KVM: s390: ucontrol: export SIE control block to user

This patch exports the s390 SIE hardware control block to userspace
via the mapping of the vcpu file descriptor. In order to do so,
a new arch callback named kvm_arch_vcpu_fault  is introduced for all
architectures. It allows to map architecture specific pages.

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>

include/linux/kvm.h

@@ -440,6 +440,8 @@ struct kvm_ppc_pvinfo {
 /* machine type bits, to be used as argument to KVM_CREATE_VM */
 #define KVM_VM_S390_UCONTROL	1
 
+#define KVM_S390_SIE_PAGE_OFFSET 1
+
 /*
  * ioctls for /dev/kvm fds:
  */

include/linux/kvm_host.h

@@ -450,6 +450,7 @@ long kvm_arch_dev_ioctl(struct file *filp,
 			unsigned int ioctl, unsigned long arg);
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg);
+int kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf);
 
 int kvm_dev_ioctl_check_extension(long ext);