linux-kernel - Re: [PATCH v2 8/8] KVM: arm/arm64: register DEOI irq bypass consumer on ARM/ARM64

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Date:   Fri, 21 Jul 2017 15:25:06 +0200
From:   Christoffer Dall <cdall@...aro.org>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     eric.auger.pro@...il.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
        alex.williamson@...hat.com, b.reynal@...tualopensystems.com,
        pbonzini@...hat.com, marc.zyngier@....com,
        christoffer.dall@...aro.org, drjones@...hat.com, wei@...hat.com
Subject: Re: [PATCH v2 8/8] KVM: arm/arm64: register DEOI irq bypass consumer
 on ARM/ARM64

On Thu, Jun 15, 2017 at 02:52:40PM +0200, Eric Auger wrote:
> This patch selects IRQ_BYPASS_MANAGER and HAVE_KVM_IRQ_BYPASS
> configs for ARM/ARM64.
> 
> kvm_arch_has_irq_bypass() now is implemented and returns true.
> As a consequence the irq bypass consumer will be registered for
> ARM/ARM64 with Direct EOI/IRQ forwarding callbacks:
> 
> - stop/start: halt/resume guest execution
> - add/del_producer: set/unset forwarding/DEOI at vgic/irqchip level
> 
> The consumer currently only works with a VFIO_PLATFORM producer.
> In other cases, start/stop do nothing and return without error
> to avoid outputting a spurious warning.
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> 
> ---
> 
> v1 -> v2:
> - check the type of the producer to avoid attachement with VFIO-PCI
>   dummy MSI producer
> ---
>  arch/arm/kvm/Kconfig   |  3 +++
>  arch/arm64/kvm/Kconfig |  3 +++
>  virt/kvm/arm/arm.c     | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 54 insertions(+)
> 
> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
> index 90d0176..4e2b192 100644
> --- a/arch/arm/kvm/Kconfig
> +++ b/arch/arm/kvm/Kconfig
> @@ -3,6 +3,7 @@
>  #
>  
>  source "virt/kvm/Kconfig"
> +source "virt/lib/Kconfig"
>  
>  menuconfig VIRTUALIZATION
>  	bool "Virtualization"
> @@ -35,6 +36,8 @@ config KVM
>  	select HAVE_KVM_IRQCHIP
>  	select HAVE_KVM_IRQ_ROUTING
>  	select HAVE_KVM_MSI
> +	select IRQ_BYPASS_MANAGER
> +	select HAVE_KVM_IRQ_BYPASS
>  	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
>  	---help---
>  	  Support hosting virtualized guest machines.
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 52cb7ad..7e0d6e6 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -3,6 +3,7 @@
>  #
>  
>  source "virt/kvm/Kconfig"
> +source "virt/lib/Kconfig"
>  
>  menuconfig VIRTUALIZATION
>  	bool "Virtualization"
> @@ -35,6 +36,8 @@ config KVM
>  	select HAVE_KVM_MSI
>  	select HAVE_KVM_IRQCHIP
>  	select HAVE_KVM_IRQ_ROUTING
> +	select IRQ_BYPASS_MANAGER
> +	select HAVE_KVM_IRQ_BYPASS
>  	---help---
>  	  Support hosting virtualized guest machines.
>  	  We don't support KVM with 16K page tables yet, due to the multiple
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 3417e18..58871f8 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -27,6 +27,8 @@
>  #include <linux/mman.h>
>  #include <linux/sched.h>
>  #include <linux/kvm.h>
> +#include <linux/kvm_irqfd.h>
> +#include <linux/irqbypass.h>
>  #include <trace/events/kvm.h>
>  #include <kvm/arm_pmu.h>
>  
> @@ -1420,6 +1422,52 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr)
>  	return NULL;
>  }
>  
> +bool kvm_arch_has_irq_bypass(void)
> +{
> +	return true;
> +}
> +
> +int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
> +				      struct irq_bypass_producer *prod)
> +{
> +	struct kvm_kernel_irqfd *irqfd =
> +		container_of(cons, struct kvm_kernel_irqfd, consumer);
> +
> +	if (prod->type != IRQ_BYPASS_VFIO_PLATFORM)
> +		return 0;
> +
> +	return kvm_vgic_set_forwarding(irqfd->kvm, prod->irq,
> +				       irqfd->gsi + VGIC_NR_PRIVATE_IRQS);
> +}
> +void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
> +				      struct irq_bypass_producer *prod)
> +{
> +	struct kvm_kernel_irqfd *irqfd =
> +		container_of(cons, struct kvm_kernel_irqfd, consumer);
> +
> +	if (prod->type != IRQ_BYPASS_VFIO_PLATFORM)
> +		return;
> +
> +	kvm_vgic_unset_forwarding(irqfd->kvm, prod->irq,
> +				  irqfd->gsi + VGIC_NR_PRIVATE_IRQS);
> +}
> +
> +void kvm_arch_irq_bypass_stop(struct irq_bypass_consumer *cons)
> +{
> +	struct kvm_kernel_irqfd *irqfd =
> +		container_of(cons, struct kvm_kernel_irqfd, consumer);
> +
> +	kvm_arm_halt_guest(irqfd->kvm);
> +}
> +
> +void kvm_arch_irq_bypass_start(struct irq_bypass_consumer *cons)
> +{
> +	struct kvm_kernel_irqfd *irqfd =
> +		container_of(cons, struct kvm_kernel_irqfd, consumer);
> +
> +	kvm_arm_resume_guest(irqfd->kvm);
> +}
> +
>  /**
>   * Initialize Hyp-mode and memory mappings on all CPUs.
>   */
> -- 
> 2.5.5

Nit: I'm wondering if this should go in a different file, like
virt/kvm/arm/irqbypass.c, or virt/kvm/arm/vgic/vgic-irqbypass.c ?

Thanks,
-Christoffer