Messages in this thread | | | Date | Fri, 11 Jun 2021 14:57:47 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v3 4/6] iommu: Factor iommu_iotlb_gather_is_disjoint() out |
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On Mon, Jun 07, 2021 at 11:25:39AM -0700, Nadav Amit wrote: > From: Nadav Amit <namit@vmware.com> > > Refactor iommu_iotlb_gather_add_page() and factor out the logic that > detects whether IOTLB gather range and a new range are disjoint. To be > used by the next patch that implements different gathering logic for > AMD. > > Cc: Joerg Roedel <joro@8bytes.org> > Cc: Will Deacon <will@kernel.org> > Cc: Jiajun Cao <caojiajun@vmware.com> > Cc: Robin Murphy <robin.murphy@arm.com> > Cc: Lu Baolu <baolu.lu@linux.intel.com> > Cc: iommu@lists.linux-foundation.org > Cc: linux-kernel@vger.kernel.org> > Signed-off-by: Nadav Amit <namit@vmware.com> > --- > include/linux/iommu.h | 41 +++++++++++++++++++++++++++++++++-------- > 1 file changed, 33 insertions(+), 8 deletions(-)
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> diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index f254c62f3720..b5a2bfc68fb0 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -497,6 +497,28 @@ static inline void iommu_iotlb_sync(struct iommu_domain *domain, > iommu_iotlb_gather_init(iotlb_gather); > } > > +/** > + * iommu_iotlb_gather_is_disjoint - Checks whether a new range is disjoint > + * > + * @gather: TLB gather data > + * @iova: start of page to invalidate > + * @size: size of page to invalidate > + * > + * Helper for IOMMU drivers to check whether a new range is and the gathered > + * range are disjoint.
I can't quite parse this. Delete the "is"?
> For many IOMMUs, flushing the IOMMU in this case is > + * better than merging the two, which might lead to unnecessary invalidations. > + */ > +static inline > +bool iommu_iotlb_gather_is_disjoint(struct iommu_iotlb_gather *gather, > + unsigned long iova, size_t size) > +{ > + unsigned long start = iova, end = start + size - 1; > + > + return gather->end != 0 && > + (end + 1 < gather->start || start > gather->end + 1); > +} > + > + > /** > * iommu_iotlb_gather_add_range - Gather for address-based TLB invalidation > * @gather: TLB gather data > @@ -533,20 +555,16 @@ static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain, > struct iommu_iotlb_gather *gather, > unsigned long iova, size_t size) > { > - unsigned long start = iova, end = start + size - 1; > - > /* > * If the new page is disjoint from the current range or is mapped at > * a different granularity, then sync the TLB so that the gather > * structure can be rewritten. > */ > - if (gather->pgsize != size || > - end + 1 < gather->start || start > gather->end + 1) { > - if (gather->pgsize) > - iommu_iotlb_sync(domain, gather); > - gather->pgsize = size; > - } > + if ((gather->pgsize && gather->pgsize != size) || > + iommu_iotlb_gather_is_disjoint(gather, iova, size)) > + iommu_iotlb_sync(domain, gather); > > + gather->pgsize = size;
Why have you made this unconditional? I think it's ok, but just not sure if it's necessary or not.
Will
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