KVM: s390: vsie: initial support for nested virtualization
This patch adds basic support for nested virtualization on s390x, called
VSIE (virtual SIE) and allows it to be used by the guest if the necessary
facilities are supported by the hardware and enabled for the guest.
In order to make this work, we have to shadow the sie control block
provided by guest 2. In order to gain some performance, we have to
reuse the same shadow blocks as good as possible. For now, we allow
as many shadow blocks as we have VCPUs (that way, every VCPU can run the
VSIE concurrently).
We have to watch out for the prefix getting unmapped out of our shadow
gmap and properly get the VCPU out of VSIE in that case, to fault the
prefix pages back in. We use the PROG_REQUEST bit for that purpose.
This patch is based on an initial prototype by Tobias Elpelt.
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/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index a890f7d..3fb1242 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -99,6 +99,7 @@
{ "instruction_stfl", VCPU_STAT(instruction_stfl) },
{ "instruction_tprot", VCPU_STAT(instruction_tprot) },
{ "instruction_sthyi", VCPU_STAT(instruction_sthyi) },
+ { "instruction_sie", VCPU_STAT(instruction_sie) },
{ "instruction_sigp_sense", VCPU_STAT(instruction_sigp_sense) },
{ "instruction_sigp_sense_running", VCPU_STAT(instruction_sigp_sense_running) },
{ "instruction_sigp_external_call", VCPU_STAT(instruction_sigp_external_call) },
@@ -142,6 +143,7 @@
static struct kvm_s390_vm_cpu_subfunc kvm_s390_available_subfunc;
static struct gmap_notifier gmap_notifier;
+static struct gmap_notifier vsie_gmap_notifier;
debug_info_t *kvm_s390_dbf;
/* Section: not file related */
@@ -187,6 +189,8 @@
{
gmap_notifier.notifier_call = kvm_gmap_notifier;
gmap_register_pte_notifier(&gmap_notifier);
+ vsie_gmap_notifier.notifier_call = kvm_s390_vsie_gmap_notifier;
+ gmap_register_pte_notifier(&vsie_gmap_notifier);
atomic_notifier_chain_register(&s390_epoch_delta_notifier,
&kvm_clock_notifier);
return 0;
@@ -195,6 +199,7 @@
void kvm_arch_hardware_unsetup(void)
{
gmap_unregister_pte_notifier(&gmap_notifier);
+ gmap_unregister_pte_notifier(&vsie_gmap_notifier);
atomic_notifier_chain_unregister(&s390_epoch_delta_notifier,
&kvm_clock_notifier);
}
@@ -252,6 +257,14 @@
if (MACHINE_HAS_ESOP)
allow_cpu_feat(KVM_S390_VM_CPU_FEAT_ESOP);
+ /*
+ * We need SIE support, ESOP (PROT_READ protection for gmap_shadow),
+ * 64bit SCAO (SCA passthrough) and IDTE (for gmap_shadow unshadowing).
+ */
+ if (!sclp.has_sief2 || !MACHINE_HAS_ESOP || !sclp.has_64bscao ||
+ !test_facility(3))
+ return;
+ allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIEF2);
}
int kvm_arch_init(void *opaque)
@@ -1406,6 +1419,7 @@
kvm->arch.epoch = 0;
spin_lock_init(&kvm->arch.start_stop_lock);
+ kvm_s390_vsie_init(kvm);
KVM_EVENT(3, "vm 0x%pK created by pid %u", kvm, current->pid);
return 0;
@@ -1463,6 +1477,7 @@
gmap_remove(kvm->arch.gmap);
kvm_s390_destroy_adapters(kvm);
kvm_s390_clear_float_irqs(kvm);
+ kvm_s390_vsie_destroy(kvm);
KVM_EVENT(3, "vm 0x%pK destroyed", kvm);
}