KVM: s390: Lock kvm->srcu at the appropriate places
The kvm->srcu lock has to be held while accessing the memory of
guests and during certain other actions. This patch now adds
the locks to the __vcpu_run function so that all affected code
is protected now (and additionally to the KVM_S390_STORE_STATUS
ioctl, which can be called out-of-band and needs a separate lock).
Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 8eec7ab..1e4e7b9 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -752,11 +752,18 @@
{
int rc, exit_reason;
+ /*
+ * We try to hold kvm->srcu during most of vcpu_run (except when run-
+ * ning the guest), so that memslots (and other stuff) are protected
+ */
+ vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+
do {
rc = vcpu_pre_run(vcpu);
if (rc)
break;
+ srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
/*
* As PF_VCPU will be used in fault handler, between
* guest_enter and guest_exit should be no uaccess.
@@ -767,10 +774,12 @@
exit_reason = sie64a(vcpu->arch.sie_block,
vcpu->run->s.regs.gprs);
kvm_guest_exit();
+ vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
rc = vcpu_post_run(vcpu, exit_reason);
} while (!signal_pending(current) && !rc);
+ srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
return rc;
}
@@ -968,6 +977,7 @@
{
struct kvm_vcpu *vcpu = filp->private_data;
void __user *argp = (void __user *)arg;
+ int idx;
long r;
switch (ioctl) {
@@ -981,7 +991,9 @@
break;
}
case KVM_S390_STORE_STATUS:
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
r = kvm_s390_vcpu_store_status(vcpu, arg);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
break;
case KVM_S390_SET_INITIAL_PSW: {
psw_t psw;