commit 98b42fd75f48491ba9c8714dbedb7166e6b8ba48
author Colin Downs-Razouk <colindr@google.com> Wed Jul 13 12:44:41 2022 -0700
committer crosvm LUCI <crosvm-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Jul 15 22:23:06 2022 +0000
tree 860cb02ce8041acf56acb65cd4769eccc3dded63
parent 53c7515c3f1d58a736bb0fba727693264549c5ac

devices: tsc: calibrate handle offline cores

If a core is offline, we will not be able to set the cpu affinity to
that core. The TSC calibration code attempts to determine the TSC offset
of all cores. Determining which cores are online requires parsing the
contents of /sys/devices/system/cpu/online on linux, and it's not clear
how to do it on Windows. Instead, the calibration code will treat errors
when calling set_cpu_affinity as legitimate reasons for a core to be
offline, and will exclude that core from the offset information in the
TscState. This will prevent the TSC sync mitigation logic from setting
any vpu's affinity to that core.

This also changes how number_of_logical_cores is implemented on linux,
to count the number of configured cores instead of the number of online
cores, which seems more correct.

BUG=b:230372694
TEST=added a new unittest, also ran unittests with an offline core

Change-Id: I12c187a7ca1dd06e25b396eaeae542628fdf563c
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3764280
Tested-by: Colin Downs-Razouk <colindr@google.com>
Commit-Queue: Colin Downs-Razouk <colindr@google.com>
Reviewed-by: Dennis Kempin <denniskempin@google.com>