[PATCH v1 06/10] capabilities: Expose NUMA memory side cache

[Martin Kletzander]

On Mon, May 31, 2021 at 10:36:07AM +0200, Michal Privoznik wrote:
>Memory on a NUMA node can have a side caches. Configuring these
>for a domain was implemented in v6.6.0-rc1~249 and friends.
>However, up until now mgmt applications did not really know what
>values to pass because we were not exposing caches of the host.
>With recent enough kernel these are exposed under sysfs and with
>a bit of parsing we can extend our capabilities XML. The sysfs
>structure is documented in kernel's
>Documentation/admin-guide/mm/numaperf.rst and basically maps in
>1:1 fashion to our virNumaCache structure.
>
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
> docs/schemas/capability.rng    |   4 +
> src/conf/capabilities.c        | 149 ++++++++++++++++++++++++++++++++-
> src/conf/capabilities.h        |   4 +-
> src/libxl/libxl_capabilities.c |   3 +-
> src/test/test_driver.c         |   3 +-
> tests/testutils.c              |   3 +-
> 6 files changed, 158 insertions(+), 8 deletions(-)
>
>diff --git a/src/conf/capabilities.c b/src/conf/capabilities.c
>index 9332daf6a6..7b60676070 100644
>--- a/src/conf/capabilities.c
>+++ b/src/conf/capabilities.c
>@@ -1535,6 +1547,129 @@ virCapabilitiesGetNUMAPagesInfo(int node,
> }
>
>
>+static int
>+virCapabilitiesGetNodeCacheReadFile(const char *prefix,
>+                                    const char *dir,
>+                                    const char *file,
>+                                    unsigned int *value)
>+{
>+    g_autofree char *path = gstrdup_printf("%s/%s/%s", prefix, dir, file);

Use g_build_filename() instead.

As a side note, I also wonder if there is an easier and consistent way
that can also handle things like "%s/something%s/%s" etc., but one
temporary autofree variable is probably fine.

>+    int rv = virFileReadValueUint(value, "%s", path);
>+

This clearly shows that my (pre-glib) ideas for virFileReadValue*()
functions were overcomplicated and the functions should just take path
without a format, especially when we now have g_autofree,
g_build_filename() and others.  That's just a thought, unrelated to your
series, though.
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