KVM: s390: PSW forwarding / rewinding / ilc rework

We have some confusion about ilc vs. ilen in our current code. So let's
correctly use the term ilen when dealing with (ilc << 1).

Program irq injection didn't take care of the correct ilc in case of
irqs triggered by EXECUTE functions, let's provide one function
kvm_s390_get_ilen() to take care of all that.

Also, manually specifying in intercept handlers the size of the
instruction (and sometimes overwriting that value for EXECUTE internally)
doesn't make too much sense. So also provide the functions:
- kvm_s390_retry_instr to retry the currently intercepted instruction
- kvm_s390_rewind_psw to rewind the PSW without internal overwrites
- kvm_s390_forward_psw to forward the PSW

Reviewed-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>

1 files changed, 23 insertions, 8 deletions

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index d53c10753c46..7f992e02124a 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -38,17 +38,32 @@ static const intercept_handler_t instruction_handlers[256] = {
 	[0xeb] = kvm_s390_handle_eb,
 };
 
-void kvm_s390_rewind_psw(struct kvm_vcpu *vcpu, int ilc)
+u8 kvm_s390_get_ilen(struct kvm_vcpu *vcpu)
 {
 	struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;
+	u8 ilen = 0;
 
-	/* Use the length of the EXECUTE instruction if necessary */
-	if (sie_block->icptstatus & 1) {
-		ilc = (sie_block->icptstatus >> 4) & 0x6;
-		if (!ilc)
-			ilc = 4;
+	switch (vcpu->arch.sie_block->icptcode) {
+	case ICPT_INST:
+	case ICPT_INSTPROGI:
+	case ICPT_OPEREXC:
+	case ICPT_PARTEXEC:
+	case ICPT_IOINST:
+		/* instruction only stored for these icptcodes */
+		ilen = insn_length(vcpu->arch.sie_block->ipa >> 8);
+		/* Use the length of the EXECUTE instruction if necessary */
+		if (sie_block->icptstatus & 1) {
+			ilen = (sie_block->icptstatus >> 4) & 0x6;
+			if (!ilen)
+				ilen = 4;
+		}
+		break;
+	case ICPT_PROGI:
+		/* bit 1+2 of pgmilc are the ilc, so we directly get ilen */
+		ilen = vcpu->arch.sie_block->pgmilc & 0x6;
+		break;
 	}
-	sie_block->gpsw.addr = __rewind_psw(sie_block->gpsw, ilc);
+	return ilen;
 }
 
 static int handle_noop(struct kvm_vcpu *vcpu)
@@ -318,7 +333,7 @@ static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
 	if (rc != 0)
 		return rc;
 
-	kvm_s390_rewind_psw(vcpu, 4);
+	kvm_s390_retry_instr(vcpu);
 
 	return 0;
 }