[RFCv2 12/37] KVM: s390: protvirt: Handle SE notification interceptions

[Christian Borntraeger <borntraeger@de.ibm.com>]

From: Janosch Frank <frankja@linux.ibm.com>

Since KVM doesn't emulate any form of load control and load psw
instructions anymore, we wouldn't get an interception if PSWs or CRs
are changed in the guest. That means we can't inject IRQs right after
the guest is enabled for them.

The new interception codes solve that problem by being a notification
for changes to IRQ enablement relevant bits in CRs 0, 6 and 14, as
well a the machine check mask bit in the PSW.

No special handling is needed for these interception codes, the KVM
pre-run code will consult all necessary CRs and PSW bits and inject
IRQs the guest is enabled for.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  2 ++
 arch/s390/kvm/intercept.c        | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 841690d05080..d63ed05272ec 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -215,6 +215,8 @@ struct kvm_s390_sie_block {
 #define ICPT_PARTEXEC	0x38
 #define ICPT_IOINST	0x40
 #define ICPT_KSS	0x5c
+#define ICPT_PV_MCHKR	0x60
+#define ICPT_PV_INT_EN	0x64
 	__u8	icptcode;		/* 0x0050 */
 	__u8	icptstatus;		/* 0x0051 */
 	__u16	ihcpu;			/* 0x0052 */
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index a389fa85cca2..eaa2a21c3170 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -480,6 +480,16 @@ int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
 	case ICPT_KSS:
 		rc = kvm_s390_skey_check_enable(vcpu);
 		break;
+	case ICPT_PV_MCHKR:
+		/* fallthrough */
+	case ICPT_PV_INT_EN:
+		/*
+		 * PSW bit 13 or a CR (0, 6, 14) changed and we might
+		 * now be able to deliver interrupts. The pre-run code
+		 * will take care of this.
+		 */
+		rc = 0;
+		break;
 	default:
 		return -EOPNOTSUPP;
 	}
-- 
2.24.0