iommu/vt-d: Add IOMMU perfmon overflow handler support
While enabled to count events and an event occurrence causes the counter value to increment and roll over to or past zero, this is termed a counter overflow. The overflow can trigger an interrupt. The IOMMU perfmon needs to handle the case properly. New HW IRQs are allocated for each IOMMU device for perfmon. The IRQ IDs are after the SVM range. In the overflow handler, the counter is not frozen. It's very unlikely that the same counter overflows again during the period. But it's possible that other counters overflow at the same time. Read the overflow register at the end of the handler and check whether there are more. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20230128200428.1459118-7-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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