1 files changed, 31 insertions, 5 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f4d56e9939c9..86567e174fd7 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -657,6 +657,8 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
                                 struct kvm_memory_slot old,
                                 int user_alloc)
 {
+        int i;
+
         /* A few sanity checks. We can have exactly one memory slot which has
            to start at guest virtual zero and which has to be located at a
            page boundary in userland and which has to end at a page boundary.
@@ -664,7 +666,7 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
            vmas. It is okay to mmap() and munmap() stuff in this slot after
            doing this call at any time */
 
-        if (mem->slot)
+        if (mem->slot || kvm->arch.guest_memsize)
                 return -EINVAL;
 
         if (mem->guest_phys_addr)
@@ -676,15 +678,39 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
         if (mem->memory_size & (PAGE_SIZE - 1))
                 return -EINVAL;
 
+        if (!user_alloc)
+                return -EINVAL;
+
+        /* lock all vcpus */
+        for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+                if (!kvm->vcpus[i])
+                        continue;
+                if (!mutex_trylock(&kvm->vcpus[i]->mutex))
+                        goto fail_out;
+        }
+
         kvm->arch.guest_origin = mem->userspace_addr;
         kvm->arch.guest_memsize = mem->memory_size;
 
-        /* FIXME: we do want to interrupt running CPUs and update their memory
-           configuration now to avoid race conditions. But hey, changing the
-           memory layout while virtual CPUs are running is usually bad
-           programming practice. */
+        /* update sie control blocks, and unlock all vcpus */
+        for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+                if (kvm->vcpus[i]) {
+                        kvm->vcpus[i]->arch.sie_block->gmsor =
+                                kvm->arch.guest_origin;
+                        kvm->vcpus[i]->arch.sie_block->gmslm =
+                                kvm->arch.guest_memsize +
+                                kvm->arch.guest_origin +
+                                VIRTIODESCSPACE - 1ul;
+                        mutex_unlock(&kvm->vcpus[i]->mutex);
+                }
+        }
 
         return 0;
+
+fail_out:
+        for (; i >= 0; i--)
+                mutex_unlock(&kvm->vcpus[i]->mutex);
+        return -EINVAL;
 }
 
 void kvm_arch_flush_shadow(struct kvm *kvm)