Re: [PATCH v4 4/5] KVM: introduce kvm_arch functions for IRQ bypass

From: Alex Williamson
Date: Fri Aug 07 2015 - 16:09:23 EST


On Mon, 2015-08-03 at 19:20 +0200, Eric Auger wrote:
> This patch introduces
> - kvm_arch_irq_bypass_add_producer
> - kvm_arch_irq_bypass_del_producer
> - kvm_arch_irq_bypass_stop
> - kvm_arch_irq_bypass_start
>
> They make possible to specialize the KVM IRQ bypass consumer in
> case CONFIG_KVM_HAVE_IRQ_BYPASS is set.
>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
>
> ---
>
> v2 -> v3 (Feng Wu):
> - use 'kvm_arch_irq_bypass_start' instead of 'kvm_arch_irq_bypass_resume'
> - Remove 'kvm_arch_irq_bypass_update', which is not needed to be
> a irqbypass callback per Alex's comments.
> - Make kvm_arch_irq_bypass_add_producer return 'int'
>
> v1 -> v2:
> - use CONFIG_KVM_HAVE_IRQ_BYPASS instead CONFIG_IRQ_BYPASS_MANAGER
> - rename all functions according to Paolo's proposal
> - add kvm_arch_irq_bypass_update according to Feng's need
> ---
> include/linux/kvm_host.h | 33 +++++++++++++++++++++++++++++++++
> virt/kvm/Kconfig | 3 +++
> 2 files changed, 36 insertions(+)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 05e99b8..84b5feb 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -24,6 +24,7 @@
> #include <linux/err.h>
> #include <linux/irqflags.h>
> #include <linux/context_tracking.h>
> +#include <linux/irqbypass.h>
> #include <asm/signal.h>
>
> #include <linux/kvm.h>
> @@ -1151,5 +1152,37 @@ static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val)
> {
> }
> #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */
> +
> +#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
> +
> +int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *,
> + struct irq_bypass_producer *);
> +void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *,
> + struct irq_bypass_producer *);
> +void kvm_arch_irq_bypass_stop(struct irq_bypass_consumer *);
> +void kvm_arch_irq_bypass_start(struct irq_bypass_consumer *);
> +
> +#else

Do we really need static inline stubs? When would they get used? How
would they work since we call them via function pointers?

> +
> +static inline int kvm_arch_irq_bypass_add_producer(
> + struct irq_bypass_consumer *cons,
> + struct irq_bypass_producer *prod)
> +{
> + return -1;

No reason not to stick with standard errno values, is there? -EINVAL
Thanks,

Alex

> +}
> +static inline void kvm_arch_irq_bypass_del_producer(
> + struct irq_bypass_consumer *cons,
> + struct irq_bypass_producer *prod)
> +{
> +}
> +static inline void kvm_arch_irq_bypass_stop(
> + struct irq_bypass_consumer *cons)
> +{
> +}
> +static inline void kvm_arch_irq_bypass_start(
> + struct irq_bypass_consumer *cons)
> +{
> +}
> +#endif /* CONFIG_HAVE_KVM_IRQ_BYPASS */
> #endif
>
> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
> index e2c876d..9f8014d 100644
> --- a/virt/kvm/Kconfig
> +++ b/virt/kvm/Kconfig
> @@ -47,3 +47,6 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
> config KVM_COMPAT
> def_bool y
> depends on COMPAT && !S390
> +
> +config HAVE_KVM_IRQ_BYPASS
> + bool



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