KVM: s390: interface to query and configure cpu features

For now, we only have an interface to query and configure facilities
indicated via STFL(E). However, we also have features indicated via
SCLP, that have to be indicated to the guest by user space and usually
require KVM support.

This patch allows user space to query and configure available cpu features
for the guest.

Please note that disabling a feature doesn't necessarily mean that it is
completely disabled (e.g. ESOP is mostly handled by the SIE). We will try
our best to disable it.

Most features (e.g. SCLP) can't directly be forwarded, as most of them need
in addition to hardware support, support in KVM. As we later on want to
turn these features in KVM explicitly on/off (to simulate different
behavior), we have to filter all features provided by the hardware and
make them configurable.

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

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index c5ec4d31e5e3..52aa47e112d8 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -175,6 +175,12 @@ static inline int set_kvm_facility(u64 *fac_list, unsigned long nr)
 	return 0;
 }
 
+static inline int test_kvm_cpu_feat(struct kvm *kvm, unsigned long nr)
+{
+	WARN_ON_ONCE(nr >= KVM_S390_VM_CPU_FEAT_NR_BITS);
+	return test_bit_inv(nr, kvm->arch.cpu_feat);
+}
+
 /* are cpu states controlled by user space */
 static inline int kvm_s390_user_cpu_state_ctrl(struct kvm *kvm)
 {