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

[Alex Williamson]

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@xxxxxxxxxx>
> 
> ---
> 
> 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@xxxxxxxxxx>
> + *
> + * 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;
> +}



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