From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: will@kernel.org, robin.murphy@arm.com,
Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>,
joro@8bytes.org, bhelgaas@google.com, praan@google.com,
kevin.tian@intel.com, kees@kernel.org, smostafa@google.com,
baolu.lu@linux.intel.com, Jean-Philippe Brucker <jpb@kernel.org>,
Eric Auger <eric.auger@redhat.com>,
linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
skaestle@nvidia.com, mmarrid@nvidia.com, skolothumtho@nvidia.com,
bbiber@nvidia.com, harsha.v@oss.qualcomm.com
Subject: Re: [PATCH v5 04/15] iommu/arm-smmu-v3: Drain in-flight fault events on domain detach
Date: Thu, 24 Sep 2026 11:03:50 -0300 [thread overview]
Message-ID: <20260924140350.GA9354@nvidia.com> (raw)
In-Reply-To: <arSAEjFLr5y/ycJx@nvidia.com>
On Wed, Sep 23, 2026 at 06:42:42PM -0700, Nicolin Chen wrote:
> There is a problem, however, if one of them wraps twice (i.e. 2 x
> queue size): then it would miss the exit at the target length even
> if it is already much longer; and the penalty would be a timeout,
> yet at that moment the queue is definitely drained.
Yes, we this routine should not hit timeouts, that's really bad. The
point is you can hit a false timeout because the algorithm does not
work.
> > > FWIW, the idea of HW drain came from intel_iommu_drain_pasid_prq()..
> >
> > Yeah, but I think they might have over done it too..
>
> I see.
The HW queue may need flushing on the device hot remove path, that
depends how they implemented things. Like on ARM you had a mutex
around the whole thing dev pointer so we don't even need that..
Jason
next prev parent reply other threads:[~2026-09-24 14:04 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-15 16:38 [PATCH v5 00/15] iommu/arm-smmu-v3: Add PRI support Nicolin Chen
2026-09-15 16:38 ` [PATCH v5 01/15] iommu/arm-smmu-v3: Disable the impl before disabling the SMMU on shutdown Nicolin Chen
2026-09-15 16:51 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 02/15] iommu/arm-smmu-v3: Add arm_smmu_attach_release() Nicolin Chen
2026-09-15 16:48 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 03/15] iommu/arm-smmu-v3: Add Q_POS() macro Nicolin Chen
2026-09-15 16:42 ` sashiko-bot
2026-09-15 23:19 ` Jonathan Cameron
2026-09-15 16:38 ` [PATCH v5 04/15] iommu/arm-smmu-v3: Drain in-flight fault events on domain detach Nicolin Chen
2026-09-15 16:51 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-23 22:33 ` Nicolin Chen
2026-09-23 23:39 ` Jason Gunthorpe
2026-09-24 1:42 ` Nicolin Chen
2026-09-24 14:03 ` Jason Gunthorpe [this message]
2026-09-28 22:29 ` Nicolin Chen
2026-09-29 19:46 ` Nicolin Chen
2026-09-15 16:38 ` [PATCH v5 05/15] iommu/arm-smmu-v3: Flush in-flight fault work " Nicolin Chen
2026-09-15 16:57 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 06/15] iommu/arm-smmu-v3: Allocate IOPF queue without FEAT_SVA Nicolin Chen
2026-09-15 16:47 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 07/15] iommu/arm-smmu-v3: Submit CMDQ_OP_PRI_RESP for IOPF event Nicolin Chen
2026-09-15 17:02 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 08/15] iommu/arm-smmu-v3: Disable the queue IRQs before disabling the SMMU Nicolin Chen
2026-09-15 16:48 ` sashiko-bot
2026-09-15 23:21 ` Jonathan Cameron
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-24 1:12 ` Nicolin Chen
2026-09-15 16:38 ` [PATCH v5 09/15] iommu/arm-smmu-v3: Disable PRI when no IRQ handler is registered Nicolin Chen
2026-09-15 16:53 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 10/15] iommu/arm-smmu-v3: Support PRI Page Request in arm_smmu_handle_ppr() Nicolin Chen
2026-09-15 16:52 ` sashiko-bot
2026-09-15 23:22 ` Jonathan Cameron
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 11/15] iommu/arm-smmu-v3: Discard partial PRI faults on PRIQ overflow Nicolin Chen
2026-09-15 16:57 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 12/15] iommu/arm-smmu-v3: Allocate IOPF queue for ARM_SMMU_FEAT_PRI Nicolin Chen
2026-09-15 16:56 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 13/15] PCI/ATS: Add PRI stubs Nicolin Chen
2026-09-15 16:51 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 14/15] PCI/ATS: Export pci_enable_pri() and pci_reset_pri() Nicolin Chen
2026-09-15 16:49 ` sashiko-bot
2026-09-23 18:37 ` Jason Gunthorpe
2026-09-15 16:38 ` [PATCH v5 15/15] iommu/arm-smmu-v3: Enable PRI for PCI device in arm_smmu_probe_device() Nicolin Chen
2026-09-15 16:59 ` sashiko-bot
2026-10-04 16:50 ` [PATCH v5 00/15] iommu/arm-smmu-v3: Add PRI support Will Deacon
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