AR review updates

qos.bib

@@ -11,6 +11,10 @@ @electronic{SSQOSID
   title = {RISC-V Quality-of-Service (QoS) Identifiers},
   url = {https://github.com/riscv/riscv-ssqosid}
 }
+@electronic{STATEEN,
+  title = {RISC-V State Enable Extension},
+  url = {https://drive.google.com/file/d/1dhI6OzVbejQbfwyBTuwK9U4VUmW8ii4o/view}
+}
 @INPROCEEDINGS{SSAMPLE,
   author={Thornock, N.C. and Flanagan, J.K.},
   booktitle={2000 Winter Simulation Conference Proceedings (Cat. No.00CH37165)},

qos_bandwidth.adoc

@@ -49,10 +49,12 @@ bandwidth-controller capabilities.
 {reg: [
   {bits:  8, name: 'VER'},
   {bits: 16, name: 'NBWBLKS'},
-  {bits:  8, name: 'WPRI'},
+  {bits:  1, name: 'RPFX'},
+  {bits:  4, name: 'P'},
+  {bits:  3, name: 'WPRI'},
   {bits: 16, name: 'MRBWB'},
   {bits: 16, name: 'WPRI'},
-], config:{lanes: 2, hspace:1024}}
+], config:{lanes: 4, hspace:1024}}
 ....
 
 The `VER` field holds the version of the specification implemented by the
@@ -83,6 +85,12 @@ allowing all available bandwidth blocks to be reserved for allocation, the
 bandwidth controller can handle such transient inaccuracies.
 ====
 
+If `RPFX` is 1, the controller uses `RCID` in the requests along with `P` least
+significant bits of the `MCID` carried in the request to compute an effective
+`MCID` (<<EMCID>>) to identify the monitoring counter. Legal values of `P` range
+from 0 to 12. If `RPFX` is 0, `P` is set to 0, and the effective `MCID` is the
+same as the `MCID` in the request.
+
 [[BC_MCTL]]
 === Bandwidth usage monitoring control (`bc_mon_ctl`)
 

qos_capacity.adoc

@@ -24,10 +24,30 @@ allocation by ways might define a _capacity block_ to be the cache blocks in one
 way of the cache.
 ====
 
+The capacity allocation affects the decision regarding which _capacity blocks_
+to use when a new _capacity unit_ is requested by a workload but usually does
+not affect other operations of the controller.
+
+[NOTE]
+====
+For example, when a request is made to a cache controller, the request involves
+scanning the entire cache to determine if the requested data is present. If the
+data is located, then the request is fulfilled using this data, even if the
+cache block containing the data was initially allocated for a different
+workload. The data continues to reside in the same cache block. Consequently,
+the cache lookup function remains unaffected by the capacity allocation
+constraints set for the workload initiating the request. Conversely, if the data
+is not found, a new cache block must be allocated. This allocation is executed
+using the _capacity blocks_ assigned to the workload that made the request.
+Hence, a workload may only trigger evictions within _capacity blocks_ designated
+to it but can access shared data in _capacity blocks_ allocated to other
+workloads.
+====
+
 [[CC_REG]]
 .Capacity-controller QoS register layout
 [width=100%]
-[%header, cols="^3,10,^3, 18, 5"]
+[%header, cols="^3,10,^4, 18, 5"]
 |===
 |Offset|Name              |Size    |Description                 | Optional?
 |0     |`cc_capabilities` |8       |<<CC_CAP, Capabilities >>   | No
@@ -37,7 +57,7 @@ way of the cache.
                                     counter value>>             | Yes
 |24    |`cc_alloc_ctl`    |8       |<<CC_ALLOC, Capacity
                                     allocation control >>       | Yes
-|32    |`cc_block_mask`   |`M` * 8 |<<CC_BMASK, Capacity
+|32    |`cc_block_mask`   |`BMW`/8 |<<CC_BMASK, Capacity
                                     block mask >>               | Yes
 |N     |`cc_cunits`       |8       |<<CC_CUNITS, Capacity units
                                     count>>                     | Yes
@@ -46,7 +66,9 @@ way of the cache.
 The size and offset in <<CC_REG>> are specified in bytes.
 
 The size of the `cc_block_mask` register is determined by the `NCBLKS` field
-of the `cc_capabilities` register but is always a multiple of 8 bytes.
+of the `cc_capabilities` register but is always a multiple of 8 bytes. The
+formula for determination of `BMW` is defined in <<CC_BMASK>>. The offset `N` is
+determined as `32 + BMW/8`.
 
 The reset value is 0 for the following register fields.
 
@@ -77,7 +99,9 @@ capacity-controller capabilities.
   {bits: 16, name: 'NCBLKS'},
   {bits:  1, name: 'FRCID'},
   {bits:  1, name: 'CUNITS'},
-  {bits: 38, name: 'WPRI'},
+  {bits:  1, name: 'RPFX'},
+  {bits:  4, name: 'P'},
+  {bits: 33, name: 'WPRI'},
 ], config:{lanes: 4, hspace:1024}}
 ....
 
@@ -105,6 +129,12 @@ units_ that can be occupied by an `RCID` in _capacity blocks_ allocated to it.
 If `FRCID` is 1, the controller supports an operation to flush and deallocate
 the _capacity blocks_ occupied by an `RCID`.
 
+If `RPFX` is 1, the controller uses `RCID` in the requests along with `P` least
+significant bits of the `MCID` carried in the request to compute an effective
+`MCID` (<<EMCID>>) to identify the monitoring counter. Legal values of `P` range
+from 0 to 12. If `RPFX` is 0, `P` is set to 0, and the effective `MCID` is the
+same as the `MCID` in the request.
+
 [[CC_MCTL]]
 === Capacity usage monitoring control (`cc_mon_ctl`)
 

qos_header.adoc

@@ -37,7 +37,7 @@ endif::[]
 :xrefstyle: short
 
 = RISC-V Capacity and Bandwidth QoS Register Interface
-RISC-V CMQRI Task Group
+RISC-V CBQRI Task Group
 
 // Preamble
 [WARNING]

qos_hw_guidelines.adoc

@@ -21,15 +21,15 @@ large pool of `MCID` speeds up this analysis.
 
 [NOTE]
 ====
-To achieve maximum flexibility in the allocation of QoS IDs to workloads, it is
+To maximize flexibility in the allocation of QoS IDs to workloads, it is
 recommended that all resource controllers in the system support an identical
-number of `RCID` and `MCID`. Requests typically need to be processed by multiple
-controllers, such as caches, fabrics, and memory controllers. In such cases, if
-not all controllers accessed by a request support an identical number of IDs,
-software will be constrained, using only the IDs supported by all controllers.
+number of `RCID` and `MCID`, as well as a uniform mode of operation — either
+direct or RCID-prefixed — for determining the effective `MCID`. Uniformity
+ensures that software is not constrained by the lowest common denominator of ID
+support when requests are processed by multiple controllers, such as caches,
+fabrics, and memory controllers.
 ====
 
-
 === Sizing monitoring counters
 
 Typically software samples the monitoring counters periodically to monitor

qos_identifiers.adoc

@@ -20,19 +20,36 @@ controllers that control accesses to such shared resources.
 Guidelines for sizing the QoS IDs and need for differentiated IDs for monitoring
 is discussed in <<QOS_SIZING>>.
 
+[[EMCID]]
 === Associating `RCID` and `MCID` with requests
 
 The `RCID` in the request is used by the resource controllers to determine the
 resource allocations (e.g., cache occupancy limits, memory bandwidth limits,
-etc.) to enforce. The `MCID` in the request is used by the resource controllers
-to identify the ID of a counter to monitor resource usage (e.g., cache
-occupancy, memory bandwidth, etc.).
+etc.) to enforce.
+
+The `MCID` in the request is used by the resource controllers to identify the ID
+of a counter to monitor resource usage (e.g., cache occupancy, memory bandwidth,
+etc.). Two modes of operation are supported by CBQRI. In the direct mode, the
+`MCID` carried with the request is directly used by the controller to identify
+the counter and is the effective `MCID`. In the RCID-prefixed mode, the
+controller identifies the counter for monitoring using an effective `MCID`
+computed as:
+
+----
+    Effective MCID = (RCID << P) | (MCID & ((1 << P) - 1))
+----
+
+Legal values of `P` range from 0 to 12 and are enumerated in the capability
+register of the controller. Software should use the effective `MCID` as the
+`MCID` operand to the controller for operations on the monitoring counters.
 
 ==== RISC-V hart initiated requests (Ssqosid)
 
 The Ssqosid extension cite:[SSQOSID] introduces a read/write S/HS-mode register
 (`sqoscfg`) to configure QoS Identifiers to be used with requests made by the
-hart to shared resources.
+hart to shared resources. If extension Smstateen cite:[STATEEN] is implemented
+then bit (TBA) of `mstateen0` controls access to `sqoscfg` from privilege modes
+less than M.
 
 ==== Device initiated requests
 

qos_iommu.adoc

@@ -1,13 +1,17 @@
 [[QOS_IOMMU]]
 == IOMMU extension for QoS ID
 
-Monitoring or allocation of resources accessed by the IOMMU and devices governed
-by the IOMMU requires a way to associate QoS IDs with such requests. This
-section specifies a RISC-V IOMMU cite:[IOMMU] extension to:
+A method to associate QoS IDs with requests to access resources by the IOMMU, as
+well as with devices governed by it, is required for effective monitoring and
+allocation. This section specifies a RISC-V IOMMU cite:[IOMMU] extension to:
 
 * Configure and associate QoS IDs for device-originated requests.
 * Configure and associate QoS IDs for IOMMU-originated requests.
 
+The size (or width) of `RCID` and `MCID`, as fields in registers or in data
+structures, supported by the IOMMU must be at least as large as that supported
+by any RISC-V application processor hart in the system.
+
 === IOMMU registers
 
 The specified memory-mapped register layout defines a new IOMMU register named
@@ -35,7 +39,9 @@ If the reset value for `ddtp.iommu_mode` field is `Bare`, then the
 At reset, it is required that the `RCID` field of `iommu_qosid` be set to 0 if
 the IOMMU is in `Bare` mode, as typically the resource controllers in the
 SoC default to a reset behavior of associating all capacity or bandwidth to the
-`RCID` value of 0.
+`RCID` value of 0. When the reset value of the `ddtp.iommu_mode` is not `Bare`,
+the `iommu_qosid` register should be initialized by software prior to changing
+the mode to allow DMA.
 ====
 
 ==== IOMMU capabilities (`capabilities`)
@@ -107,9 +113,9 @@ The `iommu_qosid` register fields are defined as follows:
 [%header, cols="^1,2,^1,5"]
 |===
 |Bits  |Field      |Attribute | Description
-|11:0  |`RCID`     |WARL      | RCID for IOMMU initiated requests.
+|11:0  |`RCID`     |WARL      | `RCID` for IOMMU-initiated requests.
 |15:12 |reserved   |WPRI      | Reserved for standard use.
-|27:16 |`MCID`     |WARL      | MCID for IOMMU initiated requests.
+|27:16 |`MCID`     |WARL      | `MCID` for IOMMU-initiated requests.
 |31:28 |reserved   |WPRI      | Reserved for standard use.
 |===
 

readme.adoc

@@ -1,6 +1,6 @@
 = RISC-V Capacity and Bandwidth Controller QoS Register Interface
 
-This document is capturing discussions at the CMQRI TG and attempts to document the baseline.
+This document is capturing discussions at the CBQRI TG and attempts to document the baseline.
 This is not official specification and everything in this document may change. 
 
 Quality of Service (QoS) is the minimal end-to-end performance that is guaranteed in advance