Hi Babu,
On 5/24/24 5:23 AM, Babu Moger wrote:
The ABMC feature provides an option to the user to assign a hardware
counter to an RMID and monitor the bandwidth as long as the counter
is assigned. The bandwidth events will be tracked by the hardware until
the user changes the configuration. Each resctrl group can configure
maximum two counters, one for total event and one for local event.
The counters are configured by writing to MSR L3_QOS_ABMC_CFG.
Configuration is done by setting the counter id, bandwidth source (RMID),
bandwidth types. Reading L3_QOS_ABMC_DSC returns the configuration of
What is a "bandwidth type" here?
the counter id specified in L3_QOS_ABMC_CFG.
Attempts to read or write these MSRs when ABMC is not enabled will result
in a #GP(0) exception.
MSR L3_QOS_ABMC_CFG (0xC000_03FDh) and L3_QOS_ABMC_DSC (0xC000_03FEh)
details.
==========================================================================
Bits Mnemonic Description Access Type Reset Value
==========================================================================
63 CfgEn Configuration Enable R/W 0
62 CtrEn Counter Enable R/W 0
61:53 – Reserved MBZ 0
52:48 CtrID Counter Identifier R/W 0
47 IsCOS BwSrc field is a COS R/W 0
(not an RMID)
46:44 – Reserved MBZ 0
43:32 BwSrc Bandwidth Source R/W 0
(RMID or COS)
31:0 BwType Bandwidth types to R/W 0
track for this counter
==========================================================================
This is copy&paste from AMD spec but needs some translation to map it to
resctrl.
The feature details are documented in the 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
---
v4: Added more descriptions.
Changed the name abmc_ctr_id to ctr_id.
Added L3_QOS_ABMC_DSC. Used for reading the configuration.
v3: No changes.
v2: No changes.
---
arch/x86/include/asm/msr-index.h | 2 ++
arch/x86/kernel/cpu/resctrl/internal.h | 30 ++++++++++++++++++++++++++
2 files changed, 32 insertions(+)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 5f9a0139e98c..6d2fe39ac68f 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -1172,6 +1172,8 @@
#define MSR_IA32_SMBA_BW_BASE 0xc0000280
#define MSR_IA32_EVT_CFG_BASE 0xc0000400
#define MSR_IA32_L3_QOS_EXT_CFG 0xc00003ff
+#define MSR_IA32_L3_QOS_ABMC_CFG 0xc00003fd
+#define MSR_IA32_L3_QOS_ABMC_DSC 0xc00003fe
/* MSR_IA32_VMX_MISC bits */
#define MSR_IA32_VMX_MISC_INTEL_PT (1ULL << 14)
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 60a1ca0a11a7..45ed33f4f0ff 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -107,6 +107,9 @@ cpumask_any_housekeeping(const struct cpumask *mask, int exclude_cpu)
#define ASSIGN_TOTAL BIT(QOS_L3_MBM_TOTAL_EVENT_ID)
#define ASSIGN_LOCAL BIT(QOS_L3_MBM_LOCAL_EVENT_ID)
+/* Maximum assignable counters per resctrl group */
+#define MAX_CNTRS 2
+
struct rdt_fs_context {
struct kernfs_fs_context kfc;
bool enable_cdpl2;
@@ -211,6 +214,7 @@ enum rdtgrp_mode {
* @crdtgrp_list: child rdtgroup node list
* @rmid: rmid for this rdtgroup
* @mon_state: Assignment state of the group
+ * @ctr_id: ABMC counter ids assigned to this group
*/
struct mongroup {
struct kernfs_node *mon_data_kn;
@@ -218,6 +222,7 @@ struct mongroup {
struct list_head crdtgrp_list;
u32 rmid;
u32 mon_state;
+ u32 ctr_id[MAX_CNTRS];
To match "num_cntrs" it seems "cntr_id" may be more appropriate?
};
/**
@@ -568,6 +573,31 @@ union cpuid_0x10_x_edx {
unsigned int full;
};
+/*
+ * ABMC counters can be configured by writing to L3_QOS_ABMC_CFG.
extra space
+ * @bw_type : Bandwidth types to track for this counter
What is a "Bandwidth type"? What are possible values?
+ * @bw_src : Bandwidth Source (RMID or CLOSID)
+ * @reserved1 : Reserved
+ * @is_cos : BwSrc field is a COS (not an RMID)
Please be consistent wrt "CLOS"/"CLOSID" in comment and member name
+ * @ctr_id : Counter Identifier
Please be consistent with "cntr" vs "ctr". Earlier the series
introduces "num_cntrs" so cntr seems appropriate?
+ * @reserved : Reserved
+ * @ctr_en : Counter Enable bit
+ * @cfg_en : Configuration Enable bit
Why are there two enable bits? How are they used?
(please match other kernel doc wrt : usage)
+ */
+union l3_qos_abmc_cfg {
+ struct {
+ unsigned long bw_type :32,
+ bw_src :12,
+ reserved1: 3,
+ is_cos : 1,
+ ctr_id : 5,
+ reserved : 9,
+ ctr_en : 1,
+ cfg_en : 1;
+ } split;
+ unsigned long full;
+};
+
void rdt_last_cmd_clear(void);
void rdt_last_cmd_puts(const char *s);
__printf(1, 2)
Reinette
