linux.git/arch/x86/kernel/cpu/resctrl/monitor.c, branch v6.0

x86/resctrl: Remove redundant assignment to variable chunks

2021-12-09T17:57:16+00:00

The variable chunks is being shifted right and re-assinged the shifted
value which is then returned. Since chunks is not being read afterwards
the assignment is redundant and the >>= operator can be replaced with a
shift >> operator instead.

Signed-off-by: Colin Ian King 
Signed-off-by: Dave Hansen 
Reviewed-by: Fenghua Yu 
Link: https://lkml.kernel.org/r/20211207223735.35173-1-colin.i.king@gmail.com

Merge tag 'x86_cache_for_v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-08-30T20:31:36+00:00

Pull x86 resource control updates from Borislav Petkov:
 "A first round of changes towards splitting the arch-specific bits from
  the filesystem bits of resctrl, the ultimate goal being to support
  ARM's equivalent technology MPAM, with the same fs interface (James
  Morse)"

* tag 'x86_cache_for_v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
  x86/resctrl: Make resctrl_arch_get_config() return its value
  x86/resctrl: Merge the CDP resources
  x86/resctrl: Expand resctrl_arch_update_domains()'s msr_param range
  x86/resctrl: Remove rdt_cdp_peer_get()
  x86/resctrl: Merge the ctrl_val arrays
  x86/resctrl: Calculate the index from the configuration type
  x86/resctrl: Apply offset correction when config is staged
  x86/resctrl: Make ctrlval arrays the same size
  x86/resctrl: Pass configuration type to resctrl_arch_get_config()
  x86/resctrl: Add a helper to read a closid's configuration
  x86/resctrl: Rename update_domains() to resctrl_arch_update_domains()
  x86/resctrl: Allow different CODE/DATA configurations to be staged
  x86/resctrl: Group staged configuration into a separate struct
  x86/resctrl: Move the schemata names into struct resctrl_schema
  x86/resctrl: Add a helper to read/set the CDP configuration
  x86/resctrl: Swizzle rdt_resource and resctrl_schema in pseudo_lock_region
  x86/resctrl: Pass the schema to resctrl filesystem functions
  x86/resctrl: Add resctrl_arch_get_num_closid()
  x86/resctrl: Store the effective num_closid in the schema
  x86/resctrl: Walk the resctrl schema list instead of an arch list
  ...

x86/resctrl: Fix a maybe-uninitialized build warning treated as error

2021-08-22T07:11:29+00:00

The recent commit

  064855a69003 ("x86/resctrl: Fix default monitoring groups reporting")

caused a RHEL build failure with an uninitialized variable warning
treated as an error because it removed the default case snippet.

The RHEL Makefile uses '-Werror=maybe-uninitialized' to force possibly
uninitialized variable warnings to be treated as errors. This is also
reported by smatch via the 0day robot.

The error from the RHEL build is:

  arch/x86/kernel/cpu/resctrl/monitor.c: In function ‘__mon_event_count’:
  arch/x86/kernel/cpu/resctrl/monitor.c:261:12: error: ‘m’ may be used
  uninitialized in this function [-Werror=maybe-uninitialized]
    m->chunks += chunks;
              ^~

The upstream Makefile does not build using '-Werror=maybe-uninitialized'.
So, the problem is not seen there. Fix the problem by putting back the
default case snippet.

 [ bp: note that there's nothing wrong with the code and other compilers
   do not trigger this warning - this is being done just so the RHEL compiler
   is happy. ]

Fixes: 064855a69003 ("x86/resctrl: Fix default monitoring groups reporting")
Reported-by: Terry Bowman 
Reported-by: kernel test robot 
Signed-off-by: Babu Moger 
Signed-off-by: Borislav Petkov 
Reviewed-by: Reinette Chatre 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/162949631908.23903.17090272726012848523.stgit@bmoger-ubuntu

x86/resctrl: Fix default monitoring groups reporting

2021-08-12T18:12:20+00:00

Creating a new sub monitoring group in the root /sys/fs/resctrl leads to
getting the "Unavailable" value for mbm_total_bytes and mbm_local_bytes
on the entire filesystem.

Steps to reproduce:

  1. mount -t resctrl resctrl /sys/fs/resctrl/

  2. cd /sys/fs/resctrl/

  3. cat mon_data/mon_L3_00/mbm_total_bytes
     23189832

  4. Create sub monitor group:
  mkdir mon_groups/test1

  5. cat mon_data/mon_L3_00/mbm_total_bytes
     Unavailable

When a new monitoring group is created, a new RMID is assigned to the
new group. But the RMID is not active yet. When the events are read on
the new RMID, it is expected to report the status as "Unavailable".

When the user reads the events on the default monitoring group with
multiple subgroups, the events on all subgroups are consolidated
together. Currently, if any of the RMID reads report as "Unavailable",
then everything will be reported as "Unavailable".

Fix the issue by discarding the "Unavailable" reads and reporting all
the successful RMID reads. This is not a problem on Intel systems as
Intel reports 0 on Inactive RMIDs.

Fixes: d89b7379015f ("x86/intel_rdt/cqm: Add mon_data")
Reported-by: Paweł Szulik 
Signed-off-by: Babu Moger 
Signed-off-by: Borislav Petkov 
Acked-by: Reinette Chatre 
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213311
Link: https://lkml.kernel.org/r/162793309296.9224.15871659871696482080.stgit@bmoger-ubuntu

x86/resctrl: Make resctrl_arch_get_config() return its value

2021-08-11T16:42:53+00:00

resctrl_arch_get_config() has no return, but does pass a single value
back via one of its arguments.

Return the value instead.

Suggested-by: Borislav Petkov 
Signed-off-by: James Morse 
Signed-off-by: Borislav Petkov 
Link: https://lkml.kernel.org/r/20210811163831.14917-1-james.morse@arm.com

x86/resctrl: Pass configuration type to resctrl_arch_get_config()

2021-08-11T15:53:53+00:00

The ctrl_val[] array for a struct rdt_hw_resource only holds
configurations of one type. The type is implicit.

Once the CDP resources are merged, the ctrl_val[] array will hold all
the configurations for the hardware resource. When a particular type of
configuration is needed, it must be specified explicitly.

Pass the expected type from the schema into resctrl_arch_get_config().
Nothing uses this yet, but once a single ctrl_val[] array is used for
the three struct rdt_hw_resources that share hardware, the type will be
used to return the correct configuration value from the shared array.

Signed-off-by: James Morse 
Signed-off-by: Borislav Petkov 
Reviewed-by: Jamie Iles 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lkml.kernel.org/r/20210728170637.25610-18-james.morse@arm.com

x86/resctrl: Add a helper to read a closid's configuration

2021-08-11T15:46:34+00:00

Functions like show_doms() reach into the architecture's private
structure to retrieve the configuration from the struct rdt_hw_resource.

The hardware configuration may look completely different to the
values resctrl gets from user-space. The staged configuration and
resctrl_arch_update_domains() allow the architecture to convert or
translate these values.

Resctrl shouldn't read or write the ctrl_val[] values directly. Add
a helper to read the current configuration. This will allow another
architecture to scale the bitmaps if necessary, and possibly use
controls that don't take the user-space control format at all.

Of the remaining functions that access ctrl_val[] directly,
apply_config() is part of the architecture-specific code, and is
called via resctrl_arch_update_domains(). reset_all_ctrls() will be an
architecture specific helper.

update_mba_bw() manipulates both ctrl_val[], mbps_val[] and the
hardware. The mbps_val[] that matches the mba_sc state of the resource
is changed, but the other is left unchanged. Abstracting this is the
subject of later patches that affect set_mba_sc() too.

Signed-off-by: James Morse 
Signed-off-by: Borislav Petkov 
Reviewed-by: Jamie Iles 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lkml.kernel.org/r/20210728170637.25610-17-james.morse@arm.com

x86/resctrl: Split struct rdt_domain

2021-08-11T10:00:43+00:00

resctrl is the defacto Linux ABI for SoC resource partitioning features.

To support it on another architecture, it needs to be abstracted from
the features provided by Intel RDT and AMD PQoS, and moved to /fs/.
struct rdt_domain contains a mix of architecture private details and
properties of the filesystem interface user-space uses.

Continue by splitting struct rdt_domain, into an architecture private
'hw' struct, which contains the common resctrl structure that would be
used by any architecture. The hardware values in ctrl_val and mbps_val
need to be accessed via helpers to allow another architecture to convert
these into a different format if necessary. After this split, filesystem
code paths touching a 'hw' struct indicates where an abstraction is
needed.

Splitting this structure only moves types around, and should not lead
to any change in behaviour.

Signed-off-by: James Morse 
Signed-off-by: Borislav Petkov 
Reviewed-by: Jamie Iles 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lkml.kernel.org/r/20210728170637.25610-3-james.morse@arm.com

x86/resctrl: Split struct rdt_resource

2021-08-11T09:51:34+00:00

resctrl is the defacto Linux ABI for SoC resource partitioning features.

To support it on another architecture, it needs to be abstracted from
the features provided by Intel RDT and AMD PQoS, and moved to /fs/.
struct rdt_resource contains a mix of architecture private details
and properties of the filesystem interface user-space uses.

Start by splitting struct rdt_resource, into an architecture private
'hw' struct, which contains the common resctrl structure that would be
used by any architecture. The foreach helpers are most commonly used by
the filesystem code, and should return the common resctrl structure.
for_each_rdt_resource() is changed to walk the common structure in its
parent arch private structure.

Move as much of the structure as possible into the common structure
in the core code's header file. The x86 hardware accessors remain
part of the architecture private code, as do num_closid, mon_scale
and mbm_width.

mon_scale and mbm_width are used to detect overflow of the hardware
counters, and convert them from their native size to bytes. Any
cross-architecture abstraction should be in terms of bytes, making
these properties private.

The hardware's num_closid is kept in the private structure to force the
filesystem code to use a helper to access it. MPAM would return a single
value for the system, regardless of the resource. Using the helper
prevents this field from being confused with the version of num_closid
that is being exposed to user-space (added in a later patch).

After this split, filesystem code touching a 'hw' struct indicates
where an abstraction is needed.

Splitting this structure only moves types around, and should not lead
to any change in behaviour.

Signed-off-by: James Morse 
Signed-off-by: Borislav Petkov 
Reviewed-by: Jamie Iles 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lkml.kernel.org/r/20210728170637.25610-2-james.morse@arm.com

x86/resctrl: Fix init const confusion

2021-05-05T19:50:14+00:00

const variable must be initconst, not initdata.

Signed-off-by: Andi Kleen 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20210425211229.3157674-1-ak@linux.intel.com