x86/resctrl: Add a helper to read a closid's configuration

x86/resctrl: Add a helper to read a closid's configuration

Functions like show_doms() reach into the architecture's private
structure to retrieve the configuration from the struct rdt_hw_resource.

The hardware configuration may look completely different to the
values resctrl gets from user-space. The staged configuration and
resctrl_arch_update_domains() allow the architecture to convert or
translate these values.

Resctrl shouldn't read or write the ctrl_val[] values directly. Add
a helper to read the current configuration. This will allow another
architecture to scale the bitmaps if necessary, and possibly use
controls that don't take the user-space control format at all.

Of the remaining functions that access ctrl_val[] directly,
apply_config() is part of the architecture-specific code, and is
called via resctrl_arch_update_domains(). reset_all_ctrls() will be an
architecture specific helper.

update_mba_bw() manipulates both ctrl_val[], mbps_val[] and the
hardware. The mbps_val[] that matches the mba_sc state of the resource
is changed, but the other is left unchanged. Abstracting this is the
subject of later patches that affect set_mba_sc() too.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jamie Iles <jamie@nuviainc.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lkml.kernel.org/r/20210728170637.25610-17-james.morse@arm.com