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: stable@kernel.org
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 25 insertions, 11 deletions

diff --git a/arch/s390/include/asm/kvm.h b/arch/s390/include/asm/kvm.h
index 3dfcaeb5d7f4..82b32a100c7d 100644
--- a/arch/s390/include/asm/kvm.h
+++ b/arch/s390/include/asm/kvm.h
@@ -1,6 +1,5 @@
 #ifndef __LINUX_KVM_S390_H
 #define __LINUX_KVM_S390_H
-
 /*
  * asm-s390/kvm.h - KVM s390 specific structures and definitions
  *
@@ -15,6 +14,8 @@
  */
 #include <linux/types.h>
 
+#define __KVM_S390
+
 /* for KVM_GET_REGS and KVM_SET_REGS */
 struct kvm_regs {
         /* general purpose regs for s390 */
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 544505893c9f..f8bcaefd7d34 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -117,10 +117,16 @@ long kvm_arch_dev_ioctl(struct file *filp,
 
 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 */
@@ -420,8 +426,10 @@ static int kvm_arch_vcpu_ioctl_set_initial_psw(struct kvm_vcpu *vcpu, psw_t psw)
         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;
 }
@@ -509,9 +517,6 @@ rerun_vcpu:
 
         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:
@@ -520,6 +525,9 @@ rerun_vcpu:
                 BUG();
         }
 
+        vcpu->arch.sie_block->gpsw.mask = kvm_run->psw_mask;
+        vcpu->arch.sie_block->gpsw.addr = kvm_run->psw_addr;
+
         might_fault();
 
         do {
@@ -539,8 +547,6 @@ rerun_vcpu:
                 /* 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;
@@ -552,6 +558,9 @@ rerun_vcpu:
                 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);
 
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 92045a92d714..2d241da07236 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -181,6 +181,11 @@ struct kvm_run {
         __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 {
@@ -232,8 +237,6 @@ struct kvm_run {
                 /* KVM_EXIT_S390_SIEIC */
                 struct {
                         __u8 icptcode;
-                        __u64 mask; /* psw upper half */
-                        __u64 addr; /* psw lower half */
                         __u16 ipa;
                         __u32 ipb;
                 } s390_sieic;
@@ -492,6 +495,7 @@ struct kvm_ioeventfd {
 #ifdef __KVM_HAVE_VCPU_EVENTS
 #define KVM_CAP_VCPU_EVENTS 41
 #endif
+#define KVM_CAP_S390_PSW 42
 
 #ifdef KVM_CAP_IRQ_ROUTING