[libvirt] [PATCHv2 1/2] util, resctrl: using 64bit interface instead of 32bit for counters

[Wang Huaqiang]

The underlying resctrl monitoring is actually using 64 bit counters,
not the 32bit one. Correct this by using 64bit data type for reading
hardware value.

To keep the interface consistent, the result of CPU last level cache
that occupied by vcpu processors of specific restrl monitor group is
still reported with a truncated 32bit data type. because, in silicon
world, CPU cache size will never exceed 4GB.

Signed-off-by: Wang Huaqiang <huaqiang.wang at intel.com>
---
 src/qemu/qemu_driver.c | 15 +++++++++++++--
 src/util/virfile.c     | 40 ++++++++++++++++++++++++++++++++++++++++
 src/util/virfile.h     |  2 ++
 src/util/virresctrl.c  |  6 +++---
 src/util/virresctrl.h  |  2 +-
 5 files changed, 59 insertions(+), 6 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 7a7f388767..ad6f3130ae 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -20740,8 +20740,19 @@ qemuDomainGetStatsCpuCache(virQEMUDriverPtr driver,
                                          "cpu.cache.monitor.%zu.bank.%zu.id", i, j) < 0)
                 goto cleanup;
 
-            if (virTypedParamListAddUInt(params, resdata[i]->stats[j]->vals[0],
-                                         "cpu.cache.monitor.%zu.bank.%zu.bytes", i, j) < 0)
+            /* 'resdata[i]->stats[j]->vals[0]' keeps the value of how many last
+             * level cache in bank j currently occupied by the vcpus listed in
+             * resource monitor i, in bytes. This value is reported through a
+             * 64 bit hardware counter, so it is better to be arranged with
+             * data type in 64 bit width, but considering the fact that
+             * physical cache on a CPU could never be designed to be bigger
+             * than 4G bytes in size, to keep the 'domstats' interface
+             * historically consistent, it is safe to report the value with a
+             * truncated 'UInt' data type here. */
+            if (virTypedParamListAddUInt(params,
+                                         (unsigned int)resdata[i]->stats[j]->vals[0],
+                                         "cpu.cache.monitor.%zu.bank.%zu.bytes",
+                                         i, j) < 0)
                 goto cleanup;
         }
     }
diff --git a/src/util/virfile.c b/src/util/virfile.c
index 4fd865dd83..7bf33682c7 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -4196,6 +4196,46 @@ virFileReadValueUint(unsigned int *value, const char *format, ...)
 }
 
 
+/**
+ * virFileReadValueUllong:
+ * @value: pointer to unsigned long long to be filled in with the value
+ * @format, ...: file to read from
+ *
+ * Read unsigned int from @format and put it into @value.
+ *
+ * Return -2 for non-existing file, -1 on other errors and 0 if everything went
+ * fine.
+ */
+int
+virFileReadValueUllong(unsigned long long *value, const char *format, ...)
+{
+    g_autofree char *str = NULL;
+    g_autofree char *path = NULL;
+    va_list ap;
+
+    va_start(ap, format);
+    path = g_strdup_vprintf(format, ap);
+    va_end(ap);
+
+    if (!virFileExists(path))
+        return -2;
+
+    if (virFileReadAll(path, INT_BUFSIZE_BOUND(*value), &str) < 0)
+        return -1;
+
+    virStringTrimOptionalNewline(str);
+
+    if (virStrToLong_ullp(str, NULL, 10, value) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Invalid unsigned long long value '%s' in file '%s'"),
+                       str, path);
+        return -1;
+    }
+
+    return 0;
+}
+
+
 /**
  * virFileReadValueScaledInt:
  * @value: pointer to unsigned long long int to be filled in with the value
diff --git a/src/util/virfile.h b/src/util/virfile.h
index bcae40ee06..756c9a70b9 100644
--- a/src/util/virfile.h
+++ b/src/util/virfile.h
@@ -361,6 +361,8 @@ int virFileReadValueInt(int *value, const char *format, ...)
  G_GNUC_PRINTF(2, 3);
 int virFileReadValueUint(unsigned int *value, const char *format, ...)
  G_GNUC_PRINTF(2, 3);
+int virFileReadValueUllong(unsigned long long *value, const char *format, ...)
+ G_GNUC_PRINTF(2, 3);
 int virFileReadValueBitmap(virBitmapPtr *value, const char *format, ...)
  G_GNUC_PRINTF(2, 3);
 int virFileReadValueScaledInt(unsigned long long *value, const char *format, ...)
diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c
index b78fded026..684d2ce398 100644
--- a/src/util/virresctrl.c
+++ b/src/util/virresctrl.c
@@ -2678,7 +2678,7 @@ virResctrlMonitorGetStats(virResctrlMonitorPtr monitor,
     int rv = -1;
     int ret = -1;
     size_t i = 0;
-    unsigned int val = 0;
+    unsigned long long val = 0;
     DIR *dirp = NULL;
     char *datapath = NULL;
     char *filepath = NULL;
@@ -2734,8 +2734,8 @@ virResctrlMonitorGetStats(virResctrlMonitorPtr monitor,
             goto cleanup;
 
         for (i = 0; resources[i]; i++) {
-            rv = virFileReadValueUint(&val, "%s/%s/%s", datapath,
-                                      ent->d_name, resources[i]);
+            rv = virFileReadValueUllong(&val, "%s/%s/%s", datapath,
+                                        ent->d_name, resources[i]);
             if (rv == -2) {
                 virReportError(VIR_ERR_INTERNAL_ERROR,
                                _("File '%s/%s/%s' does not exist."),
diff --git a/src/util/virresctrl.h b/src/util/virresctrl.h
index 3dd7c96348..11f275acf4 100644
--- a/src/util/virresctrl.h
+++ b/src/util/virresctrl.h
@@ -204,7 +204,7 @@ struct _virResctrlMonitorStats {
     char **features;
     /* @vals store the statistical record values and @val[0] is the value for
      * @features[0], @val[1] for at features[1] ... respectively */
-    unsigned int *vals;
+    unsigned long long *vals;
     /* The length of @vals array */
     size_t nvals;
 };
-- 
2.23.0