[PATCH v1 Resend] target/i386: set the CPUID level to 0x14 on old machine-type

[Luwei Kang <luwei.kang@intel.com>]

The CPUID level need to be set to 0x14 manually on old
machine-type if Intel PT is enabled in guest. e.g. in Qemu 3.1
-machine pc-i440fx-3.1 -cpu qemu64,+intel-pt
will be CPUID[0].EAX(level)=7 and CPUID[7].EBX[25](intel-pt)=1.

Some Intel PT capabilities are exposed by leaf 0x14 and the
missing capabilities will cause some MSRs access failed.
This patch add a warning message to inform the user to extend
the CPUID level.

Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Luwei Kang <luwei.kang@intel.com>
---
 target/i386/cpu.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index a624163..f67c479 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5440,8 +5440,12 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
 
         /* Intel Processor Trace requires CPUID[0x14] */
         if ((env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_INTEL_PT) &&
-             kvm_enabled() && cpu->intel_pt_auto_level) {
-            x86_cpu_adjust_level(cpu, &cpu->env.cpuid_min_level, 0x14);
+             kvm_enabled()) {
+            if (cpu->intel_pt_auto_level)
+                x86_cpu_adjust_level(cpu, &cpu->env.cpuid_min_level, 0x14);
+            else
+                warn_report("Intel PT need CPUID leaf 0x14, please set "
+                            "by \"-cpu ...,+intel-pt,level=0x14\"");
         }
 
         /* CPU topology with multi-dies support requires CPUID[0x1F] */
-- 
1.8.3.1