CVE-2025-38322

In the Linux kernel, the following vulnerability has been resolved:

perf/x86/intel: Fix crash in icl_update_topdown_event()

The perf_fuzzer found a hard-lockup crash on a RaptorLake machine:

  Oops: general protection fault, maybe for address 0xffff89aeceab400: 0000
  CPU: 23 UID: 0 PID: 0 Comm: swapper/23
  Tainted: [W]=WARN
  Hardware name: Dell Inc. Precision 9660/0VJ762
  RIP: 0010:native_read_pmc+0x7/0x40
  Code: cc e8 8d a9 01 00 48 89 03 5b cd cc cc cc cc 0f 1f ...
  RSP: 000:fffb03100273de8 EFLAGS: 00010046
  ....
  Call Trace:
    <TASK>
    icl_update_topdown_event+0x165/0x190
    ? ktime_get+0x38/0xd0
    intel_pmu_read_event+0xf9/0x210
    __perf_event_read+0xf9/0x210

CPUs 16-23 are E-core CPUs that don't support the perf metrics feature.
The icl_update_topdown_event() should not be invoked on these CPUs.

It's a regression of commit:

  f9bdf1f95339 ("perf/x86/intel: Avoid disable PMU if !cpuc->enabled in sample read")

The bug introduced by that commit is that the is_topdown_event() function
is mistakenly used to replace the is_topdown_count() call to check if the
topdown functions for the perf metrics feature should be invoked.

Fix it.