This series allows to optimize the deactivation of virtual interrupts associated to vfio platform device interrupts. This is a revival of "[PATCH v4 00/13] ARM IRQ forward control based on IRQ bypass manager" (https://lkml.org/lkml/2015/11/19/351) whose development was stalled due to dependency on new VGIC design and drop of priority. Without that optimization the deactivation of the physical IRQ is performed by the host. Also for level sensitive interrupts, The VFIO driver disables the physical IRQ. The deactivation of the virtual IRQ by the guest is trapped and the physical IRQ gets re-enabled at that time. The ARM GIC supports direct EOI for virtual interrupts directly mapped to physical interrupts. When this mode is set, the host does not deactivate the physical interrupt anymore, but simply drops the interrupt priority on EOI. When the guest deactivates the virtual IRQ, the GIC automatically deactivates the physical IRQ. This avoids a world switch on deactivation. This series sets direct EOI mode on ARM/ARM64 for vfio platform interrupts. This relies on a negotiation between the vfio platform driver and KVM/irqfd though the irq bypass manager. The setup sequence is: preamble: - disable the physical IRQ - halt guest execution forwarding setting: - program the VFIO driver for forwarding (select the right physical interrupt handler) - program the VGIC and IRQCHIP for forwarding postamble: - resume guest execution - enable the physical IRQ When destroying the optimized path the following sequence is executed: - preamble - unset forwarding at VGIC and IRQCHIP level - unset forwarding at VFIO level - postamble The injection still is based on irqfd triggering. For level sensitive interrupts though, the resamplefd is not triggered anymore since deactivation is not trapped by KVM. This was tested with: - AMD Seattle xgmac platform device assignment - Also MSI non regression was tested The series can be fount at: https://github.com/eauger/linux/tree/v4.12-rc5-deoi-v2 It is based on 4.12-rc5 Best Regards Eric History: v1 -> v2: - drop VFIO-PCI INTx support due to shared interrupt incompatibility - introduce a producer type - restructured kvm_vgic_[set|unset]_forwarding for reuse in forwarding setting Eric Auger (8): VFIO: platform: Differentiate auto-masking from user masking VFIO: platform: Introduce direct EOI interrupt handler VFIO: platform: Direct EOI irq bypass for ARM/ARM64 KVM: arm/arm64: vgic: restructure kvm_vgic_(un)map_phys_irq KVM: arm/arm64: vgic: Handle mapped level sensitive SPIs KVM: arm/arm64: vgic: Implement forwarding setting virt: irqbypass: Add a type field to the irqbypass producer KVM: arm/arm64: register DEOI irq bypass consumer on ARM/ARM64 arch/arm/kvm/Kconfig | 3 + arch/arm64/kvm/Kconfig | 3 + drivers/vfio/pci/vfio_pci_intrs.c | 1 + drivers/vfio/platform/Kconfig | 5 + drivers/vfio/platform/Makefile | 2 +- drivers/vfio/platform/vfio_platform_irq.c | 60 ++++++--- drivers/vfio/platform/vfio_platform_irq_bypass.c | 119 ++++++++++++++++ drivers/vfio/platform/vfio_platform_private.h | 30 ++++- include/kvm/arm_vgic.h | 13 +- include/linux/irqbypass.h | 7 + virt/kvm/arm/arch_timer.c | 24 +--- virt/kvm/arm/arm.c | 48 +++++++ virt/kvm/arm/vgic/vgic.c | 164 ++++++++++++++++++++--- virt/kvm/arm/vgic/vgic.h | 7 +- 14 files changed, 425 insertions(+), 61 deletions(-) create mode 100644 drivers/vfio/platform/vfio_platform_irq_bypass.c -- 2.5.5
