[PATCH v2 04/17] x86/resctrl: Detect Assignable Bandwidth Monitoring feature details

[Babu Moger]

ABMC feature details are reported via CPUID Fn8000_0020_EBX_x5.
Bits Description
15:0 MAX_ABMC Maximum Supported Assignable Bandwidth
     Monitoring Counter ID + 1

Detect the feature details and update
/sys/fs/resctrl/info/L3_MON/mon_features.

If the system supports Assignable Bandwidth Monitoring Counters (ABMC),
the output will have additional text.
 $ cat /sys/fs/resctrl/info/L3_MON/mon_features
   mbm_assign_capable

The feature details are documented in APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming
Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth
Monitoring (ABMC).

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537

---
v2: Changed the field name to mbm_assign_capable from abmc_capable.
---
 Documentation/arch/x86/resctrl.rst     |  7 +++++++
 arch/x86/kernel/cpu/resctrl/core.c     | 17 +++++++++++++++++
 arch/x86/kernel/cpu/resctrl/internal.h |  3 +++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |  3 +++
 include/linux/resctrl.h                |  2 ++
 5 files changed, 32 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index d816ded93c22..ecc6c65bdaca 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -197,6 +197,13 @@ with the following files:
 			mbm_local_bytes
 			mbm_local_bytes_config
 
+		If the system supports Assignable Bandwidth Monitoring
+		Counters (ABMC), the output will have additional text.
+		Example::
+
+			# cat /sys/fs/resctrl/info/L3_MON/mon_features
+			mbm_assign_capable
+
 "mbm_total_bytes_config", "mbm_local_bytes_config":
 	Read/write files containing the configuration for the mbm_total_bytes
 	and mbm_local_bytes events, respectively, when the Bandwidth
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 4efe2d6a9eb7..f40ee271a5c7 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -303,6 +303,17 @@ static void rdt_get_cdp_l2_config(void)
 	rdt_get_cdp_config(RDT_RESOURCE_L2);
 }
 
+static void rdt_get_abmc_cfg(struct rdt_resource *r)
+{
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+	u32 eax, ebx, ecx, edx;
+
+	r->mbm_assign_capable = true;
+	/* Query CPUID_Fn80000020_EBX_x05 for number of ABMC counters */
+	cpuid_count(0x80000020, 5, &eax, &ebx, &ecx, &edx);
+	hw_res->mbm_assignable_counters = (ebx & 0xFFFF) + 1;
+}
+
 static void
 mba_wrmsr_amd(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r)
 {
@@ -815,6 +826,12 @@ static __init bool get_rdt_alloc_resources(void)
 	if (get_slow_mem_config())
 		ret = true;
 
+	if (rdt_cpu_has(X86_FEATURE_ABMC)) {
+		r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+		rdt_get_abmc_cfg(r);
+		ret = true;
+	}
+
 	return ret;
 }
 
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index a4f1aa15f0a2..01eb0522b42b 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -391,6 +391,8 @@ struct rdt_parse_data {
  *			resctrl_arch_get_num_closid() to avoid confusion
  *			with struct resctrl_schema's property of the same name,
  *			which has been corrected for features like CDP.
+ * @mbm_assignable_counters:
+ *			Maximum number of assignable ABMC counters
  * @msr_base:		Base MSR address for CBMs
  * @msr_update:		Function pointer to update QOS MSRs
  * @mon_scale:		cqm counter * mon_scale = occupancy in bytes
@@ -404,6 +406,7 @@ struct rdt_parse_data {
 struct rdt_hw_resource {
 	struct rdt_resource	r_resctrl;
 	u32			num_closid;
+	u32			mbm_assignable_counters;
 	unsigned int		msr_base;
 	void (*msr_update)	(struct rdt_domain *d, struct msr_param *m,
 				 struct rdt_resource *r);
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 69a1de92384a..9b82ba977d98 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1077,6 +1077,9 @@ static int rdt_mon_features_show(struct kernfs_open_file *of,
 			seq_printf(seq, "%s_config\n", mevt->name);
 	}
 
+	if (r->mbm_assign_capable)
+		seq_printf(seq, "mbm_assign_capable\n");
+
 	return 0;
 }
 
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 66942d7fba7f..1751a7b0a369 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -162,6 +162,7 @@ struct resctrl_schema;
  * @evt_list:		List of monitoring events
  * @fflags:		flags to choose base and info files
  * @cdp_capable:	Is the CDP feature available on this resource
+ * @assign_capable:	Does system capable of supporting monitor assignment?
  */
 struct rdt_resource {
 	int			rid;
@@ -182,6 +183,7 @@ struct rdt_resource {
 	struct list_head	evt_list;
 	unsigned long		fflags;
 	bool			cdp_capable;
+	bool			mbm_assign_capable;
 };
 
 /**
-- 
2.34.1