| Message ID | 0f7136ae-0b52-431d-f789-4b7d5bbecb25@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | IOMMU: assorted follow-on to XSA-400 | expand |
On Mon, Apr 11, 2022 at 11:37:28AM +0200, Jan Beulich wrote: > The field taking the value 7 (resulting in 18-bit DIDs when using the > calculation in cap_ndoms(), when the DID fields are only 16 bits wide) > is reserved. Instead of misbehaving in case we would encounter such an > IOMMU, refuse to use it. > > Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> I would maybe prefer to get more specific error message rather than "IOMMU: unsupported" and a dump of the iommu registers. Thanks, Roger.
On 12.04.2022 11:22, Roger Pau Monné wrote: > On Mon, Apr 11, 2022 at 11:37:28AM +0200, Jan Beulich wrote: >> The field taking the value 7 (resulting in 18-bit DIDs when using the >> calculation in cap_ndoms(), when the DID fields are only 16 bits wide) >> is reserved. Instead of misbehaving in case we would encounter such an >> IOMMU, refuse to use it. >> >> Signed-off-by: Jan Beulich <jbeulich@suse.com> > > Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> Thanks. > I would maybe prefer to get more specific error message rather than > "IOMMU: unsupported" and a dump of the iommu registers. Perhaps, but this extends to other properties being checked as well then, I would say, and hence may want to be the subject of yet another patch. Jan
> From: Jan Beulich <jbeulich@suse.com> > Sent: Monday, April 11, 2022 5:37 PM > > The field taking the value 7 (resulting in 18-bit DIDs when using the > calculation in cap_ndoms(), when the DID fields are only 16 bits wide) > is reserved. Instead of misbehaving in case we would encounter such an > IOMMU, refuse to use it. > > Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> > > --- a/xen/drivers/passthrough/vtd/iommu.c > +++ b/xen/drivers/passthrough/vtd/iommu.c > @@ -1267,8 +1267,11 @@ int __init iommu_alloc(struct acpi_drhd_ > > quirk_iommu_caps(iommu); > > + nr_dom = cap_ndoms(iommu->cap); > + > if ( cap_fault_reg_offset(iommu->cap) + > cap_num_fault_regs(iommu->cap) * PRIMARY_FAULT_REG_LEN > > PAGE_SIZE || > + ((nr_dom - 1) >> 16) /* I.e. cap.nd > 6 */ || > (has_register_based_invalidation(iommu) && > ecap_iotlb_offset(iommu->ecap) >= PAGE_SIZE) ) > { > @@ -1294,8 +1297,6 @@ int __init iommu_alloc(struct acpi_drhd_ > if ( !ecap_coherent(iommu->ecap) ) > iommu_non_coherent = true; > > - nr_dom = cap_ndoms(iommu->cap); > - > if ( nr_dom <= DOMID_MASK * 2 + cap_caching_mode(iommu->cap) ) > { > /* Allocate domain id (bit) maps. */
--- a/xen/drivers/passthrough/vtd/iommu.c +++ b/xen/drivers/passthrough/vtd/iommu.c @@ -1267,8 +1267,11 @@ int __init iommu_alloc(struct acpi_drhd_ quirk_iommu_caps(iommu); + nr_dom = cap_ndoms(iommu->cap); + if ( cap_fault_reg_offset(iommu->cap) + cap_num_fault_regs(iommu->cap) * PRIMARY_FAULT_REG_LEN > PAGE_SIZE || + ((nr_dom - 1) >> 16) /* I.e. cap.nd > 6 */ || (has_register_based_invalidation(iommu) && ecap_iotlb_offset(iommu->ecap) >= PAGE_SIZE) ) { @@ -1294,8 +1297,6 @@ int __init iommu_alloc(struct acpi_drhd_ if ( !ecap_coherent(iommu->ecap) ) iommu_non_coherent = true; - nr_dom = cap_ndoms(iommu->cap); - if ( nr_dom <= DOMID_MASK * 2 + cap_caching_mode(iommu->cap) ) { /* Allocate domain id (bit) maps. */
The field taking the value 7 (resulting in 18-bit DIDs when using the calculation in cap_ndoms(), when the DID fields are only 16 bits wide) is reserved. Instead of misbehaving in case we would encounter such an IOMMU, refuse to use it. Signed-off-by: Jan Beulich <jbeulich@suse.com>