KVM: s390: add capability indicating COW support
Currently qemu/kvm on s390 uses a guest mapping that does not
allow the guest backing page table to be write-protected to
support older systems. On those older systems a host write
protection fault will be delivered to the guest.
Newer systems allow to write-protect the guest backing memory
and let the fault be delivered to the host, thus allowing COW.
Use a capability bit to tell qemu if that is possible.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 8d696cf..09f2b3a 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -616,6 +616,7 @@
#define KVM_CAP_KVMCLOCK_CTRL 76
#define KVM_CAP_SIGNAL_MSI 77
#define KVM_CAP_PPC_GET_SMMU_INFO 78
+#define KVM_CAP_S390_COW 79
#ifdef KVM_CAP_IRQ_ROUTING