This series allows to set ARM IRQ forwarding between a VFIO platform device physical IRQ and a guest virtual IRQ. the link now is coordinated by the IRQ bypass manager. This kernel integration deprecates kvm-vfio approach (https://lkml.org/lkml/2015/4/13/353). Some rationale about that change can be found in IRQ bypass manager thread: https://lkml.org/lkml/2015/6/29/268 The principle is the VFIO platform driver registers an IRQ bypass 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. The series transforms the vfio platform driver into an IRQ bypass manager producer and implements the KVM IRQ bypass callbacks. 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- [RFC v2 0/6] IRQ bypass manager and irqfd consumer including Alex's IRQ bypass manager sent by email (https://lkml.org/lkml/2015/6/29/268) http://www.spinics.net/lists/kernel/msg2026011.html 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-v2.1 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 History: v1 -> v2: - irq bypass manager and irqfd consumer moved in a separate patch - kvm_arm_[halt,resume]_guest moved in a separate patch - remove VFIO external functions since we do not need them anymore - apply container_of strategy advised by Paolo. Only active field remains and discussions will tell whether we get rid of it. - renamed kvm_arch functions - kvm-vfio v6 -> RFC v1 based on IRQ bypass manager see previous history in https://lkml.org/lkml/2015/4/13/353). Best Regards Eric Eric Auger (9): VFIO: platform: registration of a dummy IRQ bypass producer VFIO: platform: test forwarded state when selecting IRQ handler VFIO: platform: single handler using function pointer VFIO: platform: add vfio_platform_set_automasked VFIO: platform: add vfio_platform_is_active irq: bypass: add active field on producer side VFIO: platform: add irq bypass producer management KVM: arm/arm64: vgic: forwarding control KVM: arm/arm64: implement IRQ bypass consumer functions arch/arm/kvm/Kconfig | 1 + arch/arm/kvm/arm.c | 40 ++++++ arch/arm64/kvm/Kconfig | 1 + drivers/vfio/platform/vfio_platform_irq.c | 120 +++++++++++++++- drivers/vfio/platform/vfio_platform_private.h | 3 + include/kvm/arm_vgic.h | 7 + include/linux/irqbypass.h | 2 + virt/kvm/arm/vgic.c | 195 ++++++++++++++++++++++++++ 8 files changed, 362 insertions(+), 7 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
