This started out as a simple change to sort the (up to 300 element)
PMU filtered event list and to use binary search rather than linear
search to see if an event is in the list.
I thought it would be nice to add a directed test for the PMU event
filter, and that's when things got complicated. The Intel side was
fine, but the AMD side was a bit ugly, until I did a few
refactorings. Imagine my dismay when I discovered that the PMU event
filter works fine on the AMD side, but that fundamental PMU
virtualization is broken.
I'm not referring to erratum 1292, though that throws even more
brokenness into the mix. Apparently, a #VMEXIT counts as a "retired
branch instruction." The Zen family PPRs do say, "This includes all
types of architectural control flow changes, including exceptions and
interrupts," so apparently everything is working as intended. However,
this means that if the hypervisor doesn't adjust the counts, the
results are not only different from bare metal, but they are
non-deterministic as well (because a physical interrupt can occur at
any time and bump the count up).
v1 -> v2
* Drop the check for "AMDisbetter!" in is_amd_cpu() [David Dunn]
* Drop the call to cpuid(0, 0) that fed the original check for
CPU vendor string "AuthenticAMD" in vm_compute_max_gfn().
* Simplify the inline asm in the selftest by using the compound literal
for both input & output.
v2 -> v3 [only the selftest is modified]
* Literally copy ARCH_PERFMON_EVENTSEL_{OS,ENABLE} from perf_event.h,
rather than defining semantic equivalents.
* Copy cpuid10_e[ab]x from perf_event.h for improved readability of the
code that checks CPUID.0AH.
* Preface the guest code with a PMU sanity check, so that the test will
skip rather than fail if the PMU is non-functional (disabled by module
parameter, unimplemented or disabled by parent hypervisor, &c).
[David Dunn]
* Refactor and rename the Intel and AMD PMU checks.
* Use the is_amd_cpu() code from an earlier commit in the series (as well
as the is_intel_cpu() code).
* Add a check for at least one general-purpose counter on the Intel side.
* Change each of the Zen family/model checks to include the sixteen model
number range specified in AMD's "Revision Guide" for each generation of CPU,
rather than the single model number specified in the associated PPRs.
Jim Mattson (6):
KVM: x86/pmu: Use binary search to check filtered events
selftests: kvm/x86: Parameterize the CPUID vendor string check
selftests: kvm/x86: Introduce is_amd_cpu()
selftests: kvm/x86: Export x86_family() for use outside of processor.c
selftests: kvm/x86: Introduce x86_model()
selftests: kvm/x86: Add test for KVM_SET_PMU_EVENT_FILTER
arch/x86/kvm/pmu.c | 30 +-
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/x86_64/processor.h | 18 +
.../selftests/kvm/lib/x86_64/processor.c | 40 +-
.../kvm/x86_64/pmu_event_filter_test.c | 437 ++++++++++++++++++
6 files changed, 492 insertions(+), 35 deletions(-)
create mode 100644 tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
--
2.34.1.703.g22d0c6ccf7-goog
