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[Xen-devel] [PATCH v13 00/10] enable Cache QoS Monitoring (CQM) feature

Changes from v12:
 - Address comments from Jan, like QoS feature setting when booting,
   avoid unbound memory allocation in Xen, put resource access
   hypercall in platform_hypercall.c to avoid creating new files, 
   specifically enumerate L3 cache size for CQM (instead of
   x86_cache_size), get random socket CPU in user space tools, and 
   also some coding styles. However the continue_hypercall_on_cpu()
   suggestion is not adopted in this version due to the potential
   issue in our usage case.
 - Add a white list to limit the capability for resource access from
   tool side.
 - Address comments from Ian on the xl/libxl/libxc side.

Changes from v11:
 - Turn off pqos and pqos_monitor in Xen command line by default.
 - Modify the original specific MSR access hypercall into a generic
   resource access hypercall. This hypercall could be used to access
   MSR, Port I/O, etc. Use platform_op to replace sysctl so that both
   dom0 kernel and userspace could use this hypercall.
 - Address various comments from Jan, Ian, Konrad, and Daniel.

Changes from v10:
 - Re-design and re-implement the whole logic. In this version,
   hypervisor provides basic mechanisms (like access MSRs) while all
   policies are put in user space.
   patch 1-3 provide a generic MSR hypercall for toolstack to access
   patch 4-9 implement the cache QoS monitoring feature

Changes from v9:
 - Revise the readonly mapping mechanism to share data between Xen and
   userspace. We create L3C buffer for each socket, share both buffer
   address MFNs and buffer MFNs to userspace.
 - Split the pqos.c into pqos.c and cqm.c for better code structure.
 - Show the total L3 cache size when issueing xl pqos-list cqm command.
 - Abstract a libxl_getcqminfo() function to fetch cqm data from Xen.
 - Several coding style fixes.

Changes from v8:
 - Address comments from Ian Campbell, including:
   * Modify the return handling for xc_sysctl();
   * Add man page items for platform QoS related commands.
   * Fix typo in commit message.

Changes from v7:
 - Address comments from Andrew Cooper, including:
   * Check CQM capability before allocating cpumask memory.
   * Move one function declaration into the correct patch.

Changes from v6:
 - Address comments from Jan Beulich, including:
   * Remove the unnecessary CPUID feature check.
   * Remove the unnecessary socket_cpu_map.
   * Spin_lock related changes, avoid spin_lock_irqsave().
   * Use readonly mapping to pass cqm data between Xen/Userspace,
     to avoid data copying.
   * Optimize RDMSR/WRMSR logic to avoid unnecessary calls.
   * Misc fixes including __read_mostly prefix, return value, etc.

Changes from v5:
 - Address comments from Dario Faggioli, including:
   * Define a new libxl_cqminfo structure to avoid reference of xc
     structure in libxl functions.
   * Use LOGE() instead of the LIBXL__LOG() functions.

Changes from v4:
 - When comparing xl cqm parameter, use strcmp instead of strncmp,
   otherwise, "xl pqos-attach cqmabcd domid" will be considered as
   a valid command line.
 - Address comments from Andrew Cooper, including:
   * Adjust the pqos parameter parsing function.
   * Modify the pqos related documentation.
   * Add a check for opt_cqm_max_rmid in initialization code.
   * Do not IPI CPU that is in same socket with current CPU.
 - Address comments from Dario Faggioli, including:
   * Fix an typo in export symbols.
   * Return correct libxl error code for qos related functions.
   * Abstract the error printing logic into a function.
 - Address comment from Daniel De Graaf, including:
   * Add return value in for pqos related check.
 - Address comments from Konrad Rzeszutek Wilk, including:
   * Modify the GPLv2 related file header, remove the address.

Changes from v3:
 - Use structure to better organize CQM related global variables.
 - Address comments from Andrew Cooper, including:
   * Remove the domain creation flag for CQM RMID allocation.
   * Adjust the boot parameter format, use custom_param().
   * Add documentation for the new added boot parameter.
   * Change QoS type flag to be uint64_t.
   * Initialize the per socket cpu bitmap in system boot time.
   * Remove get_cqm_avail() function.
   * Misc of format changes.
 - Address comment from Daniel De Graaf, including:
   * Use avc_current_has_perm() for XEN2__PQOS_OP that belongs to SECCLASS_XEN2.

Changes from v2:
 - Address comments from Andrew Cooper, including:
   * Merging tools stack changes into one patch.
   * Reduce the IPI number to one per socket.
   * Change structures for CQM data exchange between tools and Xen.
   * Misc of format/variable/function name changes.
 - Address comments from Konrad Rzeszutek Wilk, including:
   * Simplify the error printing logic.
   * Add xsm check for the new added hypercalls.

Changes from v1:
 - Address comments from Andrew Cooper, including:
   * Change function names, e.g., alloc_cqm_rmid(), system_supports_cqm(), etc.
   * Change some structure element order to save packing cost.
   * Correct some function's return value.
   * Some programming styles change.
   * ...

Future generations of Intel Xeon processor may offer monitoring capability in
each logical processor to measure specific quality-of-service metric,
for example, the Cache QoS Monitoring to get L3 cache occupancy.
Detailed information please refer to Intel SDM chapter 17.14.

Cache QoS Monitoring provides a layer of abstraction between applications and
logical processors through the use of Resource Monitoring IDs (RMIDs).
In Xen design, each guest in the system can be assigned an RMID independently,
while RMID=0 is reserved for monitoring domains that doesn't enable CQM service.
When any of the domain's vcpu is scheduled on a logical processor, the domain's
RMID will be activated by programming the value into one specific MSR, and when
the vcpu is scheduled out, a RMID=0 will be programmed into that MSR.
The Cache QoS Hardware tracks cache utilization of memory accesses according to
the RMIDs and reports monitored data via a counter register. With this solution,
we can get the knowledge how much L3 cache is used by a certain guest.

To attach QoS monitoring service to a certain guest:
xl pqos-monitor-attach domid

To detached CQM service from a guest:
xl pqos-monitor-detach domid

To get the L3 cache usage:
$ xl pqos-monitor-show cache_occupancy <domid>

The below data is just an example showing how the CQM related data is exposed to
end user.

[root@localhost]# xl pqos-monitor-show cache_occupancy
Total RMID: 55
Per-Socket L3 Cache Size: 35840 KB
Name                                        ID        Socket 0        Socket 1
Domain-0                                     0        20720 KB        15960 KB
ExampleHVMDomain                             1         4200 KB         2352 KB

Dongxiao Xu (10):
  x86: add generic resource (e.g. MSR) access hypercall
  xsm: add resource operation related xsm policy
  tools: provide interface for generic resource access
  x86: detect and initialize Platform QoS Monitoring feature
  x86: dynamically attach/detach QoS monitoring service for a guest
  x86: collect global QoS monitoring information
  x86: enable QoS monitoring for each domain RMID
  x86: add QoS monitoring related MSRs in allowed list
  xsm: add platform QoS related xsm policies
  tools: CMDs and APIs for Platform QoS Monitoring

 docs/man/xl.pod.1                            |  24 ++++
 docs/misc/xen-command-line.markdown          |  14 ++
 tools/flask/policy/policy/modules/xen/xen.if |   2 +-
 tools/flask/policy/policy/modules/xen/xen.te |   6 +-
 tools/libxc/Makefile                         |   2 +
 tools/libxc/xc_msr_x86.h                     |  36 +++++
 tools/libxc/xc_pqos.c                        | 204 +++++++++++++++++++++++++++
 tools/libxc/xc_private.h                     |  31 ++++
 tools/libxc/xc_resource.c                    |  53 +++++++
 tools/libxc/xenctrl.h                        |  22 +++
 tools/libxl/Makefile                         |   2 +-
 tools/libxl/libxl.h                          |  19 +++
 tools/libxl/libxl_pqos.c                     | 184 ++++++++++++++++++++++++
 tools/libxl/libxl_types.idl                  |   4 +
 tools/libxl/libxl_utils.c                    |  28 ++++
 tools/libxl/xl.h                             |   3 +
 tools/libxl/xl_cmdimpl.c                     | 131 +++++++++++++++++
 tools/libxl/xl_cmdtable.c                    |  17 +++
 xen/arch/x86/Makefile                        |   2 +
 xen/arch/x86/cpu/intel_cacheinfo.c           |  50 +------
 xen/arch/x86/domain.c                        |   8 ++
 xen/arch/x86/domctl.c                        |  29 ++++
 xen/arch/x86/platform_hypercall.c            |  86 +++++++++++
 xen/arch/x86/pqos.c                          | 194 +++++++++++++++++++++++++
 xen/arch/x86/setup.c                         |   3 +
 xen/arch/x86/sysctl.c                        |  43 ++++++
 xen/include/asm-x86/cpufeature.h             |   1 +
 xen/include/asm-x86/domain.h                 |   2 +
 xen/include/asm-x86/msr-index.h              |   5 +
 xen/include/asm-x86/pqos.h                   |  65 +++++++++
 xen/include/public/domctl.h                  |  12 ++
 xen/include/public/platform.h                |  24 ++++
 xen/include/public/sysctl.h                  |  14 ++
 xen/include/xlat.lst                         |   1 +
 xen/xsm/flask/hooks.c                        |  11 ++
 xen/xsm/flask/policy/access_vectors          |  18 ++-
 xen/xsm/flask/policy/security_classes        |   1 +
 37 files changed, 1298 insertions(+), 53 deletions(-)
 create mode 100644 tools/libxc/xc_msr_x86.h
 create mode 100644 tools/libxc/xc_pqos.c
 create mode 100644 tools/libxc/xc_resource.c
 create mode 100644 tools/libxl/libxl_pqos.c
 create mode 100644 xen/arch/x86/pqos.c
 create mode 100644 xen/include/asm-x86/pqos.h


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