On 12/9/2022 2:55 PM, Chenyi Qiang wrote:
On 12/8/2022 2:25 PM, Xiaoyao Li wrote:
commit e37a5c7fa459 ("i386: Add Intel Processor Trace feature support")
added the support of Intel PT by making CPUID[14] of PT as fixed feature
set (from ICX) for any CPU model on any host. This truly breaks the PT
exposure on Intel SPR platform because SPR has less supported bitmap of
CPUID(0x14,1):EBX[15:0] than ICX.
To fix the problem, enable pass through of host's PT capabilities for
the cases "-cpu host/max" that it won't use default fixed PT feature set
of ICX but expand automatically based on get_supported_cpuid reported by
host. Meanwhile, it needs to ensure named CPU model still has the fixed
PT feature set to not break the live migration case of
"-cpu named_cpu_model,+intel-pt"
Introduces env->use_default_intel_pt flag.
- True means it's old CPU model that uses fixed PT feature set of ICX.
- False means the named CPU model has its own PT feature set.
Besides, to keep the same behavior for old CPU models that validate PT
feature set against default fixed PT feature set of ICX in addition to
validate from host's capabilities (via get_supported_cpuid) in
x86_cpu_filter_features().
In the future, new named CPU model, e.g., Sapphire Rapids, can define
its own PT feature set by setting @has_specific_intel_pt_feature_set to
It seems @has_specific_intel_pt_feature_set is not introduced in this
series. Then don't need to mention the specific flag name here.
Thanks for catching it.
It's leftover of previous version. I'll update the commit log for next
version.
true and defines it's own FEAT_14_0_EBX, FEAT_14_0_ECX, FEAT_14_1_EAX
and FEAT_14_1_EBX.
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
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