pointer to the state description, potentially allowing
for a race.

Fix by setting the pointer before setting the bit.

Fixes: 14542a0a54 ("KVM: S390: Remove sca_lock")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260803124040.126471-13-imbrenda@linux.ibm.com>
This commit is contained in:
Claudio Imbrenda 2026-08-03 14:40:39 +02:00
parent 216c5289dd
commit 9187a9186d

View File

@ -3485,8 +3485,8 @@ static void sca_add_vcpu(struct kvm_vcpu *vcpu)
if (!kvm_s390_use_sca_entries())
return;
WRITE_ONCE(sca->cpu[vcpu->vcpu_id].sda, virt_to_phys(vcpu->arch.sie_block));
set_bit_inv(vcpu->vcpu_id, (unsigned long *)sca->mcn);
sca->cpu[vcpu->vcpu_id].sda = virt_to_phys(vcpu->arch.sie_block);
}
static int sca_can_add_vcpu(struct kvm *kvm, unsigned int id)