KVM: s390: vsie: add indication for future features

We have certain SIE features that we cannot support for now.
Let's add these features, so user space can directly prepare to enable
them, so we don't have to update yet another component.

In addition, add a comment block, telling why it is for now not possible to
forward/enable these features.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index c128567d1cd3c5badf0dfde6d1125ce70b2aa1f6..a2ffec4139ad1cb8cebe816a9f0b3e261cd97d42 100644 (file)
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -106,6 +106,10 @@ struct kvm_s390_vm_cpu_machine {
 #define KVM_S390_VM_CPU_FEAT_IB                6
 #define KVM_S390_VM_CPU_FEAT_CEI       7
 #define KVM_S390_VM_CPU_FEAT_IBS       8
+#define KVM_S390_VM_CPU_FEAT_SKEY      9
+#define KVM_S390_VM_CPU_FEAT_CMMA      10
+#define KVM_S390_VM_CPU_FEAT_PFMFI     11
+#define KVM_S390_VM_CPU_FEAT_SIGPIF    12
 struct kvm_s390_vm_cpu_feat {
        __u64 feat[16];
 };

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6fdf1f7647d7c9cb362b0221bba80a33dd7654b4..31cf22f7d846bd7a2572c2c2f46d5027de06c263 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -281,6 +281,24 @@ static void kvm_s390_cpu_feat_init(void)
                allow_cpu_feat(KVM_S390_VM_CPU_FEAT_CEI);
        if (sclp.has_ibs)
                allow_cpu_feat(KVM_S390_VM_CPU_FEAT_IBS);
+       /*
+        * KVM_S390_VM_CPU_FEAT_SKEY: Wrong shadow of PTE.I bits will make
+        * all skey handling functions read/set the skey from the PGSTE
+        * instead of the real storage key.
+        *
+        * KVM_S390_VM_CPU_FEAT_CMMA: Wrong shadow of PTE.I bits will make
+        * pages being detected as preserved although they are resident.
+        *
+        * KVM_S390_VM_CPU_FEAT_PFMFI: Wrong shadow of PTE.I bits will
+        * have the same effect as for KVM_S390_VM_CPU_FEAT_SKEY.
+        *
+        * For KVM_S390_VM_CPU_FEAT_SKEY, KVM_S390_VM_CPU_FEAT_CMMA and
+        * KVM_S390_VM_CPU_FEAT_PFMFI, all PTE.I and PGSTE bits have to be
+        * correctly shadowed. We can do that for the PGSTE but not for PTE.I.
+        *
+        * KVM_S390_VM_CPU_FEAT_SIGPIF: Wrong SCB addresses in the SCA. We
+        * cannot easily shadow the SCA because of the ipte lock.
+        */
 }
 
 int kvm_arch_init(void *opaque)