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/diag.c b/arch/s390/kvm/diag.c
index 3a74d8af0d69dd2e3bac77a427a6bfd64723bae9..78d967f180f4adc088aea609df1cc664ad57b917 100644 (file)
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -107,14 +107,13 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
 
 static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
 {
-       int ret, idx;
+       int ret;
 
        /* No virtio-ccw notification? Get out quickly. */
        if (!vcpu->kvm->arch.css_support ||
            (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
                return -EOPNOTSUPP;
 
-       idx = srcu_read_lock(&vcpu->kvm->srcu);
        /*
         * The layout is as follows:
         * - gpr 2 contains the subchannel id (passed as addr)
@@ -125,7 +124,6 @@ static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
                                      vcpu->run->s.regs.gprs[2],
                                      8, &vcpu->run->s.regs.gprs[3],
                                      vcpu->run->s.regs.gprs[4]);
-       srcu_read_unlock(&vcpu->kvm->srcu, idx);
 
        /*
         * Return cookie in gpr 2, but don't overwrite the register if the

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 7f35cb33e5102008244b4fd1376954400f2d0009..e7323cd9f1098dc57cec3f21382330cdbf6a84f8 100644 (file)
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -436,6 +436,7 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
        hrtimer_start(&vcpu->arch.ckc_timer, ktime_set (0, sltime) , HRTIMER_MODE_REL);
        VCPU_EVENT(vcpu, 5, "enabled wait via clock comparator: %llx ns", sltime);
 no_timer:
+       srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
        spin_lock(&vcpu->arch.local_int.float_int->lock);
        spin_lock_bh(&vcpu->arch.local_int.lock);
        add_wait_queue(&vcpu->wq, &wait);
@@ -455,6 +456,8 @@ no_timer:
        remove_wait_queue(&vcpu->wq, &wait);
        spin_unlock_bh(&vcpu->arch.local_int.lock);
        spin_unlock(&vcpu->arch.local_int.float_int->lock);
+       vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+
        hrtimer_try_to_cancel(&vcpu->arch.ckc_timer);
        return 0;
 }

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 8eec7abc5664f36f23949093b677c0759a71e16f..1e4e7b97337a8a72b8820a77a3f99e6232618bcc 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -752,11 +752,18 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 {
        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 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
                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 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 {
        struct kvm_vcpu *vcpu = filp->private_data;
        void __user *argp = (void __user *)arg;
+       int idx;
        long r;
 
        switch (ioctl) {
@@ -981,7 +991,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                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;