On Mon, Jun 07, 2021 at 11:25:39AM -0700, Nadav Amit wrote:
> From: Nadav Amit <[email protected]>
>
> 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 <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Jiajun Cao <[email protected]>
> Cc: Robin Murphy <[email protected]>
> Cc: Lu Baolu <[email protected]>
> Cc: [email protected]
> Cc: [email protected]>
> Signed-off-by: Nadav Amit <[email protected]>
> ---
> include/linux/iommu.h | 41 +++++++++++++++++++++++++++++++++--------
> 1 file changed, 33 insertions(+), 8 deletions(-)
[...]
> 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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