qemu: Don't cache domCaps in virQEMUDriverGetDomainCapabilities()

Currently, whenever a domain capabilities is needed (fortunately,
after cleanup done by previous commits it is now only in
virConnectGetDomainCapabilities()), the object is stored in a
cache. But there is no invalidation mechanism for the cache
(except the implicit one - the cache is part of qemuCaps and thus
share its lifetime, but that is not enough). Therefore, if
something changes - for instance new firmware files are
installed, or old are removed these changes are not reflected in
the virConnectGetDomainCapabilities() output.

Originally, the caching was there because domCaps were used
during device XML validation and they were used a lot from our
test suite. But this is no longer the case. And therefore, we
don't need the cache and can construct fresh domCaps on each
virConnectGetDomainCapabilities() call.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1807198

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 6993ff179f49c4e0a2cc493923cbffd1e58b1a82..80ff18204eb0c16ef335705722866dd7b04740a1 100644 (file)
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -1428,11 +1428,8 @@ virCapsPtr virQEMUDriverGetCapabilities(virQEMUDriverPtr driver,
 /**
  * virQEMUDriverGetDomainCapabilities:
  *
- * Get a reference to the virDomainCapsPtr instance from the virQEMUCapsPtr
- * domCapsCache. If there's no domcaps in the cache, create a new instance,
- * add it to the cache, and return a reference.
- *
- * The caller must release the reference with virObjetUnref
+ * Get a reference to the virDomainCapsPtr instance. The caller
+ * must release the reference with virObjetUnref().
  *
  * Returns: a reference to a virDomainCapsPtr instance or NULL
  */
@@ -1444,15 +1441,19 @@ virQEMUDriverGetDomainCapabilities(virQEMUDriverPtr driver,
                                    virDomainVirtType virttype)
 {
     g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+    g_autoptr(virDomainCaps) domCaps = NULL;
+    const char *path = virQEMUCapsGetBinary(qemuCaps);
+
+    if (!(domCaps = virDomainCapsNew(path, machine, arch, virttype)))
+        return NULL;
+
+    if (virQEMUCapsFillDomainCaps(qemuCaps, driver->hostarch,
+                                  domCaps, driver->privileged,
+                                  cfg->firmwares,
+                                  cfg->nfirmwares) < 0)
+        return NULL;
 
-    return virQEMUCapsGetDomainCapsCache(qemuCaps,
-                                         machine,
-                                         arch,
-                                         virttype,
-                                         driver->hostarch,
-                                         driver->privileged,
-                                         cfg->firmwares,
-                                         cfg->nfirmwares);
+    return g_steal_pointer(&domCaps);
 }