[PATCH v2 2/3] util: Add virGetCpuHaltPollTime and virGetDebugFsKvmValue

[Yang Fei <yangfei85@xxxxxxxxxx>]

Add helper function virGetCpuHaltPollTime and virGetDebugFsKvmValue
to obtain the halt polling time. If system mount debugfs, and the
kernel support halt polling time statistic, it will work.

Signed-off-by: Yang Fei <yangfei85@xxxxxxxxxx>
---
 src/libvirt_private.syms |  2 ++
 src/util/virutil.c       | 78 ++++++++++++++++++++++++++++++++++++++++
 src/util/virutil.h       |  9 +++++
 3 files changed, 89 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 68e4b6aab8..f92213b8c2 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -3479,6 +3479,8 @@ virDoesUserExist;
 virDoubleToStr;
 virFormatIntDecimal;
 virFormatIntPretty;
+virGetCpuHaltPollTime;
+virGetDebugFsKvmValue;
 virGetDeviceID;
 virGetDeviceUnprivSGIO;
 virGetGroupID;
diff --git a/src/util/virutil.c b/src/util/virutil.c
index c0d25fe247..7e4531b4b4 100644
--- a/src/util/virutil.c
+++ b/src/util/virutil.c
@@ -1959,3 +1959,81 @@ virGetValueRaw(const char *path,
 
     return 0;
 }
+
+int
+virGetDebugFsKvmValue(struct dirent *ent,
+                    const char *path,
+                    const char *filename,
+                    unsigned long long *value)
+{
+    g_autofree char *valToStr = NULL;
+    g_autofree char *valPath = NULL;
+
+    valPath = g_strdup_printf("%s/%s/%s", path, ent->d_name, filename);
+
+    if (virGetValueRaw(valPath, &valToStr) < 0) {
+        return -1;
+    }
+
+    /* 10 is a Cardinality, must be between 2 and 36 inclusive,
+     * or special value 0. Used in fuction strtoull()
+     */
+    if (virStrToLong_ull(valToStr, NULL, 10, value) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Unable to parse '%s' as an integer"), valToStr);
+        return -1;
+    }
+
+    return 0;
+}
+
+int
+virGetCpuHaltPollTime(pid_t pid,
+                      unsigned long long *haltPollSuccess,
+                      unsigned long long *haltPollFail)
+{
+    g_autofree char *pidToStr = NULL;
+    g_autofree char *debugFsPath = NULL;
+    g_autofree char *completePath = NULL;
+    struct dirent *ent = NULL;
+    DIR *dir = NULL;
+    int ret = -1;
+    int flag = 0;
+
+    if (!(debugFsPath = virFileFindMountPoint("debugfs"))) {
+        virReportSystemError(errno, "%s",
+                             _("unable to find debugfs mountpoint"));
+        return ret;
+    }
+
+    completePath = g_strdup_printf("%s/%s", debugFsPath, "kvm");
+    if (virDirOpen(&dir, completePath) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       "%s %s", "Can not open directory", completePath);
+        return ret;
+    }
+
+    pidToStr = g_strdup_printf("%lld%c", (unsigned long long)pid, '-');
+    while (virDirRead(dir, &ent, NULL) > 0) {
+        if (STRPREFIX(ent->d_name, pidToStr)) {
+            flag = 1;
+            break;
+        }
+    }
+
+    if (flag == 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Could not find VM(Pid %s) in '%s'"), pidToStr, completePath);
+        goto cleanup;
+    }
+
+    if (virGetDebugFsKvmValue(ent, completePath, "halt_poll_success_ns", haltPollSuccess) < 0 ||
+        virGetDebugFsKvmValue(ent, completePath, "halt_poll_fail_ns", haltPollFail) < 0) {
+        goto cleanup;
+    }
+
+    ret = 0;
+cleanup:
+    closedir(dir);
+    return ret;
+}
diff --git a/src/util/virutil.h b/src/util/virutil.h
index 851b421476..00cef47208 100644
--- a/src/util/virutil.h
+++ b/src/util/virutil.h
@@ -228,3 +228,12 @@ int virPipeNonBlock(int fds[2]);
 
 int virGetValueRaw(const char *path,
                          char **value);
+
+int virGetDebugFsKvmValue(struct dirent *ent,
+                    const char *path,
+                    const char *filename,
+                    unsigned long long *value);
+
+int virGetCpuHaltPollTime(pid_t pid,
+                      unsigned long long *haltPollSuccess,
+                      unsigned long long *haltPollFail);
-- 
2.23.0