Currently, VFIO takes a free-then-request-irq way to do interrupt affinity setting and masking/unmasking for a VM with device passthru via VFIO. Sometimes it only changes the cookie data of irqaction or even changes nothing. The free-then-request-irq not only adds more latency, but also increases the risk of losing interrupt, which may lead to a VM hang forever in waiting for IO completion
This patchset solved the issue by: Patch 2 introduces irq_update_devid() to only update dev_id of irqaction Patch 3 make use of this function and optimize irq operations in VFIO changes from v5: - Patch 3: remove an error log to avoid potential DDoS attacking _ Patch 3: fix typo in comment changes from v4: - Patch 3: follow the previous behavior to disable interrupt on error path - Patch 3: do irqbypass registration before update or free the interrupt - Patch 3: add more comments changes from v3: - Patch 2: rename the new function to irq_update_devid() - Patch 2: use disbale_irq() to avoid a twist for threaded interrupt - ALL: amend commit messages and code comments changes from v2: - reformat to avoid quoted string split across lines and etc. changes from v1: - add Patch 1 to enhance error recovery etc. in free irq per tglx's comments - enhance error recovery code and debugging info in irq_update_devid - use __must_check in external referencing of this function - use EXPORT_SYMBOL_GPL for irq_update_devid - reformat code of patch 3 for better readability Ben Luo (3): genirq: enhance error recovery code in free irq genirq: introduce irq_update_devid() vfio/pci: make use of irq_update_devid() and optimize irq ops drivers/vfio/pci/vfio_pci_intrs.c | 118 ++++++++++++++++++++++++++------------ include/linux/interrupt.h | 3 + kernel/irq/manage.c | 105 +++++++++++++++++++++++++++++---- 3 files changed, 177 insertions(+), 49 deletions(-) -- 1.8.3.1
