[PATCH v2] i386/cpu: Make the Intel PT LIP feature configurable

[Luwei Kang]

The current implementation will disable the guest Intel PT feature
if the Intel PT LIP feature is supported on the host, but the LIP
feature is comming soon(e.g. SnowRidge and later).

This patch will make the guest LIP feature configurable and Intel
PT feature can be enabled in guest when the guest LIP status same
with the host.

Signed-off-by: Luwei Kang <luwei.kang@intel.com>
Message-Id: <20201014080443.23751-2-luwei.kang@intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
v1->v2:
    Add a dependency on the Intel PT flag.

    Test on SnowRidge Server(HW support LIP feature)：
    1. "-cpu host" : Intel PT enabled in guest;
    2. "-cpu Snowridge" : Intel PT disabled in guest because
       Intel PT is disabled by default;
    3. "-cpu Snowridge,+intel-pt" : Intel PT disabled in
       guest(Host LIP different from guest)
    4. "-cpu Snowridge,+intel-pt,+intel-pt-lip" : Intel PT enabled
       in guest(Host LIP same with guest)
    5. "-cpu Snowridge,+intel-pt-lip" : Intel PT disabled in guest
       and output:
       warning: This feature depends on other features that were
       not requested: CPUID.14H:ECX.intel-pt-lip [bit 31]

    Test on IceLake Server(HW don't support LIP feature)：
    1. "-cpu host" : Intel PT enabled in guest;
    2. "-cpu Icelake-Server" : Intel PT disabled in guest because
       Intel PT is disabled by default;
    3. "-cpu Icelake-Server,+intel-pt" : Intel PT enabled in
       guest(Host LIP same with guest)
    4. "-cpu Icelake-Server,+intel-pt,+intel-pt-lip" : Intel PT
       disabled in guest(Host LIP different from guest)

---
 target/i386/cpu.c | 31 ++++++++++++++++++++++++++++++-
 target/i386/cpu.h |  4 ++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 5a8c96072e..900ea08283 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -672,6 +672,7 @@ static void x86_cpu_vendor_words2str(char *dst, uint32_t 
vendor1,
 #define TCG_XSAVE_FEATURES (CPUID_XSAVE_XSAVEOPT | CPUID_XSAVE_XGETBV1)
           /* missing:
           CPUID_XSAVE_XSAVEC, CPUID_XSAVE_XSAVES */
+#define TCG_14_0_ECX_FEATURES 0
 
 typedef enum FeatureWordType {
    CPUID_FEATURE_WORD,
@@ -1301,6 +1302,26 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] 
= {
         }
     },
 
+    [FEAT_14_0_ECX] = {
+        .type = CPUID_FEATURE_WORD,
+        .feat_names = {
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, "intel-pt-lip",
+        },
+        .cpuid = {
+            .eax = 0x14,
+            .needs_ecx = true, .ecx = 0,
+            .reg = R_ECX,
+        },
+        .tcg_features = TCG_14_0_ECX_FEATURES,
+     },
+
 };
 
 typedef struct FeatureMask {
@@ -1373,6 +1394,10 @@ static FeatureDep feature_dependencies[] = {
         .from = { FEAT_7_0_EBX,             CPUID_7_0_EBX_RDSEED },
         .to = { FEAT_VMX_SECONDARY_CTLS,    VMX_SECONDARY_EXEC_RDSEED_EXITING 
},
     },
+    {
+        .from = { FEAT_7_0_EBX,             CPUID_7_0_EBX_INTEL_PT },
+        .to = { FEAT_14_0_ECX,              ~0ull },
+    },
     {
         .from = { FEAT_8000_0001_EDX,       CPUID_EXT2_RDTSCP },
         .to = { FEAT_VMX_SECONDARY_CTLS,    VMX_SECONDARY_EXEC_RDTSCP },
@@ -5752,6 +5777,9 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
uint32_t count,
             *eax = INTEL_PT_MAX_SUBLEAF;
             *ebx = INTEL_PT_MINIMAL_EBX;
             *ecx = INTEL_PT_MINIMAL_ECX;
+            if (env->features[FEAT_14_0_ECX] & CPUID_14_0_ECX_LIP) {
+                *ecx |= CPUID_14_0_ECX_LIP;
+            }
         } else if (count == 1) {
             *eax = INTEL_PT_MTC_BITMAP | INTEL_PT_ADDR_RANGES_NUM;
             *ebx = INTEL_PT_PSB_BITMAP | INTEL_PT_CYCLE_BITMAP;
@@ -6498,7 +6526,8 @@ static void x86_cpu_filter_features(X86CPU *cpu, bool 
verbose)
                                            INTEL_PT_ADDR_RANGES_NUM) ||
            ((ebx_1 & (INTEL_PT_PSB_BITMAP | INTEL_PT_CYCLE_BITMAP)) !=
                 (INTEL_PT_PSB_BITMAP | INTEL_PT_CYCLE_BITMAP)) ||
-           (ecx_0 & INTEL_PT_IP_LIP)) {
+           ((ecx_0 & CPUID_14_0_ECX_LIP) !=
+                (env->features[FEAT_14_0_ECX] & CPUID_14_0_ECX_LIP))) {
             /*
              * Processor Trace capabilities aren't configurable, so if the
              * host can't emulate the capabilities we report on
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 88e8586f8f..c4a49c06a8 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -541,6 +541,7 @@ typedef enum FeatureWord {
     FEAT_VMX_EPT_VPID_CAPS,
     FEAT_VMX_BASIC,
     FEAT_VMX_VMFUNC,
+    FEAT_14_0_ECX,
     FEATURE_WORDS,
 } FeatureWord;
 
@@ -797,6 +798,9 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
 /* AVX512 BFloat16 Instruction */
 #define CPUID_7_1_EAX_AVX512_BF16       (1U << 5)
 
+/* Packets which contain IP payload have LIP values */
+#define CPUID_14_0_ECX_LIP              (1U << 31)
+
 /* CLZERO instruction */
 #define CPUID_8000_0008_EBX_CLZERO      (1U << 0)
 /* Always save/restore FP error pointers */
-- 
2.18.4