Re: [PATCH v4 12/12] iommu/vt-d: Disallow nesting on domains with read-only mappings

[Baolu Lu]

On 2023/8/2 15:59, Tian, Kevin wrote:
> > From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> > Sent: Monday, July 24, 2023 7:14 PM
> >
> > @@ -2147,6 +2148,18 @@ __domain_mapping(struct dmar_domain
> > *domain, unsigned long iov_pfn,
> >   	if ((prot & (DMA_PTE_READ|DMA_PTE_WRITE)) == 0)
> >   		return -EINVAL;
> >
> > +	if (!(prot & DMA_PTE_WRITE) && !domain->read_only_mapped) {
> > +		spin_lock_irqsave(&domain->lock, flags);
> > +		if (domain->set_nested) {
> > +			pr_err_ratelimited("No read-only mapping
> > permitted\n");
>
> "Read-only mapping is disallowed on the domain which serves as the
> parent in a nested configuration, due to HW errata (ERRATA_772415_SPR17)"

Ack.

> > +	u8 read_only_mapped:1;		/* domain has mappings with
> > read-only
> > +					 * permission.
> > +					 */
> > +	u8 set_nested:1;		/* has other domains nested on it */
>
> what about "is_parent"?

"is_parent" is still a bit generic. How about "is_nested_parent"?

> > +	spin_lock_irqsave(&s2_dmar_domain->lock, flags);
> > +	if (s2_dmar_domain->read_only_mapped) {
> > +		spin_unlock_irqrestore(&s2_dmar_domain->lock, flags);
> > +		pr_err_ratelimited("S2 domain has read-only mappings\n");
>
> "Nested configuration is disallowed when the stage-2 domain already
> has read-only mappings, due to HW errata (ERRATA_772415_SPR17)"

Ack.

Best regards,
baolu