Re: [PATCH v8 06/10] iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers

[Suthikulpanit, Suravee]

On 11/1/2024 7:10 PM, Jason Gunthorpe wrote:
> On Thu, Oct 31, 2024 at 06:42:39PM +0000, Suravee Suthikulpanit wrote:
> > +struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 segid, u16 devid)
> > +{
> > +	struct ivhd_dte_flags *e;
> > +	unsigned int best_len = UINT_MAX;
> > +	struct dev_table_entry *dte = NULL;
> > +
> > +	for_each_ivhd_dte_flags(e) {
> > +		/*
> > +		 * Need to go through the whole list to find the smallest range,
> > +		 * which contains the devid.
> > +		 */
> > +		if ((e->segid == segid) &&
> > +		    (e->devid_first >= devid) &&
> > +		    (e->devid_last <= devid)) {
>
> Again, I don't know much about this format, but are you sure about
> this logic? Consider:
>
>   e->devid_first = 10
>   devid = 12
>   e->devid_last = 15
>
>   (e->devid_first >= devid) == 10 >= 12 == FALSE
>   (e->devid_last <= devid) == 15 <= 12 == FALSE
>
> FALSE && FALSE == FALSE
>
> It seems to me it does not do what the comment says? Compare to the
> version I sent in my last email

Ah, sorry again for this stupid mistake. You are correct. Thank you very 
much for catching this. I am sending V9 with only the fix for this.

Thanks,
Suravee