KVM: s390: ucontrol: per vcpu address spaces

This patch introduces two ioctls for virtual cpus, that are only
valid for kernel virtual machines that are controlled by userspace.
Each virtual cpu has its individual address space in this mode of
operation, and each address space is backed by the gmap
implementation just like the address space for regular KVM guests.
KVM_S390_UCAS_MAP allows to map a part of the user's virtual address
space to the vcpu. Starting offset and length in both the user and
the vcpu address space need to be aligned to 1M.
KVM_S390_UCAS_UNMAP can be used to unmap a range of memory from a
virtual cpu in a similar way.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 49 insertions, 1 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f0937552175b..2d3248895def 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -233,6 +233,10 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
                 (__u64) vcpu->arch.sie_block)
                 vcpu->kvm->arch.sca->cpu[vcpu->vcpu_id].sda = 0;
         smp_mb();
+
+        if (kvm_is_ucontrol(vcpu->kvm))
+                gmap_free(vcpu->arch.gmap);
+
         free_page((unsigned long)(vcpu->arch.sie_block));
         kvm_vcpu_uninit(vcpu);
         kfree(vcpu);
@@ -263,12 +267,20 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
         kvm_free_vcpus(kvm);
         free_page((unsigned long)(kvm->arch.sca));
         debug_unregister(kvm->arch.dbf);
-        gmap_free(kvm->arch.gmap);
+        if (!kvm_is_ucontrol(kvm))
+                gmap_free(kvm->arch.gmap);
 }
 
 /* Section: vcpu related */
 int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 {
+        if (kvm_is_ucontrol(vcpu->kvm)) {
+                vcpu->arch.gmap = gmap_alloc(current->mm);
+                if (!vcpu->arch.gmap)
+                        return -ENOMEM;
+                return 0;
+        }
+
         vcpu->arch.gmap = vcpu->kvm->arch.gmap;
         return 0;
 }
@@ -687,6 +699,42 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
         case KVM_S390_INITIAL_RESET:
                 r = kvm_arch_vcpu_ioctl_initial_reset(vcpu);
                 break;
+#ifdef CONFIG_KVM_S390_UCONTROL
+        case KVM_S390_UCAS_MAP: {
+                struct kvm_s390_ucas_mapping ucasmap;
+
+                if (copy_from_user(&ucasmap, argp, sizeof(ucasmap))) {
+                        r = -EFAULT;
+                        break;
+                }
+
+                if (!kvm_is_ucontrol(vcpu->kvm)) {
+                        r = -EINVAL;
+                        break;
+                }
+
+                r = gmap_map_segment(vcpu->arch.gmap, ucasmap.user_addr,
+                                     ucasmap.vcpu_addr, ucasmap.length);
+                break;
+        }
+        case KVM_S390_UCAS_UNMAP: {
+                struct kvm_s390_ucas_mapping ucasmap;
+
+                if (copy_from_user(&ucasmap, argp, sizeof(ucasmap))) {
+                        r = -EFAULT;
+                        break;
+                }
+
+                if (!kvm_is_ucontrol(vcpu->kvm)) {
+                        r = -EINVAL;
+                        break;
+                }
+
+                r = gmap_unmap_segment(vcpu->arch.gmap, ucasmap.vcpu_addr,
+                        ucasmap.length);
+                break;
+        }
+#endif
         default:
                 r = -EINVAL;
         }