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[RFC,4/6] target/i386: Add support for Intel Thread Director feature

Message ID 20240203093054.412135-5-zhao1.liu@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series Intel Thread Director Virtualization Support in QEMU | expand

Commit Message

Zhao Liu Feb. 3, 2024, 9:30 a.m. UTC 
From: Zhao Liu <zhao1.liu@intel.com>

Intel Thread Director (ITD) is the extension of HFI, and it extends
the HFI to provide performance and energy efficiency data for advanced
classes of instructions [1].

From Alder Lake, Intel's client products support ITD, and this feature
can be used in VM to optimize scheduling on hybrid architectures.

Like HFI, ITD virtualization also has the same topology limitations
(only 1 die and 1 socket) because ITD's virtualization support is based
on HFI.

In order to avoid potential contention problems caused by multiple
virtual-packages/dies, add the following restrictions to the ITD feature
bit:

1. Mark ITD as no_autoenable_flags and it won't be enabled by default.
2. ITD can't be enabled for the case with multiple packages/dies.

ITD feature depends on HFI, so also add its dependency.

[1]: SDM, vol. 3B, section 15.6 HARDWARE FEEDBACK INTERFACE AND INTEL
     THREAD DIRECTOR

Tested-by: Yanting Jiang <yanting.jiang@intel.com>
Co-developed-by: Zhuocheng Ding <zhuocheng.ding@intel.com>
Signed-off-by: Zhuocheng Ding <zhuocheng.ding@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 target/i386/cpu.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)
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Patch

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index e3eb361436c9..55287d0a3e73 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1118,17 +1118,18 @@  FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, "hfi",
-            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, "itd",
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
         },
         .cpuid = { .eax = 6, .reg = R_EAX, },
         .tcg_features = TCG_6_EAX_FEATURES,
         /*
-         * PTS and HFI shouldn't be enabled by default since they have
+         * PTS, HFI and ITD shouldn't be enabled by default since they have
          * requirement for cpu topology.
          */
-        .no_autoenable_flags = CPUID_6_EAX_PTS | CPUID_6_EAX_HFI,
+        .no_autoenable_flags = CPUID_6_EAX_PTS | CPUID_6_EAX_HFI |
+                               CPUID_6_EAX_ITD,
     },
     [FEAT_XSAVE_XCR0_LO] = {
         .type = CPUID_FEATURE_WORD,
@@ -1569,6 +1570,10 @@  static FeatureDep feature_dependencies[] = {
         .from = { FEAT_6_EAX,               CPUID_6_EAX_PTS },
         .to = { FEAT_6_EAX,                 CPUID_6_EAX_HFI },
     },
+    {
+        .from = { FEAT_6_EAX,               CPUID_6_EAX_HFI },
+        .to = { FEAT_6_EAX,                 CPUID_6_EAX_ITD },
+    },
 };
 
 typedef struct X86RegisterInfo32 {
@@ -7468,10 +7473,10 @@  static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
         return;
     }
 
-    if (env->features[FEAT_6_EAX] & CPUID_6_EAX_HFI &&
+    if (env->features[FEAT_6_EAX] & (CPUID_6_EAX_HFI | CPUID_6_EAX_ITD) &&
         (ms->smp.dies > 1 || ms->smp.sockets > 1)) {
         error_setg(errp,
-                   "HFI currently only supports die/package, "
+                   "HFI/ITD currently only supports die/package, "
                    "please set by \"-smp ...,sockets=1,dies=1\"");
         return;
     }