[Qemu-devel] [RFC 11/28] s390x/cpumodel: check and apply the CPU model

[David Hildenbrand <dahi@linux.vnet.ibm.com>]

We have to test if a configured CPU model is runnable in the current
configuration, and if not report why that is the case. This is done by
comparing it to the maximum supported model (host for KVM or z900 for TCG).
Also, we want to do some base sanity checking for a configured CPU model.

We'll cache the maximum model and the applied model (for performance
reasons and because KVM can only be configured before any VCPU is created).

For unavailable "host" model, we have to make sure that we inform KVM,
so it can do some compatibility stuff (enable CMMA later on to be precise).

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
---
 target-s390x/cpu_models.c | 154 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)

diff --git a/target-s390x/cpu_models.c b/target-s390x/cpu_models.c
index 7e3f544..e7bcea9 100644
--- a/target-s390x/cpu_models.c
+++ b/target-s390x/cpu_models.c
@@ -15,6 +15,7 @@
 #include "gen-features.h"
 #include "qapi/error.h"
 #include "qapi/visitor.h"
+#include "qemu/error-report.h"
 #ifndef CONFIG_USER_ONLY
 #include "sysemu/arch_init.h"
 #endif
@@ -170,14 +171,167 @@ CpuDefinitionInfoList *arch_query_cpu_definitions(Error **errp)
 }
 #endif
 
+static void check_consistency(const S390CPUModel *model)
+{
+    static int dep[][2] = {
+        { S390_FEAT_IPTE_RANGE, S390_FEAT_DAT_ENH_1 },
+        { S390_FEAT_IDTE_SEGMENT, S390_FEAT_DAT_ENH_1 },
+        { S390_FEAT_IDTE_REGION, S390_FEAT_DAT_ENH_1 },
+        { S390_FEAT_IDTE_REGION, S390_FEAT_IDTE_SEGMENT },
+        { S390_FEAT_LOCAL_TLB_CLEARING, S390_FEAT_DAT_ENH_1},
+        { S390_FEAT_LONG_DISPLACEMENT_FAST, S390_FEAT_LONG_DISPLACEMENT },
+        { S390_FEAT_DFP_FAST, S390_FEAT_DFP },
+        { S390_FEAT_TRANSACTIONAL_EXE, S390_FEAT_GEN12_ENH },
+        { S390_FEAT_CONSTRAINT_TRANSACTIONAL_EXE, S390_FEAT_TRANSACTIONAL_EXE },
+        { S390_FEAT_EDAT_2, S390_FEAT_EDAT_1},
+        { S390_FEAT_MSA_EXT_5, S390_FEAT_KIMD_SHA_512 },
+        { S390_FEAT_MSA_EXT_5, S390_FEAT_KLMD_SHA_512 },
+        { S390_FEAT_MSA_EXT_4, S390_FEAT_MSA_EXT_3 },
+        { S390_FEAT_SIE_CMMA, S390_FEAT_CMM },
+        { S390_FEAT_SIE_CMMA, S390_FEAT_SIE_GSLS },
+        { S390_FEAT_SIE_PFMFI, S390_FEAT_EDAT_1 },
+    };
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(dep); i++) {
+        if (test_bit(dep[i][0], model->features) &&
+            !test_bit(dep[i][1], model->features)) {
+            error_report("Warning: \'%s\' requires \'%s\'.",
+                         s390_feat_def(dep[i][0])->name,
+                         s390_feat_def(dep[i][1])->name);
+        }
+    }
+}
+
+static void error_prepend_missing_feat(const char *name, void *opaque)
+{
+    error_prepend((Error **) opaque, "%s ", name);
+}
+
+static void check_compatibility(const S390CPUModel *max_model,
+                                const S390CPUModel *model, Error **errp)
+{
+    S390FeatBitmap missing;
+
+    if (model->def->gen > max_model->def->gen) {
+        error_setg(errp, "Selected CPU generation is too new. Maximum "
+                   "supported model in the configuration: \'%s\'",
+                   max_model->def->name);
+        return;
+    } else if (model->def->gen == max_model->def->gen &&
+               model->def->ec_ga > max_model->def->ec_ga) {
+        error_setg(errp, "Selected CPU GA level is too new. Maximum "
+                   "supported model in the configuration: \'%s\'",
+                   max_model->def->name);
+        return;
+    }
+
+    /* detect the missing features to properly report them */
+    bitmap_andnot(missing, model->features, max_model->features, S390_FEAT_MAX);
+    if (bitmap_empty(missing, S390_FEAT_MAX)) {
+        return;
+    }
+
+    error_setg(errp, " ");
+    s390_feat_bitmap_to_ascii(missing, errp, error_prepend_missing_feat);
+    error_prepend(errp, "Some features requested in the CPU model are not "
+                  "available in the configuration: ");
+}
+
+static S390CPUModel *get_max_cpu_model(Error **errp)
+{
+#ifndef CONFIG_USER_ONLY
+    static S390CPUModel max_model;
+    static bool cached;
+
+    if (cached) {
+        return &max_model;
+    }
+
+    if (kvm_enabled()) {
+        error_setg(errp, "KVM does not support CPU models.");
+    } else {
+        /* TCG enulates a z900 */
+        max_model.def = &s390_cpu_defs[0];
+        bitmap_copy(max_model.features, max_model.def->default_feat,
+                    S390_FEAT_MAX);
+    }
+    if (!*errp) {
+        cached = true;
+        return &max_model;
+    }
+#endif
+    return NULL;
+}
+
+static inline void apply_cpu_model(const S390CPUModel *model, Error **errp)
+{
+#ifndef CONFIG_USER_ONLY
+    static S390CPUModel applied_model;
+    static bool applied;
+
+    /*
+     * We have the same model for all VCPUs. KVM can only be configured before
+     * any VCPUs are defined in KVM.
+     */
+    if (applied) {
+        if (model && memcmp(&applied_model, model, sizeof(S390CPUModel))) {
+            error_setg(errp, "Mixed CPU models are not supported on s390x.");
+        }
+        return;
+    }
+
+    if (kvm_enabled()) {
+        /* FIXME KVM */
+        error_setg(errp, "KVM doesn't support CPU models.");
+    } else if (model) {
+        /* FIXME TCG - use data for stdip/stfl */
+    }
+
+    if (!*errp) {
+        applied = true;
+        if (model) {
+            applied_model = *model;
+        }
+    }
+#endif
+}
+
 void s390_realize_cpu_model(CPUState *cs, Error **errp)
 {
     S390CPUClass *xcc = S390_CPU_GET_CLASS(cs);
+    S390CPU *cpu = S390_CPU(cs);
+    const S390CPUModel *max_model;
 
     if (xcc->kvm_required && !kvm_enabled()) {
         error_setg(errp, "CPU definition requires KVM");
         return;
     }
+
+    if (!cpu->model) {
+        /* no host model support -> perform compatibility stuff */
+        apply_cpu_model(NULL, errp);
+        return;
+    }
+
+    max_model = get_max_cpu_model(errp);
+    if (*errp) {
+        error_prepend(errp, "CPU models are not available: ");
+        return;
+    }
+
+    /* copy over properties that can vary */
+    cpu->model->lowest_ibc = max_model->lowest_ibc;
+    cpu->model->cpu_id = max_model->cpu_id;
+    cpu->model->cpu_ver = max_model->cpu_ver;
+
+    check_consistency(cpu->model);
+    check_compatibility(max_model, cpu->model, errp);
+    if (*errp) {
+        return;
+    }
+
+    apply_cpu_model(cpu->model, errp);
 }
 
 static void get_feature(Object *obj, Visitor *v, const char *name,
-- 
2.6.6