| Message ID | d42df6c9d7d854a6b5c4586b02000678e71916fc.1501163100.git.robin.murphy@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Robin, On 27/07/2017 16:54, Robin Murphy wrote: > If the IOMMU driver advertises 'real' reserved regions for MSIs, but > still includes the software-managed region as well, we are currently > blind to the former and will configure the IOMMU domain to map MSIs into > the latter, which is unlikely to work as expected. > > Since it would take a ridiculous hardware topology for both regions to > be valid (which would be rather difficult to support in general), we > should be safe to assume that the presence of any hardware regions makes > the software region irrelevant. However, the IOMMU driver might still > advertise the software region by default, particularly if the hardware > regions are filled in elsewhere by generic code, so it might not be fair > for VFIO to be super-strict about not mixing them. To that end, make > vfio_iommu_has_sw_msi() robust against the presence of both region types > at once, so that we end up doing what is almost certainly right, rather > than what is almost certainly wrong. > > Signed-off-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Thanks Eric > --- > drivers/vfio/vfio_iommu_type1.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 2328be628f21..92155cce926d 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -1169,13 +1169,21 @@ static bool vfio_iommu_has_sw_msi(struct iommu_group *group, phys_addr_t *base) > INIT_LIST_HEAD(&group_resv_regions); > iommu_get_group_resv_regions(group, &group_resv_regions); > list_for_each_entry(region, &group_resv_regions, list) { > + /* > + * The presence of any 'real' MSI regions should take > + * precedence over the software-managed one if the > + * IOMMU driver happens to advertise both types. > + */ > + if (region->type == IOMMU_RESV_MSI) { > + ret = false; > + break; > + } > + > if (region->type == IOMMU_RESV_SW_MSI) { > *base = region->start; > ret = true; > - goto out; > } > } > -out: > list_for_each_entry_safe(region, next, &group_resv_regions, list) > kfree(region); > return ret; >
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 2328be628f21..92155cce926d 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -1169,13 +1169,21 @@ static bool vfio_iommu_has_sw_msi(struct iommu_group *group, phys_addr_t *base) INIT_LIST_HEAD(&group_resv_regions); iommu_get_group_resv_regions(group, &group_resv_regions); list_for_each_entry(region, &group_resv_regions, list) { + /* + * The presence of any 'real' MSI regions should take + * precedence over the software-managed one if the + * IOMMU driver happens to advertise both types. + */ + if (region->type == IOMMU_RESV_MSI) { + ret = false; + break; + } + if (region->type == IOMMU_RESV_SW_MSI) { *base = region->start; ret = true; - goto out; } } -out: list_for_each_entry_safe(region, next, &group_resv_regions, list) kfree(region); return ret;
If the IOMMU driver advertises 'real' reserved regions for MSIs, but still includes the software-managed region as well, we are currently blind to the former and will configure the IOMMU domain to map MSIs into the latter, which is unlikely to work as expected. Since it would take a ridiculous hardware topology for both regions to be valid (which would be rather difficult to support in general), we should be safe to assume that the presence of any hardware regions makes the software region irrelevant. However, the IOMMU driver might still advertise the software region by default, particularly if the hardware regions are filled in elsewhere by generic code, so it might not be fair for VFIO to be super-strict about not mixing them. To that end, make vfio_iommu_has_sw_msi() robust against the presence of both region types at once, so that we end up doing what is almost certainly right, rather than what is almost certainly wrong. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/vfio/vfio_iommu_type1.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)