Print out the expected vs. actual count of the Top-Down Slots event on
failure in the Intel PMU counters test. GUEST_ASSERT() only expands
constants/macros, i.e. only prints the value of the expected count, which
makes it difficult to debug and triage failures.
Link: https://lore.kernel.org/r/20250117234204.2600624-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Now that validation of event count is tied to hardware support for event,
and not to guest support for an event, drop the unused "event" parameter
from the various helpers.
No functional change intended.
Link: https://lore.kernel.org/r/20250117234204.2600624-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Drop the local "nr_arch_events" in the Intel PMU counters test as the test
asserts that "nr_arch_events <= NR_INTEL_ARCH_EVENTS", and then sets
nr_arch_events to the max of the two. I.e. nr_arch_events is guaranteed
to be NR_INTEL_ARCH_EVENTS for the meat of the test, just use
NR_INTEL_ARCH_EVENTS directly.
No functional change intended.
Link: https://lore.kernel.org/r/20250117234204.2600624-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
In the Intel PMU counters test, only validate the counts for architectural
events that are supported in hardware. If an arch event isn't supported,
the event selector may enable a completely different event, and thus the
logic for the expected count is bogus.
This fixes test failures on pre-Icelake systems due to the encoding for
the architectural Top-Down Slots event corresponding to something else
(at least on the Skylake family of CPUs).
Note, validation relies on *hardware* support, not KVM support and not
guest support. Architectural events are all about enumerating the event
selector encoding; lack of enumeration for an architectural event doesn't
mean the event itself is unsupported, i.e. the event should still count as
expected even if KVM and/or guest CPUID doesn't enumerate the event as
being "architectural".
Note #2, it's desirable to _program_ the architectural event encoding even
if hardware doesn't support the event. The count can't be validated when
the event is fully enabled, but KVM should still let the guest program the
event selector, and the PMC shouldn't count if the event is disabled.
Fixes: 4f1bd6b160 ("KVM: selftests: Test Intel PMU architectural events on gp counters")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202501141009.30c629b4-lkp@intel.com
Debugged-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20250117234204.2600624-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Wrap PMU counter test's array of Intel architectrual in a helper function
so that the events can be queried in multiple locations. Add a comment to
explain the need for a wrapper.
No functional change intended.
Link: https://lore.kernel.org/r/20250117234204.2600624-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
In the PMU counters test, add a data load in the measured loop and target
the data with CLFLUSH{OPT} in order to (try to) guarantee the loop
generates LLC misses and fills. Per the SDM, some hardware prefetchers
are allowed to omit relevant PMU events, and Emerald Rapids (and possibly
Sapphire Rapids) appears to have gained an instruction prefetcher that
bypasses event counts. E.g. the test will consistently fail on EMR CPUs,
but then pass with seemingly benign changes to the code.
The event count includes speculation and cache line fills due to the
first-level cache hardware prefetcher, but may exclude cache line fills
due to other hardware-prefetchers.
Generate a data load as a last ditch effort to preserve the (minimal) test
coverage for LLC references and misses.
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20241127235627.4049619-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Fix goofs in PMU counter test's assertion macros where the macros
unintentionally reference variables in the parent scope. The code "works"
as-is purely by accident, as all users define a variable with the correct
name (and usage).
Fixes: cd34fd8c75 ("KVM: selftests: Test PMC virtualization with forced emulation")
Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20240918205319.3517569-2-coltonlewis@google.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Use the kernel's canonical $(ARCH) paths instead of the raw target triple
for KVM selftests directories. KVM selftests are quite nearly the only
place in the entire kernel that using the target triple for directories,
tools/testing/selftests/drivers/s390x being the lone holdout.
Using the kernel's preferred nomenclature eliminates the minor, but
annoying, friction of having to translate to KVM's selftests directories,
e.g. for pattern matching, opening files, running selftests, etc.
Opportunsitically delete file comments that reference the full path of the
file, as they are obviously prone to becoming stale, and serve no known
purpose.
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20241128005547.4077116-16-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-12-18 14:15:04 -08:00
Renamed from tools/testing/selftests/kvm/x86_64/pmu_counters_test.c (Browse further)
