Like Xu cf52de619c KVM: x86/pmu: Avoid using PEBS perf_events for normal counters ...

The check logic in the pmc_resume_counter() to determine whether
a perf_event is reusable is partial and flawed, especially when it
comes to a pseudocode sequence (contrived, but valid) like:

  - enabling a counter and its PEBS bit
  - enable global_ctrl
  - run workload
  - disable only the PEBS bit, leaving the global_ctrl bit enabled

In this corner case, a perf_event created for PEBS can be reused by
a normal counter before it has been released and recreated, and when this
normal counter overflows, it triggers a PEBS interrupt (precise_ip != 0).

To address this issue, reprogram all affected counters when PEBS_ENABLE
change and reuse a counter if and only if PEBS exactly matches precise.

Fixes: 79f3e3b583 ("KVM: x86/pmu: Reprogram PEBS event to emulate guest PEBS counter")
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20220831085328.45489-4-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

2022-09-28 12:47:22 -07:00

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