x86/resctrl: Implement resctrl_arch_reset_cntr() and resctrl_arch_cntr_read()

System software reads resctrl event data for a particular resource by writing
the RMID and Event Identifier (EvtID) to the QM_EVTSEL register and then
reading the event data from the QM_CTR register.

In ABMC mode, the event data of a specific counter ID is read by setting the
following fields: QM_EVTSEL.ExtendedEvtID = 1, QM_EVTSEL.EvtID = L3CacheABMC
(=1) and setting QM_EVTSEL.RMID to the desired counter ID.  Reading the QM_CTR
then returns the contents of the specified counter ID.  RMID_VAL_ERROR bit is
set if the counter configuration is invalid, or if an invalid counter ID is
set in the QM_EVTSEL.RMID field.  RMID_VAL_UNAVAIL bit is set if the counter
data is unavailable.

Introduce resctrl_arch_reset_cntr() and resctrl_arch_cntr_read() to reset and
read event data for a specific counter.

Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com

arch/x86/kernel/cpu/resctrl/internal.h

@@ -40,6 +40,12 @@ struct arch_mbm_state {
 /* Setting bit 0 in L3_QOS_EXT_CFG enables the ABMC feature. */
 #define ABMC_ENABLE_BIT			0
 
+/*
+ * Qos Event Identifiers.
+ */
+#define ABMC_EXTENDED_EVT_ID		BIT(31)
+#define ABMC_EVT_ID			BIT(0)
+
 /**
  * struct rdt_hw_ctrl_domain - Arch private attributes of a set of CPUs that share
  *			       a resource for a control function

arch/x86/kernel/cpu/resctrl/monitor.c

@@ -259,6 +259,75 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_mon_domain *d,
 	return 0;
 }
 
+static int __cntr_id_read(u32 cntr_id, u64 *val)
+{
+	u64 msr_val;
+
+	/*
+	 * QM_EVTSEL Register definition:
+	 * =======================================================
+	 * Bits    Mnemonic        Description
+	 * =======================================================
+	 * 63:44   --              Reserved
+	 * 43:32   RMID            RMID or counter ID in ABMC mode
+	 *                         when reading an MBM event
+	 * 31      ExtendedEvtID   Extended Event Identifier
+	 * 30:8    --              Reserved
+	 * 7:0     EvtID           Event Identifier
+	 * =======================================================
+	 * The contents of a specific counter can be read by setting the
+	 * following fields in QM_EVTSEL.ExtendedEvtID(=1) and
+	 * QM_EVTSEL.EvtID = L3CacheABMC (=1) and setting QM_EVTSEL.RMID
+	 * to the desired counter ID. Reading the QM_CTR then returns the
+	 * contents of the specified counter. The RMID_VAL_ERROR bit is set
+	 * if the counter configuration is invalid, or if an invalid counter
+	 * ID is set in the QM_EVTSEL.RMID field.  The RMID_VAL_UNAVAIL bit
+	 * is set if the counter data is unavailable.
+	 */
+	wrmsr(MSR_IA32_QM_EVTSEL, ABMC_EXTENDED_EVT_ID | ABMC_EVT_ID, cntr_id);
+	rdmsrl(MSR_IA32_QM_CTR, msr_val);
+
+	if (msr_val & RMID_VAL_ERROR)
+		return -EIO;
+	if (msr_val & RMID_VAL_UNAVAIL)
+		return -EINVAL;
+
+	*val = msr_val;
+	return 0;
+}
+
+void resctrl_arch_reset_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
+			     u32 unused, u32 rmid, int cntr_id,
+			     enum resctrl_event_id eventid)
+{
+	struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
+	struct arch_mbm_state *am;
+
+	am = get_arch_mbm_state(hw_dom, rmid, eventid);
+	if (am) {
+		memset(am, 0, sizeof(*am));
+
+		/* Record any initial, non-zero count value. */
+		__cntr_id_read(cntr_id, &am->prev_msr);
+	}
+}
+
+int resctrl_arch_cntr_read(struct rdt_resource *r, struct rdt_mon_domain *d,
+			   u32 unused, u32 rmid, int cntr_id,
+			   enum resctrl_event_id eventid, u64 *val)
+{
+	u64 msr_val;
+	int ret;
+
+	ret = __cntr_id_read(cntr_id, &msr_val);
+	if (ret)
+		return ret;
+
+	*val = get_corrected_val(r, d, rmid, eventid, msr_val);
+
+	return 0;
+}
+
 /*
  * The power-on reset value of MSR_RMID_SNC_CONFIG is 0x1
  * which indicates that RMIDs are configured in legacy mode.