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Date: Thu, 2 Jul 2020 09:16:21 +0200 From: Auger Eric <eric.auger@...hat.com> To: Jacob Pan <jacob.jun.pan@...ux.intel.com>, iommu@...ts.linux-foundation.org, LKML <linux-kernel@...r.kernel.org>, Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>, David Woodhouse <dwmw2@...radead.org> Cc: Yi Liu <yi.l.liu@...el.com>, "Tian, Kevin" <kevin.tian@...el.com>, Raj Ashok <ashok.raj@...el.com> Subject: Re: [PATCH v3 3/7] iommu/vt-d: Fix PASID devTLB invalidation Hi Jacob, On 7/1/20 5:33 PM, Jacob Pan wrote: > DevTLB flush can be used for both DMA request with and without PASIDs. > The former uses PASID#0 (RID2PASID), latter uses non-zero PASID for SVA > usage. > > This patch adds a check for PASID value such that devTLB flush with > PASID is used for SVA case. This is more efficient in that multiple > PASIDs can be used by a single device, when tearing down a PASID entry > we shall flush only the devTLB specific to a PASID. > > Fixes: 6f7db75e1c46 ("iommu/vt-d: Add second level page table") > Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com> Reviewed-by: Eric Auger <eric.auger@...hat.com> Thanks Eric > --- > drivers/iommu/intel/pasid.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c > index c81f0f17c6ba..fa0154cce537 100644 > --- a/drivers/iommu/intel/pasid.c > +++ b/drivers/iommu/intel/pasid.c > @@ -486,7 +486,16 @@ devtlb_invalidation_with_pasid(struct intel_iommu *iommu, > qdep = info->ats_qdep; > pfsid = info->pfsid; > > - qi_flush_dev_iotlb(iommu, sid, pfsid, qdep, 0, 64 - VTD_PAGE_SHIFT); > + /* > + * When PASID 0 is used, it indicates RID2PASID(DMA request w/o PASID), > + * devTLB flush w/o PASID should be used. For non-zero PASID under > + * SVA usage, device could do DMA with multiple PASIDs. It is more > + * efficient to flush devTLB specific to the PASID. > + */ > + if (pasid == PASID_RID2PASID) > + qi_flush_dev_iotlb(iommu, sid, pfsid, qdep, 0, 64 - VTD_PAGE_SHIFT); > + else > + qi_flush_dev_iotlb_pasid(iommu, sid, pfsid, pasid, qdep, 0, 64 - VTD_PAGE_SHIFT); > } > > void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct device *dev, >
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