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| author | Radim Krčmář <rkrcmar@redhat.com> | 2018-01-24 16:25:53 +0100 |
|---|---|---|
| committer | Radim Krčmář <rkrcmar@redhat.com> | 2018-01-24 16:25:53 +0100 |
| commit | bda646dd182a90ba4239fc62b71eb8b73126fa77 (patch) | |
| tree | 20d8139459e5ba7dd137c4471f3e655ddb70b03e | |
| parent | Linux 4.15-rc9 (diff) | |
| parent | KVM: s390: add proper locking for CMMA migration bitmap (diff) | |
| download | linux-bda646dd182a90ba4239fc62b71eb8b73126fa77.tar.xz linux-bda646dd182a90ba4239fc62b71eb8b73126fa77.zip | |
Merge tag 'kvm-s390-master-4.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux
KVM: s390: another fix for cmma migration
This fixes races and potential use after free in the
cmma migration code.
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 2598cf243b86..1371dff2b90d 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -769,7 +769,7 @@ static void kvm_s390_sync_request_broadcast(struct kvm *kvm, int req) /* * Must be called with kvm->srcu held to avoid races on memslots, and with - * kvm->lock to avoid races with ourselves and kvm_s390_vm_stop_migration. + * kvm->slots_lock to avoid races with ourselves and kvm_s390_vm_stop_migration. */ static int kvm_s390_vm_start_migration(struct kvm *kvm) { @@ -825,7 +825,7 @@ static int kvm_s390_vm_start_migration(struct kvm *kvm) } /* - * Must be called with kvm->lock to avoid races with ourselves and + * Must be called with kvm->slots_lock to avoid races with ourselves and * kvm_s390_vm_start_migration. */ static int kvm_s390_vm_stop_migration(struct kvm *kvm) @@ -840,6 +840,8 @@ static int kvm_s390_vm_stop_migration(struct kvm *kvm) if (kvm->arch.use_cmma) { kvm_s390_sync_request_broadcast(kvm, KVM_REQ_STOP_MIGRATION); + /* We have to wait for the essa emulation to finish */ + synchronize_srcu(&kvm->srcu); vfree(mgs->pgste_bitmap); } kfree(mgs); @@ -849,14 +851,12 @@ static int kvm_s390_vm_stop_migration(struct kvm *kvm) static int kvm_s390_vm_set_migration(struct kvm *kvm, struct kvm_device_attr *attr) { - int idx, res = -ENXIO; + int res = -ENXIO; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->slots_lock); switch (attr->attr) { case KVM_S390_VM_MIGRATION_START: - idx = srcu_read_lock(&kvm->srcu); res = kvm_s390_vm_start_migration(kvm); - srcu_read_unlock(&kvm->srcu, idx); break; case KVM_S390_VM_MIGRATION_STOP: res = kvm_s390_vm_stop_migration(kvm); @@ -864,7 +864,7 @@ static int kvm_s390_vm_set_migration(struct kvm *kvm, default: break; } - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->slots_lock); return res; } @@ -1754,7 +1754,9 @@ long kvm_arch_vm_ioctl(struct file *filp, r = -EFAULT; if (copy_from_user(&args, argp, sizeof(args))) break; + mutex_lock(&kvm->slots_lock); r = kvm_s390_get_cmma_bits(kvm, &args); + mutex_unlock(&kvm->slots_lock); if (!r) { r = copy_to_user(argp, &args, sizeof(args)); if (r) @@ -1768,7 +1770,9 @@ long kvm_arch_vm_ioctl(struct file *filp, r = -EFAULT; if (copy_from_user(&args, argp, sizeof(args))) break; + mutex_lock(&kvm->slots_lock); r = kvm_s390_set_cmma_bits(kvm, &args); + mutex_unlock(&kvm->slots_lock); break; } default: |