KVM: s390: fix SCA related races and double use
If something goes wrong in kvm_arch_vcpu_create, the VCPU has already
been added to the sca but will never be removed. Trying to create VCPUs
with duplicate ids (e.g. after a failed attempt) is problematic.
Also, when creating multiple VCPUs in parallel, we could theoretically
forget to set the correct SCA when the switch to ESCA happens just
before the VCPU is registered.
Let's add the VCPU to the SCA in kvm_arch_vcpu_postcreate, where we can
be sure that no duplicate VCPU with the same id is around and the VCPU
has already been registered at the VM. We also have to make sure to update
ECB at that point.
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 5c58127..2ba5978 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1289,6 +1289,7 @@
sca->cpu[id].sda = (__u64) vcpu->arch.sie_block;
vcpu->arch.sie_block->scaoh = (__u32)(((__u64)sca) >> 32);
vcpu->arch.sie_block->scaol = (__u32)(__u64)sca & ~0x3fU;
+ vcpu->arch.sie_block->ecb2 |= 0x04U;
set_bit_inv(id, (unsigned long *) sca->mcn);
} else {
struct bsca_block *sca = kvm->arch.sca;
@@ -1493,8 +1494,11 @@
vcpu->arch.sie_block->epoch = vcpu->kvm->arch.epoch;
preempt_enable();
mutex_unlock(&vcpu->kvm->lock);
- if (!kvm_is_ucontrol(vcpu->kvm))
+ if (!kvm_is_ucontrol(vcpu->kvm)) {
vcpu->arch.gmap = vcpu->kvm->arch.gmap;
+ sca_add_vcpu(vcpu, vcpu->kvm, vcpu->vcpu_id);
+ }
+
}
static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu)
@@ -1558,8 +1562,6 @@
vcpu->arch.sie_block->ecb |= 0x10;
vcpu->arch.sie_block->ecb2 = 8;
- if (vcpu->kvm->arch.use_esca)
- vcpu->arch.sie_block->ecb2 |= 4;
vcpu->arch.sie_block->eca = 0xC1002000U;
if (sclp.has_siif)
vcpu->arch.sie_block->eca |= 1;
@@ -1608,9 +1610,6 @@
vcpu->arch.sie_block->itdba = (unsigned long) &sie_page->itdb;
vcpu->arch.sie_block->icpua = id;
- if (!kvm_is_ucontrol(kvm))
- sca_add_vcpu(vcpu, kvm, id);
-
spin_lock_init(&vcpu->arch.local_int.lock);
vcpu->arch.local_int.float_int = &kvm->arch.float_int;
vcpu->arch.local_int.wq = &vcpu->wq;