[PATCH v3 8/8] KVM: arm: kvm-vfio: forwarding control

Alex Williamson
2014-11-24T20:56:26Z

On Sun, 2014-11-23 at 19:36 +0100, Eric Auger wrote:
> This patch sets __KVM_HAVE_ARCH_KVM_VFIO_FORWARD and implements
> kvm_arch_vfio_set_forward for ARM.
>
> As a result the KVM-VFIO device now allows to forward/unforward a
> VFIO device IRQ on ARM.
>
> kvm_arch_vfio_set_forward programs both genirq and the VGIC to control
> where the physical IRQ deactivation is initiated.
> - forwarded case: deactivation is initiated by the guest; when it
> completes the virtual IRQ, the GIC automatically deactivates the
> physical IRQ.
> - not forwarded case: the physical IRQ deactivation is handled by the host
>
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
>
> ---
>
> v2 -> v3:
> - renaming of kvm_arch_set_fwd_state into kvm_arch_vfio_set_forward
> - takes a bool arg instead of kvm_fwd_irq_action enum
> - removal of KVM_VFIO_IRQ_CLEANUP
> - platform device check now happens here
> - more precise errors returned
> - irq_eoi handled externally to this patch (VGIC)
> - correct enable_irq bug done twice
> - reword the commit message
> - correct check of platform_bus_type
> - use raw_spin_lock_irqsave and check the validity of the handler
> ---
> arch/arm/include/asm/kvm_host.h | 2 +
> arch/arm/kvm/Makefile | 2 +-
> arch/arm/kvm/kvm_vfio_arm.c | 101 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 104 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm/kvm/kvm_vfio_arm.c
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index bca5b79..447f90c 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -27,6 +27,8 @@
> #include <asm/fpstate.h>
> #include <kvm/arm_arch_timer.h>
>
> +#define __KVM_HAVE_ARCH_KVM_VFIO_FORWARD
> +
> #if defined(CONFIG_KVM_ARM_MAX_VCPUS)
> #define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS
> #else
> diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
> index ea1fa76..26a5a42 100644
> --- a/arch/arm/kvm/Makefile
> +++ b/arch/arm/kvm/Makefile
> @@ -19,7 +19,7 @@ kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o $(KVM)/vf
>
> obj-y += kvm-arm.o init.o interrupts.o
> obj-y += arm.o handle_exit.o guest.o mmu.o emulate.o reset.o
> -obj-y += coproc.o coproc_a15.o coproc_a7.o mmio.o psci.o perf.o
> +obj-y += coproc.o coproc_a15.o coproc_a7.o mmio.o psci.o perf.o kvm_vfio_arm.o
> obj-$(CONFIG_KVM_ARM_VGIC) += $(KVM)/arm/vgic.o
> obj-$(CONFIG_KVM_ARM_VGIC) += $(KVM)/arm/vgic-v2.o
> obj-$(CONFIG_KVM_ARM_TIMER) += $(KVM)/arm/arch_timer.o
> diff --git a/arch/arm/kvm/kvm_vfio_arm.c b/arch/arm/kvm/kvm_vfio_arm.c
> new file mode 100644
> index 0000000..af2c501
> --- /dev/null
> +++ b/arch/arm/kvm/kvm_vfio_arm.c
> @@ -0,0 +1,101 @@
> +/*
> + * Copyright (C) 2014 Linaro Ltd.
> + * Authors: Eric Auger <eric.auger@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2, as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/file.h>
> +#include <linux/kvm_host.h>
> +#include <linux/list.h>
> +#include <linux/mutex.h>
> +#include <linux/vfio.h>
> +#include <linux/irq.h>
> +#include <asm/kvm_host.h>
> +#include <asm/kvm.h>
> +#include <linux/irq.h>
> +#include <linux/spinlock.h>
> +#include <linux/platform_device.h>
> +#include <linux/interrupt.h>
> +
> +/**
> + * kvm_arch_vfio_set_forward - Change the forward state of an IRQ
> + *
> + * @fwd_irq: handle to the forward irq struct
> + * @forward: target forwarding state
> + *
> + * If forward is true, programs genirq and VGIC so that physical IRQ
> + * deactivation ownership is transferred to the guest (using GIC HW feature).
> + * When forward is false, standard behavior is restored, ie. host
> + * deactivates the physical IRQ.
> + * returns:
> + * -EINVAL if the vfio device is not a platform device
> + * -ENOENT if the irq could not be identified
> + * -EBUSY if physical IRQ is in progress
> + * -ENOENT if the VGIC has a physical/virtual IRQ mapping that is not
> + * consistent with the request.
> + */
> +int kvm_arch_vfio_set_forward(struct kvm_fwd_irq *fwd_irq,
> + bool forward)
> +{
> + int hwirq;
> + int ret = -EBUSY;
> + struct irq_desc *desc;
> + struct irq_data *d;
> + struct platform_device *platdev;
> + struct device *dev = kvm_vfio_external_base_device(fwd_irq->vdev);

Just pass the dev

> + unsigned long flags;
> + /*
> + * We don't have to garantee the vcpu handle is non void since the

s/garantee/guarantee/

> + * vfio device holds a reference to the kvm struct
> + */
> + struct kvm_vcpu *vcpu = kvm_get_vcpu(fwd_irq->kvm, 0);
> +
> + if (dev->bus == &platform_bus_type) {
> + platdev = to_platform_device(dev);
> + hwirq = platform_get_irq(platdev, fwd_irq->index);
> + if (hwirq < 0)
> + return -EINVAL;
> + } else
> + return -ENOENT;
> + desc = irq_to_desc(hwirq);
> +
> + /*
> + * if VFIO handler is already set, forwarded state cannot be
> + * changed anymore
> + */
> + raw_spin_lock_irqsave(&desc->lock, flags);
> + if (desc->action)
> + goto end;
> +
> + d = &desc->irq_data;
> +
> + if (forward) {
> + irqd_set_irq_forwarded(d);
> + raw_spin_unlock_irqrestore(&desc->lock, flags);
> + ret = vgic_map_phys_irq(vcpu,
> + fwd_irq->gsi + VGIC_NR_PRIVATE_IRQS,
> + hwirq);
> + } else {
> + irqd_clr_irq_forwarded(d);
> + raw_spin_unlock_irqrestore(&desc->lock, flags);
> + ret = vgic_unmap_phys_irq(vcpu,
> + fwd_irq->gsi +
> + VGIC_NR_PRIVATE_IRQS,
> + hwirq);
> + }
> + return ret;
> +
> +end:
> + raw_spin_unlock_irqrestore(&desc->lock, flags);
> + return ret;
> +}