Re: [Xen-devel] [PATCH V3 16/29] x86/vvtd: decode interrupt attribute from IRTE

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Sep 21, 2017 at 11:01:57PM -0400, Lan Tianyu wrote:
> From: Chao Gao <chao.gao@xxxxxxxxx>
> 
> Without interrupt remapping, interrupt attributes can be extracted from
> msi message or IOAPIC RTE. However, with interrupt remapping enabled,
> the attributes are enclosed in the associated IRTE. This callback is
> for cases in which the caller wants to acquire interrupt attributes, for
> example:
> 1. vioapic_get_vector(). With vIOMMU, the RTE may don't contain vector.
                                                    ^ not
> 2. perform EOI which is always based on the interrupt vector.
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
> ---
> v3:
>  - add example cases in which we will use this function.
> ---
>  xen/drivers/passthrough/vtd/vvtd.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/drivers/passthrough/vtd/vvtd.c 
> b/xen/drivers/passthrough/vtd/vvtd.c
> index 90c00f5..5e22ace 100644
> --- a/xen/drivers/passthrough/vtd/vvtd.c
> +++ b/xen/drivers/passthrough/vtd/vvtd.c
> @@ -516,6 +516,26 @@ static int vvtd_handle_irq_request(struct domain *d,
>                           irte.remap.tm);
>  }
>  
> +static int vvtd_get_irq_info(struct domain *d,
> +                             struct arch_irq_remapping_request *irq,
> +                             struct arch_irq_remapping_info *info)
> +{
> +    int ret;
> +    struct iremap_entry irte;
> +    struct vvtd *vvtd = domain_vvtd(d);

I've realized that some of the helpers perform a if (!vvtd ) return
check, while others don't (like this one). Are some handlers expected
to be called without a vIOMMU? If so it would be good to list them
clearly.

Thanks, Roger.

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