iommu/vt-d: Support cpumask for IOMMU perfmon

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The perf subsystem assumes that all counters are by default per-CPU. So
the user space tool reads a counter from each CPU. However, the IOMMU
counters are system-wide and can be read from any CPU. Here we use a CPU
mask to restrict counting to one CPU to handle the issue. (with CPU
hotplug notifier to choose a different CPU if the chosen one is taken
off-line).

The CPU is exposed to /sys/bus/event_source/devices/dmar*/cpumask for
the user space perf tool.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20230128200428.1459118-6-kan.liang@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

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Kan Liang 2023-01-31 15:37:38 +08:00 • committed by Joerg Roedel

parent 7232ab8b89

commit 46284c6ceb

3 changed files with 114 additions and 8 deletions

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include/linux/cpuhotplug.h

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