From: Jiri Denemark <jdenemar@redhat.com>
Date: Thu, 30 May 2019 19:47:38 +0000 (+0200)
Subject: cpu_x86: Probe TSC frequency and scaling support
X-Git-Tag: v5.5.0-rc1~348
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ceb04d15e671b4fea1d674ee43c91410da9fe57d;p=thirdparty%2Flibvirt.git

cpu_x86: Probe TSC frequency and scaling support

When the host CPU supports invariant TSC the host CPU definition created
by virCPUx86GetHost will contain (unless probing fails for some reason)
addition TSC related data.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---

diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c
index cb03123787..689b6cdaf5 100644
--- a/src/cpu/cpu_x86.c
+++ b/src/cpu/cpu_x86.c
@@ -2762,6 +2762,15 @@ virCPUx86GetHost(virCPUDefPtr cpu,
     ret = x86DecodeCPUData(cpu, cpuData, models);
     cpu->microcodeVersion = virHostCPUGetMicrocodeVersion();
 
+    /* Probing for TSC frequency makes sense only if the CPU supports
+     * invariant TSC (Linux calls this constant_tsc in /proc/cpuinfo). */
+    if (virCPUx86DataCheckFeature(cpuData, "invtsc") == 1) {
+        VIR_DEBUG("Checking invariant TSC frequency");
+        cpu->tsc = virHostCPUGetTscInfo();
+    } else {
+        VIR_DEBUG("Host CPU does not support invariant TSC");
+    }
+
  cleanup:
     virCPUx86DataFree(cpuData);
     return ret;