x86/resctrl: Make resctrl_mounted checks explicit

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T2RT

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/log/?h=mpam/snapshot/v6.7-rc2



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The rdt_enable_key is switched when resctrl is mounted, and used to
prevent a second mount of the filesystem. It also enables the
architecture's context switch code.

This requires another architecture to have the same set of static-keys,
as resctrl depends on them too. The existing users of these static-keys
are implicitly also checking if the filesystem is mounted.

Make the resctrl_mounted checks explicit: resctrl can keep track of
whether it has been mounted once. This doesn't need to be combined with
whether the arch code is context switching the CLOSID.

rdt_mon_enable_key is never used just to test that resctrl is mounted,
but does also have this implication. Add a resctrl_mounted to all uses
of rdt_mon_enable_key.

This will allow the static-key changing to be moved behind resctrl_arch_
calls.

Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Zeng Heng <zengheng4@huawei.com>