[PATCH 2/3] KVM: s390: Add storage key facility interpretation control

[Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>]

Up to now we always expected to have the storage key facility
available for our (non-VSIE) KVM guests. For huge page support, we
need to be able to disable it, so let's introduce that now.

Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
---
 arch/s390/include/asm/kvm_host.h |  1 +
 arch/s390/kvm/kvm-s390.c         |  1 +
 arch/s390/kvm/priv.c             | 22 +++++++++++++---------
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index b768754..ccbbd12 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -793,6 +793,7 @@ struct kvm_arch{
 	int use_irqchip;
 	int has_cmma;
 	int has_pfmfi;
+	int has_skf;
 	int user_cpu_state_ctrl;
 	int user_sigp;
 	int user_stsi;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 781aaf0..ddf3599 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2010,6 +2010,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	kvm->arch.css_support = 0;
 	kvm->arch.use_irqchip = 0;
 	kvm->arch.has_pfmfi = sclp.has_pfmfi;
+	kvm->arch.has_skf = sclp.has_skey;
 	kvm->arch.epoch = 0;
 
 	spin_lock_init(&kvm->arch.start_stop_lock);
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 908b579..c74ad22 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -208,19 +208,23 @@ int kvm_s390_skey_check_enable(struct kvm_vcpu *vcpu)
 	struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;
 
 	trace_kvm_s390_skey_related_inst(vcpu);
-	if (!(sie_block->ictl & (ICTL_ISKE | ICTL_SSKE | ICTL_RRBE)) &&
+	/* Already enabled? */
+	if (vcpu->kvm->arch.has_skf &&
+	    !(sie_block->ictl & (ICTL_ISKE | ICTL_SSKE | ICTL_RRBE)) &&
 	    !kvm_s390_test_cpuflags(vcpu, CPUSTAT_KSS))
 		return rc;
 
 	rc = s390_enable_skey();
 	VCPU_EVENT(vcpu, 3, "enabling storage keys for guest: %d", rc);
-	if (!rc) {
-		if (kvm_s390_test_cpuflags(vcpu, CPUSTAT_KSS))
-			kvm_s390_clear_cpuflags(vcpu, CPUSTAT_KSS);
-		else
-			sie_block->ictl &= ~(ICTL_ISKE | ICTL_SSKE |
-					     ICTL_RRBE);
-	}
+	if (rc)
+		return rc;
+
+	if (kvm_s390_test_cpuflags(vcpu, CPUSTAT_KSS))
+		kvm_s390_clear_cpuflags(vcpu, CPUSTAT_KSS);
+	if (!vcpu->kvm->arch.has_skf)
+		sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
+	else
+		sie_block->ictl &= ~(ICTL_ISKE | ICTL_SSKE | ICTL_RRBE);
 	return rc;
 }
 
@@ -231,7 +235,7 @@ static int try_handle_skey(struct kvm_vcpu *vcpu)
 	rc = kvm_s390_skey_check_enable(vcpu);
 	if (rc)
 		return rc;
-	if (sclp.has_skey) {
+	if (vcpu->kvm->arch.has_skf) {
 		/* with storage-key facility, SIE interprets it for us */
 		kvm_s390_retry_instr(vcpu);
 		VCPU_EVENT(vcpu, 4, "%s", "retrying storage key operation");
-- 
2.7.4