x86/resctrl: Switch over to the resctrl mbps_val list

Updates to resctrl's software controller follow the same path as
other configuration updates, but they don't modify the hardware state.
rdtgroup_schemata_write() uses parse_line() and the resource's
parse_ctrlval() function to stage the configuration.
resctrl_arch_update_domains() then updates the mbps_val[] array
instead, and resctrl_arch_update_domains() skips the rdt_ctrl_update()
call that would update hardware.

This complicates the interface between resctrl's filesystem parts
and architecture specific code. It should be possible for mba_sc
to be completely implemented by the filesystem parts of resctrl. This
would allow it to work on a second architecture with no additional code.
resctrl_arch_update_domains() using the mbps_val[] array prevents this.

Change parse_bw() to write the configuration value directly to the
mbps_val[] array in the domain structure. Change rdtgroup_schemata_write()
to skip the call to resctrl_arch_update_domains(), meaning all the
mba_sc specific code in resctrl_arch_update_domains() can be removed.
On the read-side, show_doms() and update_mba_bw() are changed to read
the mbps_val[] array from the domain structure. With this,
resctrl_arch_get_config() no longer needs to consider mba_sc resources.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jamie Iles <quic_jiles@quicinc.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Xin Hao <xhao@linux.alibaba.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20220902154829.30399-10-james.morse@arm.com

1 files changed, 4 insertions, 6 deletions

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 497cadf3285d..16028b2f756a 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -447,13 +447,11 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
 	hw_dom_mba = resctrl_to_arch_dom(dom_mba);
 
 	cur_bw = pmbm_data->prev_bw;
-	user_bw = resctrl_arch_get_config(r_mba, dom_mba, closid, CDP_NONE);
+	user_bw = dom_mba->mbps_val[closid];
 	delta_bw = pmbm_data->delta_bw;
-	/*
-	 * resctrl_arch_get_config() chooses the mbps/ctrl value to return
-	 * based on is_mba_sc(). For now, reach into the hw_dom.
-	 */
-	cur_msr_val = hw_dom_mba->ctrl_val[closid];
+
+	/* MBA resource doesn't support CDP */
+	cur_msr_val = resctrl_arch_get_config(r_mba, dom_mba, closid, CDP_NONE);
 
 	/*
 	 * For Ctrl groups read data from child monitor groups.