Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Will Deacon:
 "We've got a little less than normal thanks to the holidays in
  December, but there's the usual summary below. The highlight is
  probably the 52-bit physical addressing (LPA2) clean-up from Ard.

  Confidential Computing:

   - Register a platform device when running in CCA realm mode to enable
     automatic loading of dependent modules

  CPU Features:

   - Update a bunch of system register definitions to pick up new field
     encodings from the architectural documentation

   - Add hwcaps and selftests for the new (2024) dpISA extensions

  Documentation:

   - Update EL3 (firmware) requirements for booting Linux on modern
     arm64 designs

   - Remove stale information about the kernel virtual memory map

  Miscellaneous:

   - Minor cleanups and typo fixes

  Memory management:

   - Fix vmemmap_check_pmd() to look at the PMD type bits

   - LPA2 (52-bit physical addressing) cleanups and minor fixes

   - Adjust physical address space depending upon whether or not LPA2 is
     enabled

  Perf and PMUs:

   - Add port filtering support for NVIDIA's NVLINK-C2C Coresight PMU

   - Extend AXI filtering support for the DDR PMU on NXP IMX SoCs

   - Fix Designware PCIe PMU event numbering

   - Add generic branch events for the Apple M1 CPU PMU

   - Add support for Marvell Odyssey DDR and LLC-TAD PMUs

   - Cleanups to the Hisilicon DDRC and Uncore PMU code

   - Advertise discard mode for the SPE PMU

   - Add the perf users mailing list to our MAINTAINERS entry"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (64 commits)
  Documentation: arm64: Remove stale and redundant virtual memory diagrams
  perf docs: arm_spe: Document new discard mode
  perf: arm_spe: Add format option for discard mode
  MAINTAINERS: Add perf list for drivers/perf/
  arm64: Remove duplicate included header
  drivers/perf: apple_m1: Map generic branch events
  arm64: rsi: Add automatic arm-cca-guest module loading
  kselftest/arm64: Add 2024 dpISA extensions to hwcap test
  KVM: arm64: Allow control of dpISA extensions in ID_AA64ISAR3_EL1
  arm64/hwcap: Describe 2024 dpISA extensions to userspace
  arm64/sysreg: Update ID_AA64SMFR0_EL1 to DDI0601 2024-12
  arm64: Filter out SVE hwcaps when FEAT_SVE isn't implemented
  drivers/perf: hisi: Set correct IRQ affinity for PMUs with no association
  arm64/sme: Move storage of reg_smidr to __cpuinfo_store_cpu()
  arm64: mm: Test for pmd_sect() in vmemmap_check_pmd()
  arm64/mm: Replace open encodings with PXD_TABLE_BIT
  arm64/mm: Rename pte_mkpresent() as pte_mkvalid()
  arm64/sysreg: Update ID_AA64ISAR2_EL1 to DDI0601 2024-09
  arm64/sysreg: Update ID_AA64ZFR0_EL1 to DDI0601 2024-09
  arm64/sysreg: Update ID_AA64FPFR0_EL1 to DDI0601 2024-09
  ...

1 files changed, 26 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf-arm-spe.txt b/tools/perf/Documentation/perf-arm-spe.txt
index de2b0b479249..37afade4f1b2 100644
--- a/tools/perf/Documentation/perf-arm-spe.txt
+++ b/tools/perf/Documentation/perf-arm-spe.txt
@@ -150,6 +150,7 @@ arm_spe/load_filter=1,min_latency=10/'
   pct_enable=1        - collect physical timestamp instead of virtual timestamp (PMSCR.PCT) - requires privilege
   store_filter=1      - collect stores only (PMSFCR.ST)
   ts_enable=1         - enable timestamping with value of generic timer (PMSCR.TS)
+  discard=1           - enable SPE PMU events but don't collect sample data - see 'Discard mode' (PMBLIMITR.FM = DISCARD)
 
 +++*+++ Latency is the total latency from the point at which sampling started on that instruction, rather
 than only the execution latency.
@@ -220,6 +221,31 @@ Common errors
 
    Increase sampling interval (see above)
 
+PMU events
+~~~~~~~~~~
+
+SPE has events that can be counted on core PMUs. These are prefixed with
+SAMPLE_, for example SAMPLE_POP, SAMPLE_FEED, SAMPLE_COLLISION and
+SAMPLE_FEED_BR.
+
+These events will only count when an SPE event is running on the same core that
+the PMU event is opened on, otherwise they read as 0. There are various ways to
+ensure that the PMU event and SPE event are scheduled together depending on the
+way the event is opened. For example opening both events as per-process events
+on the same process, although it's not guaranteed that the PMU event is enabled
+first when context switching. For that reason it may be better to open the PMU
+event as a systemwide event and then open SPE on the process of interest.
+
+Discard mode
+~~~~~~~~~~~~
+
+SPE related (SAMPLE_* etc) core PMU events can be used without the overhead of
+collecting sample data if discard mode is supported (optional from Armv8.6).
+First run a system wide SPE session (or on the core of interest) using options
+to minimize output. Then run perf stat:
+
+  perf record -e arm_spe/discard/ -a -N -B --no-bpf-event -o - > /dev/null &
+  perf stat -e SAMPLE_FEED_LD
 
 SEE ALSO
 --------