[PATCH v3 2/2] x86/resctrl: Remove hard-coded memory bandwidth event configuration

[Babu Moger]

If the BMEC (Bandwidth Monitoring Event Configuration) feature is
supported, the bandwidth events can be configured. The maximum supported
bandwidth bitmask can be determined by following CPUID command.

CPUID_Fn80000020_ECX_x03 [Platform QoS Monitoring Bandwidth Event
Configuration] Read-only. Reset: 0000_007Fh.
Bits    Description
31:7    Reserved
 6:0    Identifies the bandwidth sources that can be tracked.

The bandwidth sources can change with the processor generations.
Remove the hard-coded value and detect using CPUID command. Also,
print the valid bitmask when the user tries to configure invalid value.

The CPUID details are documentation in the PPR listed below [1].
[1] Processor Programming Reference (PPR) Vol 1.1 for AMD Family 19h Model
11h B1 - 55901 Rev 0.25.

Fixes: dc2a3e857981 ("x86/resctrl: Add interface to read mbm_total_bytes_config")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v3: Changed the event_mask name to mbm_cfg_mask. Added comments about the field.
    Reverted the masking of event configuration to original code.
    Few minor comment changes.

v2: Earlier sent as a part of ABMC feature.
    https://lore.kernel.org/lkml/20231201005720.235639-1-babu.moger@xxxxxxx/
    But this is not related to ABMC. Sending it separate now.
    Removed the global resctrl_max_evt_bitmask. Added event_mask as part of
    the resource.
---
 arch/x86/kernel/cpu/resctrl/internal.h | 3 +++
 arch/x86/kernel/cpu/resctrl/monitor.c  | 6 ++++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 6 ++++--
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index d2979748fae4..e3dc35a00a19 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -394,6 +394,8 @@ struct rdt_parse_data {
  * @msr_update:		Function pointer to update QOS MSRs
  * @mon_scale:		cqm counter * mon_scale = occupancy in bytes
  * @mbm_width:		Monitor width, to detect and correct for overflow.
+ * @mbm_cfg_mask:	Bandwidth sources that can be tracked when Bandwidth
+ *			Monitoring Event Configuration (BMEC) is supported.
  * @cdp_enabled:	CDP state of this resource
  *
  * Members of this structure are either private to the architecture
@@ -408,6 +410,7 @@ struct rdt_hw_resource {
 				 struct rdt_resource *r);
 	unsigned int		mon_scale;
 	unsigned int		mbm_width;
+	unsigned int		mbm_cfg_mask;
 	bool			cdp_enabled;
 };
 
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index f136ac046851..acca577e2b06 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -813,6 +813,12 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 		return ret;
 
 	if (rdt_cpu_has(X86_FEATURE_BMEC)) {
+		u32 eax, ebx, ecx, edx;
+
+		/* Detect list of bandwidth sources that can be tracked */
+		cpuid_count(0x80000020, 3, &eax, &ebx, &ecx, &edx);
+		hw_res->mbm_cfg_mask = ecx & MAX_EVT_CONFIG_BITS;
+
 		if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
 			mbm_total_event.configurable = true;
 			mbm_config_rftype_init("mbm_total_bytes_config");
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 69a1de92384a..5b5a8f0ffb2f 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1617,12 +1617,14 @@ static void mon_event_config_write(void *info)
 static int mbm_config_write_domain(struct rdt_resource *r,
 				   struct rdt_domain *d, u32 evtid, u32 val)
 {
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 	struct mon_config_info mon_info = {0};
 	int ret = 0;
 
 	/* mon_config cannot be more than the supported set of events */
-	if (val > MAX_EVT_CONFIG_BITS) {
-		rdt_last_cmd_puts("Invalid event configuration\n");
+	if ((val & hw_res->mbm_cfg_mask) != val) {
+		rdt_last_cmd_printf("Invalid input: The maximum valid bitmask is 0x%02x\n",
+				    hw_res->mbm_cfg_mask);
 		return -EINVAL;
 	}
 
-- 
2.34.1