KVM: s390: Introduce switching code
This patch adds code that performs transparent switch to Extended
SCA on addition of 65th VCPU in a VM. Disposal of ESCA is added too.
The entier ESCA functionality, however, is still not enabled.
The enablement will be provided in a separate patch.
This patch also uses read/write lock protection of SCA and its subfields for
possible disposal at the BSCA-to-ESCA transition. While only Basic SCA needs such
a protection (for the swap), any SCA access is now guarded.
Signed-off-by: Eugene (jno) Dvurechenski <jno@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 06f7edb..d30db40 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -259,10 +259,14 @@
int ipte_lock_held(struct kvm_vcpu *vcpu)
{
- union ipte_control *ic = kvm_s390_get_ipte_control(vcpu->kvm);
+ if (vcpu->arch.sie_block->eca & 1) {
+ int rc;
- if (vcpu->arch.sie_block->eca & 1)
- return ic->kh != 0;
+ read_lock(&vcpu->kvm->arch.sca_lock);
+ rc = kvm_s390_get_ipte_control(vcpu->kvm)->kh != 0;
+ read_unlock(&vcpu->kvm->arch.sca_lock);
+ return rc;
+ }
return vcpu->kvm->arch.ipte_lock_count != 0;
}
@@ -274,16 +278,20 @@
vcpu->kvm->arch.ipte_lock_count++;
if (vcpu->kvm->arch.ipte_lock_count > 1)
goto out;
+retry:
+ read_lock(&vcpu->kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(vcpu->kvm);
do {
old = READ_ONCE(*ic);
- while (old.k) {
+ if (old.k) {
+ read_unlock(&vcpu->kvm->arch.sca_lock);
cond_resched();
- old = READ_ONCE(*ic);
+ goto retry;
}
new = old;
new.k = 1;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
+ read_unlock(&vcpu->kvm->arch.sca_lock);
out:
mutex_unlock(&vcpu->kvm->arch.ipte_mutex);
}
@@ -296,12 +304,14 @@
vcpu->kvm->arch.ipte_lock_count--;
if (vcpu->kvm->arch.ipte_lock_count)
goto out;
+ read_lock(&vcpu->kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(vcpu->kvm);
do {
old = READ_ONCE(*ic);
new = old;
new.k = 0;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
+ read_unlock(&vcpu->kvm->arch.sca_lock);
wake_up(&vcpu->kvm->arch.ipte_wq);
out:
mutex_unlock(&vcpu->kvm->arch.ipte_mutex);
@@ -311,23 +321,28 @@
{
union ipte_control old, new, *ic;
+retry:
+ read_lock(&vcpu->kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(vcpu->kvm);
do {
old = READ_ONCE(*ic);
- while (old.kg) {
+ if (old.kg) {
+ read_unlock(&vcpu->kvm->arch.sca_lock);
cond_resched();
- old = READ_ONCE(*ic);
+ goto retry;
}
new = old;
new.k = 1;
new.kh++;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
+ read_unlock(&vcpu->kvm->arch.sca_lock);
}
static void ipte_unlock_siif(struct kvm_vcpu *vcpu)
{
union ipte_control old, new, *ic;
+ read_lock(&vcpu->kvm->arch.sca_lock);
ic = kvm_s390_get_ipte_control(vcpu->kvm);
do {
old = READ_ONCE(*ic);
@@ -336,6 +351,7 @@
if (!new.kh)
new.k = 0;
} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
+ read_unlock(&vcpu->kvm->arch.sca_lock);
if (!new.kh)
wake_up(&vcpu->kvm->arch.ipte_wq);
}