KVM: s390: Make psw available on all exits, not just a subset

This patch moves s390 processor status word into the base kvm_run
struct and keeps it up-to date on all userspace exits.

The userspace ABI is broken by this, however there are no applications
in the wild using this. A capability check is provided so users can
verify the updated API exists.

Cc: [e-mail]
Signed-off-by: Carsten Otte <[e-mail]>
Signed-off-by: Avi Kivity <[e-mail]>

arch/s390/include/asm/kvm.h

···
 #ifndef __LINUX_KVM_S390_H
 #define __LINUX_KVM_S390_H
-
 /*
  * asm-s390/kvm.h - KVM s390 specific structures and definitions
  *
···
  *               Christian Borntraeger <[e-mail]>
  */
 #include <linux/types.h>
+
+#define __KVM_S390
 
 /* for KVM_GET_REGS and KVM_SET_REGS */
 struct kvm_regs {

arch/s390/kvm/kvm-s390.c

···
 
 int kvm_dev_ioctl_check_extension(long ext)
 {
+	int r;
+
 	switch (ext) {
+	case KVM_CAP_S390_PSW:
+		r = 1;
+		break;
 	default:
-		return 0;
+		r = 0;
 	}
+	return r;
 }
 
 /* Section: vm related */
···
 	vcpu_load(vcpu);
 	if (atomic_read(&vcpu->arch.sie_block->cpuflags) & CPUSTAT_RUNNING)
 		rc = -EBUSY;
-	else
-		vcpu->arch.sie_block->gpsw = psw;
+	else {
+		vcpu->run->psw_mask = psw.mask;
+		vcpu->run->psw_addr = psw.addr;
+	}
 	vcpu_put(vcpu);
 	return rc;
 }
···
 
 	switch (kvm_run->exit_reason) {
 	case KVM_EXIT_S390_SIEIC:
-		vcpu->arch.sie_block->gpsw.mask = kvm_run->s390_sieic.mask;
-		vcpu->arch.sie_block->gpsw.addr = kvm_run->s390_sieic.addr;
-		break;
 	case KVM_EXIT_UNKNOWN:
 	case KVM_EXIT_INTR:
 	case KVM_EXIT_S390_RESET:
···
 	default:
 		BUG();
 	}
+
+	vcpu->arch.sie_block->gpsw.mask = kvm_run->psw_mask;
+	vcpu->arch.sie_block->gpsw.addr = kvm_run->psw_addr;
 
 	might_fault();
 
···
 		/* intercept cannot be handled in-kernel, prepare kvm-run */
 		kvm_run->exit_reason         = KVM_EXIT_S390_SIEIC;
 		kvm_run->s390_sieic.icptcode = vcpu->arch.sie_block->icptcode;
-		kvm_run->s390_sieic.mask     = vcpu->arch.sie_block->gpsw.mask;
-		kvm_run->s390_sieic.addr     = vcpu->arch.sie_block->gpsw.addr;
 		kvm_run->s390_sieic.ipa      = vcpu->arch.sie_block->ipa;
 		kvm_run->s390_sieic.ipb      = vcpu->arch.sie_block->ipb;
 		rc = 0;
···
 		 * kvm_run has been prepared by the handler */
 		rc = 0;
 	}
+
+	kvm_run->psw_mask     = vcpu->arch.sie_block->gpsw.mask;
+	kvm_run->psw_addr     = vcpu->arch.sie_block->gpsw.addr;
 
 	if (vcpu->sigset_active)
 		sigprocmask(SIG_SETMASK, &sigsaved, NULL);

include/linux/kvm.h

···
 	__u64 cr8;
 	__u64 apic_base;
 
+#ifdef __KVM_S390
+	/* the processor status word for s390 */
+	__u64 psw_mask; /* psw upper half */
+	__u64 psw_addr; /* psw lower half */
+#endif
 	union {
 		/* KVM_EXIT_UNKNOWN */
 		struct {
···
 		/* KVM_EXIT_S390_SIEIC */
 		struct {
 			__u8 icptcode;
-			__u64 mask; /* psw upper half */
-			__u64 addr; /* psw lower half */
 			__u16 ipa;
 			__u32 ipb;
 		} s390_sieic;
···
 #ifdef __KVM_HAVE_VCPU_EVENTS
 #define KVM_CAP_VCPU_EVENTS 41
 #endif
+#define KVM_CAP_S390_PSW 42
 
 #ifdef KVM_CAP_IRQ_ROUTING