s390x/kvm: Put vm name, extended name and UUID into STSI322 SYSIB

KVM prefills the SYSIB, returned by STSI 3.2.2. This patch allows
userspace to intercept execution, and fill in the values, that are
known to qemu: machine name (8 chars), extended machine name (256
chars), extended machine name encoding (equals 2 for UTF-8) and UUID.

STSI322 qemu handler also finds a highest virtualization level in
level-3 virtualization stack that doesn't support Extended Names
(Ext Name delimiter) and propagates zero Ext Name to all levels below,
because this level is not capable of managing Extended Names of lower
levels.

Signed-off-by: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

target-s390x/cpu.h

@@ -865,9 +865,13 @@ struct sysib_322 {
         uint8_t  name[8];
         uint32_t caf;
         uint8_t  cpi[16];
-        uint8_t  res3[24];
+        uint8_t res5[3];
+        uint8_t ext_name_encoding;
+        uint32_t res3;
+        uint8_t uuid[16];
     } vm[8];
-    uint8_t res4[3552];
+    uint8_t res4[1504];
+    uint8_t ext_names[8][256];
 };
 
 /* MMU defines */

target-s390x/kvm.c

@@ -44,6 +44,7 @@
 #include "hw/s390x/s390-pci-inst.h"
 #include "hw/s390x/s390-pci-bus.h"
 #include "hw/s390x/ipl.h"
+#include "hw/s390x/ebcdic.h"
 
 /* #define DEBUG_KVM */
 
@@ -255,6 +256,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
     }
 
     kvm_vm_enable_cap(s, KVM_CAP_S390_USER_SIGP, 0);
+    kvm_vm_enable_cap(s, KVM_CAP_S390_USER_STSI, 0);
 
     return 0;
 }
@@ -1723,6 +1725,72 @@ static int handle_tsch(S390CPU *cpu)
     return ret;
 }
 
+static void insert_stsi_3_2_2(S390CPU *cpu, __u64 addr)
+{
+    struct sysib_322 sysib;
+    int del;
+
+    if (s390_cpu_virt_mem_read(cpu, addr, &sysib, sizeof(sysib))) {
+        return;
+    }
+    /* Shift the stack of Extended Names to prepare for our own data */
+    memmove(&sysib.ext_names[1], &sysib.ext_names[0],
+            sizeof(sysib.ext_names[0]) * (sysib.count - 1));
+    /* First virt level, that doesn't provide Ext Names delimits stack. It is
+     * assumed it's not capable of managing Extended Names for lower levels.
+     */
+    for (del = 1; del < sysib.count; del++) {
+        if (!sysib.vm[del].ext_name_encoding || !sysib.ext_names[del][0]) {
+            break;
+        }
+    }
+    if (del < sysib.count) {
+        memset(sysib.ext_names[del], 0,
+               sizeof(sysib.ext_names[0]) * (sysib.count - del));
+    }
+    /* Insert short machine name in EBCDIC, padded with blanks */
+    if (qemu_name) {
+        memset(sysib.vm[0].name, 0x40, sizeof(sysib.vm[0].name));
+        ebcdic_put(sysib.vm[0].name, qemu_name, MIN(sizeof(sysib.vm[0].name),
+                                                    strlen(qemu_name)));
+    }
+    sysib.vm[0].ext_name_encoding = 2; /* 2 = UTF-8 */
+    memset(sysib.ext_names[0], 0, sizeof(sysib.ext_names[0]));
+    /* If hypervisor specifies zero Extended Name in STSI322 SYSIB, it's
+     * considered by s390 as not capable of providing any Extended Name.
+     * Therefore if no name was specified on qemu invocation, we go with the
+     * same "KVMguest" default, which KVM has filled into short name field.
+     */
+    if (qemu_name) {
+        strncpy((char *)sysib.ext_names[0], qemu_name,
+                sizeof(sysib.ext_names[0]));
+    } else {
+        strcpy((char *)sysib.ext_names[0], "KVMguest");
+    }
+    /* Insert UUID */
+    memcpy(sysib.vm[0].uuid, qemu_uuid, sizeof(sysib.vm[0].uuid));
+
+    s390_cpu_virt_mem_write(cpu, addr, &sysib, sizeof(sysib));
+}
+
+static int handle_stsi(S390CPU *cpu)
+{
+    CPUState *cs = CPU(cpu);
+    struct kvm_run *run = cs->kvm_run;
+
+    switch (run->s390_stsi.fc) {
+    case 3:
+        if (run->s390_stsi.sel1 != 2 || run->s390_stsi.sel2 != 2) {
+            return 0;
+        }
+        /* Only sysib 3.2.2 needs post-handling for now. */
+        insert_stsi_3_2_2(cpu, run->s390_stsi.addr);
+        return 0;
+    default:
+        return 0;
+    }
+}
+
 static int kvm_arch_handle_debug_exit(S390CPU *cpu)
 {
     CPUState *cs = CPU(cpu);
@@ -1772,6 +1840,9 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
         case KVM_EXIT_S390_TSCH:
             ret = handle_tsch(cpu);
             break;
+        case KVM_EXIT_S390_STSI:
+            ret = handle_stsi(cpu);
+            break;
         case KVM_EXIT_DEBUG:
             ret = kvm_arch_handle_debug_exit(cpu);
             break;