Re: [PATCH 1/8] KVM: Add MSI_ACTION flag for assigned irq

[Marcelo Tosatti <mtosatti@redhat.com>]

On Tue, Dec 23, 2008 at 04:00:24PM +0800, Sheng Yang wrote:
> For MSI disable feature later.
> 
> Notice I changed ABI here, but due to no userspace patch, I think it's OK.
> 
> Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> ---
>  include/linux/kvm.h |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index ef7f98e..5b965f6 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -544,6 +544,7 @@ struct kvm_assigned_irq {
>  
>  #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
>  
> -#define KVM_DEV_IRQ_ASSIGN_ENABLE_MSI	(1 << 0)
> +#define KVM_DEV_IRQ_ASSIGN_MSI_ACTION	(1 << 0)
> +#define KVM_DEV_IRQ_ASSIGN_ENABLE_MSI	(1 << 1)

This is a little confusing. KVM_DEV_IRQ_ASSIGN_MSI_ACTION is assigned
from userspace, and in the patchset used in conjunction with msi2intx
which is a module parameter.

Is there anything that blocks control of msi2intx translate behaviour
from userspace?

Perhaps add a KVM_DEV_IRQ_UNASSIGN ioctl, and pass the desired
guest/host irq types on the IRQ_ASSIGN ioctl, thus removing some of the
kernel complexity.