[Qemu-devel] [PATCH v2 2/3] s390: cpu feature for diagnose 318 andlimit max VCPUs to 247

[Collin Walling <walling@linux.ibm.com>]

Diagnose 318 is a new z14.2 CPU feature. Since we are able to emulate
it entirely via KVM, we can add guest support for earlier models. A
new CPU feature for diagnose 318 (shortened to diag318) will be made
available to guests starting with the zEC12-full CPU model.

The z14.2 adds a new read SCP info byte (let's call it byte 134) to
detect the availability of diag318. Because of this, we have room for
one less VCPU and thus limit the max VPUs supported in a configuration
to 247 (down from 248).

Signed-off-by: Collin Walling <walling@linux.ibm.com>.
---
 hw/s390x/sclp.c                 | 2 ++
 include/hw/s390x/sclp.h         | 2 ++
 target/s390x/cpu.h              | 2 +-
 target/s390x/cpu_features.c     | 3 +++
 target/s390x/cpu_features.h     | 1 +
 target/s390x/cpu_features_def.h | 3 +++
 target/s390x/gen-features.c     | 1 +
 target/s390x/kvm.c              | 1 +
 8 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
index 4510a80..183c627 100644
--- a/hw/s390x/sclp.c
+++ b/hw/s390x/sclp.c
@@ -73,6 +73,8 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
                          read_info->conf_char);
     s390_get_feat_block(S390_FEAT_TYPE_SCLP_CONF_CHAR_EXT,
                          read_info->conf_char_ext);
+    /* Read Info byte 134 */
+    s390_get_feat_block(S390_FEAT_TYPE_SCLP_BYTE_134, read_info->byte_134);
 
     read_info->facilities = cpu_to_be64(SCLP_HAS_CPU_INFO |
                                         SCLP_HAS_IOA_RECONFIG);
diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
index f9db243..eb12ba2 100644
--- a/include/hw/s390x/sclp.h
+++ b/include/hw/s390x/sclp.h
@@ -133,6 +133,8 @@ typedef struct ReadInfo {
     uint16_t highest_cpu;
     uint8_t  _reserved5[124 - 122];     /* 122-123 */
     uint32_t hmfai;
+    uint8_t  _reserved7[134 - 128];     /* 128-133 */
+    uint8_t  byte_134[1];
     struct CPUEntry entries[0];
 } QEMU_PACKED ReadInfo;
 
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 8c2320e..594b4a4 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -52,7 +52,7 @@
 
 #define MMU_USER_IDX 0
 
-#define S390_MAX_CPUS 248
+#define S390_MAX_CPUS 247
 
 typedef struct PSW {
     uint64_t mask;
diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index 60cfeba..d05afa5 100644
--- a/target/s390x/cpu_features.c
+++ b/target/s390x/cpu_features.c
@@ -121,6 +121,9 @@ static const S390FeatDef s390_features[] = {
     FEAT_INIT("pfmfi", S390_FEAT_TYPE_SCLP_CONF_CHAR_EXT, 9, "SIE: PFMF interpretation facility"),
     FEAT_INIT("ibs", S390_FEAT_TYPE_SCLP_CONF_CHAR_EXT, 10, "SIE: Interlock-and-broadcast-suppression facility"),
 
+    /* SCLP SCCB Byte 134 */
+    FEAT_INIT("diag318", S390_FEAT_TYPE_SCLP_BYTE_134, 0, "SIE: Diagnose 318"),
+
     FEAT_INIT("sief2", S390_FEAT_TYPE_SCLP_CPU, 4, "SIE: interception format 2 (Virtual SIE)"),
     FEAT_INIT("skey", S390_FEAT_TYPE_SCLP_CPU, 5, "SIE: Storage-key facility"),
     FEAT_INIT("gpereh", S390_FEAT_TYPE_SCLP_CPU, 10, "SIE: Guest-PER enhancement facility"),
diff --git a/target/s390x/cpu_features.h b/target/s390x/cpu_features.h
index effe790..e7248df 100644
--- a/target/s390x/cpu_features.h
+++ b/target/s390x/cpu_features.h
@@ -23,6 +23,7 @@ typedef enum {
     S390_FEAT_TYPE_STFL,
     S390_FEAT_TYPE_SCLP_CONF_CHAR,
     S390_FEAT_TYPE_SCLP_CONF_CHAR_EXT,
+    S390_FEAT_TYPE_SCLP_BYTE_134,
     S390_FEAT_TYPE_SCLP_CPU,
     S390_FEAT_TYPE_MISC,
     S390_FEAT_TYPE_PLO,
diff --git a/target/s390x/cpu_features_def.h b/target/s390x/cpu_features_def.h
index 5fc7e7b..d99da1d 100644
--- a/target/s390x/cpu_features_def.h
+++ b/target/s390x/cpu_features_def.h
@@ -109,6 +109,9 @@ typedef enum {
     S390_FEAT_SIE_PFMFI,
     S390_FEAT_SIE_IBS,
 
+    /* Read Info Byte 134 */
+    S390_FEAT_DIAG318,
+
     /* Sclp Cpu */
     S390_FEAT_SIE_F2,
     S390_FEAT_SIE_SKEY,
diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
index 70015ea..a3d1457 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -450,6 +450,7 @@ static uint16_t full_GEN12_GA1[] = {
     S390_FEAT_AP_QUERY_CONFIG_INFO,
     S390_FEAT_AP_FACILITIES_TEST,
     S390_FEAT_AP,
+    S390_FEAT_DIAG318,
 };
 
 static uint16_t full_GEN12_GA2[] = {
diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 2ebf26a..3915e36 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -2142,6 +2142,7 @@ static int kvm_to_feat[][2] = {
     { KVM_S390_VM_CPU_FEAT_PFMFI, S390_FEAT_SIE_PFMFI},
     { KVM_S390_VM_CPU_FEAT_SIGPIF, S390_FEAT_SIE_SIGPIF},
     { KVM_S390_VM_CPU_FEAT_KSS, S390_FEAT_SIE_KSS},
+    { KVM_S390_VM_CPU_FEAT_DIAG318, S390_FEAT_DIAG318},
 };
 
 static int query_cpu_feat(S390FeatBitmap features)
-- 
2.7.4