From: Will Deacon <will@kernel.org> To: Nadav Amit <nadav.amit@gmail.com> Cc: Joerg Roedel <joro@8bytes.org>, Nadav Amit <namit@vmware.com>, Jiajun Cao <caojiajun@vmware.com>, Robin Murphy <robin.murphy@arm.com>, Lu Baolu <baolu.lu@linux.intel.com>, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/6] iommu: Factor iommu_iotlb_gather_is_disjoint() out Date: Fri, 11 Jun 2021 14:57:47 +0100 [thread overview] Message-ID: <20210611135746.GC15776@willie-the-truck> (raw) In-Reply-To: <20210607182541.119756-5-namit@vmware.com> 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(-) [...] > 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
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org> To: Nadav Amit <nadav.amit@gmail.com> Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Nadav Amit <namit@vmware.com>, Jiajun Cao <caojiajun@vmware.com>, Robin Murphy <robin.murphy@arm.com> Subject: Re: [PATCH v3 4/6] iommu: Factor iommu_iotlb_gather_is_disjoint() out Date: Fri, 11 Jun 2021 14:57:47 +0100 [thread overview] Message-ID: <20210611135746.GC15776@willie-the-truck> (raw) In-Reply-To: <20210607182541.119756-5-namit@vmware.com> 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(-) [...] > 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 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-06-11 13:57 UTC|newest] Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-07 18:25 [PATCH v3 0/6] iommu/amd: Enable page-selective flushes Nadav Amit 2021-06-07 18:25 ` Nadav Amit 2021-06-07 18:25 ` [PATCH v3 1/6] iommu/amd: Selective flush on unmap Nadav Amit 2021-06-07 18:25 ` Nadav Amit 2021-06-07 18:25 ` [PATCH v3 2/6] iommu/amd: Do not use flush-queue when NpCache is on Nadav Amit 2021-06-07 18:25 ` Nadav Amit 2021-06-15 13:08 ` Robin Murphy 2021-06-15 13:08 ` Robin Murphy 2021-06-15 18:26 ` Nadav Amit 2021-06-15 18:26 ` Nadav Amit 2021-06-15 19:36 ` Robin Murphy 2021-06-15 19:36 ` Robin Murphy 2021-06-07 18:25 ` [PATCH v3 3/6] iommu: Improve iommu_iotlb_gather helpers Nadav Amit 2021-06-07 18:25 ` Nadav Amit 2021-06-11 13:50 ` Will Deacon 2021-06-11 13:50 ` Will Deacon 2021-06-15 10:42 ` Robin Murphy 2021-06-15 10:42 ` Robin Murphy 2021-06-15 19:05 ` Nadav Amit 2021-06-15 19:05 ` Nadav Amit 2021-06-15 19:07 ` Nadav Amit 2021-06-15 19:07 ` Nadav Amit 2021-06-15 12:29 ` Yong Wu 2021-06-15 12:29 ` Yong Wu 2021-06-15 12:41 ` Robin Murphy 2021-06-15 12:41 ` Robin Murphy 2021-06-07 18:25 ` [PATCH v3 4/6] iommu: Factor iommu_iotlb_gather_is_disjoint() out Nadav Amit 2021-06-07 18:25 ` Nadav Amit 2021-06-11 13:57 ` Will Deacon [this message] 2021-06-11 13:57 ` Will Deacon 2021-06-11 16:50 ` Nadav Amit 2021-06-11 16:50 ` Nadav Amit 2021-06-15 10:29 ` Will Deacon 2021-06-15 10:29 ` Will Deacon 2021-06-15 18:54 ` Nadav Amit 2021-06-15 18:54 ` Nadav Amit 2021-06-07 18:25 ` [PATCH v3 5/6] iommu/amd: Tailored gather logic for AMD Nadav Amit 2021-06-07 18:25 ` Nadav Amit 2021-06-15 12:55 ` Robin Murphy 2021-06-15 12:55 ` Robin Murphy 2021-06-15 18:14 ` Nadav Amit 2021-06-15 18:14 ` Nadav Amit 2021-06-15 19:20 ` Robin Murphy 2021-06-15 19:20 ` Robin Murphy 2021-06-15 19:46 ` Nadav Amit 2021-06-15 19:46 ` Nadav Amit 2021-06-07 18:25 ` [PATCH v3 6/6] iommu/amd: Sync once for scatter-gather operations Nadav Amit 2021-06-07 18:25 ` Nadav Amit 2021-06-15 11:25 ` Robin Murphy 2021-06-15 11:25 ` Robin Murphy 2021-06-15 18:51 ` Nadav Amit 2021-06-15 18:51 ` Nadav Amit
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