[Qemu-devel] [PATCH v13 2/5] i386: Introduce auto_topoext bit to manage topoext

[Babu Moger]

Introduce the auto_topoext bit to to control topoext feature.

Also add new field auto_topoext(in X86CPUDefinition). This will
be used to enable topoext on newer CPU models where topoext can
be supported.

Signed-off-by: Babu Moger <address@hidden>
---
 include/hw/i386/pc.h |  4 ++++
 target/i386/cpu.c    | 12 ++++++++++++
 target/i386/cpu.h    |  5 +++++
 3 files changed, 21 insertions(+)

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 04d1f8c..cc30ec3 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -303,6 +303,10 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
         .driver   = TYPE_X86_CPU,\
         .property = "legacy-cache",\
         .value    = "on",\
+    },{\
+        .driver   = TYPE_X86_CPU,\
+        .property = "auto-topoext",\
+        .value    = "off",\
     },
 
 #define PC_COMPAT_2_11 \
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 86fb1a4..d3411ed 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1283,6 +1283,8 @@ struct X86CPUDefinition {
     FeatureWordArray features;
     const char *model_id;
     CPUCaches *cache_info;
+    /* Set it if topoext can be enabled in CPU models */
+    int auto_topoext;
 };
 
 static CPUCaches epyc_cache_info = {
@@ -3517,6 +3519,9 @@ static void x86_cpu_load_def(X86CPU *cpu, 
X86CPUDefinition *def, Error **errp)
     /* legacy-cache defaults to 'off' if CPU model provides cache info */
     cpu->legacy_cache = !def->cache_info;
 
+    /* Set auto_topoext if both machine property and CPU model supports it */
+    cpu->auto_topoext =  cpu->auto_topoext & def->auto_topoext;
+
     /* Special cases not set in the X86CPUDefinition structs: */
     /* TODO: in-kernel irqchip for hvf */
     if (kvm_enabled()) {
@@ -5382,6 +5387,13 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_BOOL("legacy-cache", X86CPU, legacy_cache, true),
 
     /*
+     * auto-topoext property will be used to enable topoext feature.
+     * This will be disabled on all the older CPU models. Will be
+     * enabled on newer CPU modeles which can support topology extention.
+     */
+     DEFINE_PROP_BOOL("auto-topoext", X86CPU, auto_topoext, false),
+
+    /*
      * From "Requirements for Implementing the Microsoft
      * Hypervisor Interface":
      * 
https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 89c82be..8783d36 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1409,6 +1409,11 @@ struct X86CPU {
      */
     bool legacy_cache;
 
+    /* Compatibility bits to enable topoext feature on all newer machines
+     * Disabled on older machines. Enabled on newer CPU models
+     */
+    bool auto_topoext;
+
     /* Compatibility bits for old machine types: */
     bool enable_cpuid_0xb;
 
-- 
1.8.3.1