This series allows to set ARM IRQ forwarding between a VFIO platform device physical IRQ and a guest virtual IRQ.
The setting is coordinated by the prototype IRQ bypass manager. This kernel integration seems now prefered to previous kvm-vfio device user api: - [RFC v6 00/16] KVM-VFIO IRQ forward control, https://lkml.org/lkml/2015/4/13/353). Some rationale can be found in IRQ bypass manager thread: https://lkml.org/lkml/2015/6/29/268 The principle is the VFIO platform driver registers a producer struct on VFIO_IRQ_SET_ACTION_TRIGGER while KVM irqfd registers a consumer struct on the irqfd assignment. This leads to a handshake based on the eventfd context (used as token) match. When either of the producer/consumer module disappears, this leads to an unregistration and the link is disconnected. Structure of the series: [1-6] Modifications in the VFIO (platform) driver to prepare for dynamic switch between automasked/masked mode [7-8] Introduce halt/resume guest capability [9] irq bypass manager proto as sent by Alex [10-17] Adaptations to support forwarding on top of IRQ bypass manager Dependencies: 1- [PATCH 00/10] arm/arm64: KVM: Active interrupt state switching for shared devices (http://www.spinics.net/lists/kvm/msg117411.html) 2- RFC "ARM: Forwarding physical interrupts to a guest VM" (http://lwn.net/Articles/603514/) 3- IRQ bypass manager proto: https://lkml.org/lkml/2015/6/29/268 4- [RFC v2 0/4] chip/vgic adaptations for forwarded irq http://lists.infradead.org/pipermail/linux-arm-kernel/2015-February/323183.html All those pieces can be found at: https://git.linaro.org/people/eric.auger/linux.git/shortlog/refs/heads/v4.2-rc1-bypass-fwd More backgroung on ARM IRQ forwarding in the text below and at http://www.linux-kvm.org/images/a/a8/01x04-ARMdevice.pdf. A forwarded IRQ is deactivated by the guest and not by the host. When the guest deactivates the associated virtual IRQ, the interrupt controller automatically completes the physical IRQ. Obviously this requires some HW support in the interrupt controller. This is the case for ARM GICv2. The direct benefit is that, for a level sensitive IRQ, a VM exit can be avoided on forwarded IRQ completion. When the IRQ is forwarded, the VFIO platform driver does not need to mask the physical IRQ anymore before signaling the eventfd. Indeed genirq lowers the running priority, enabling other physical IRQ to hit except that one. Besides, the injection still is based on irqfd triggering. The only impact on irqfd process is resamplefd is not called anymore on virtual IRQ completion since deactivation is not trapped by KVM. This was tested on Calxeda Midway, assigning the xgmac main IRQ kvm-vfio v6 -> rfc based on IRQ bypass manager see previous history in https://lkml.org/lkml/2015/4/13/353). Best Regards Eric Alex Williamson (1): bypass: IRQ bypass manager proto by Alex Eric Auger (16): VFIO: platform: test forwarded state when selecting IRQ handler VFIO: platform: single handler using function pointer VFIO: Introduce vfio_device_external_ops VFIO: pci: initialize vfio_device_external_ops VFIO: platform: implement vfio_device_external_ops callbacks VFIO: add vfio_external_{mask|is_active|set_automasked} KVM: arm: rename pause into power_off kvm: arm/arm64: implement kvm_arm_[halt,resume]_guest KVM: arm: select IRQ_BYPASS_MANAGER VFIO: platform: select IRQ_BYPASS_MANAGER irq: bypass: Extend skeleton for ARM forwarding control KVM: introduce kvm_arch functions for IRQ bypass KVM: arm/arm64: vgic: forwarding control KVM: arm/arm64: implement IRQ bypass consumer functions KVM: eventfd: add irq bypass consumer management VFIO: platform: add irq bypass producer management arch/arm/include/asm/kvm_host.h | 5 +- arch/arm/kvm/Kconfig | 1 + arch/arm/kvm/arm.c | 60 +++++++- arch/arm/kvm/psci.c | 10 +- arch/arm64/include/asm/kvm_host.h | 3 + arch/x86/kvm/Kconfig | 1 + drivers/vfio/pci/Kconfig | 1 + drivers/vfio/pci/vfio_pci.c | 1 + drivers/vfio/pci/vfio_pci_intrs.c | 6 + drivers/vfio/platform/Kconfig | 1 + drivers/vfio/platform/vfio_platform_common.c | 9 ++ drivers/vfio/platform/vfio_platform_irq.c | 160 ++++++++++++++++++++- drivers/vfio/platform/vfio_platform_private.h | 14 ++ drivers/vfio/vfio.c | 39 ++++++ include/kvm/arm_vgic.h | 7 + include/linux/irqbypass.h | 43 ++++++ include/linux/kvm_host.h | 27 ++++ include/linux/vfio.h | 34 +++++ kernel/irq/Kconfig | 3 + kernel/irq/Makefile | 1 + kernel/irq/bypass.c | 156 +++++++++++++++++++++ virt/kvm/arm/vgic.c | 195 ++++++++++++++++++++++++++ virt/kvm/eventfd.c | 20 +++ 23 files changed, 778 insertions(+), 19 deletions(-) create mode 100644 include/linux/irqbypass.h create mode 100644 kernel/irq/bypass.c -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
