Re: [PATCH ats_vtd v5 04/22] intel_iommu: do not consider wait_desc as an invalid descriptor

[Yi Liu]

On 2024/7/2 13:52, CLEMENT MATHIEU--DRIF wrote:
> From: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
>
> Signed-off-by: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
> Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>   hw/i386/intel_iommu.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 98996ededc..71cebe2fd3 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -3500,6 +3500,11 @@ static bool vtd_process_wait_desc(IntelIOMMUState *s, 
> VTDInvDesc *inv_desc)
>       } else if (inv_desc->lo & VTD_INV_DESC_WAIT_IF) {
>           /* Interrupt flag */
>           vtd_generate_completion_event(s);
> +    } else if (inv_desc->lo & VTD_INV_DESC_WAIT_FN) {
> +        /*
> +         * SW = 0, IF = 0, FN = 1
> +         * Nothing to do as we process the events sequentially
> +         */

This code looks a bit weird. SW field does not co-exist with IF. But either 
SW or IF can co-exist with FN flag. Is it? Have you already seen a wait 
descriptor that only has FN flag set but no SW nor IF flag?

>       } else {
>           error_report_once("%s: invalid wait desc: hi=%"PRIx64", lo=%"PRIx64
>                             " (unknown type)", __func__, inv_desc->hi,

--
Regards,
Yi Liu