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From: Nicolin Chen <nicolinc@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>, "Tian, Kevin" <kevin.tian@intel.com>
Cc: "corbet@lwn.net" <corbet@lwn.net>,
	"will@kernel.org" <will@kernel.org>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"suravee.suthikulpanit@amd.com" <suravee.suthikulpanit@amd.com>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"dwmw2@infradead.org" <dwmw2@infradead.org>,
	"baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
	"shuah@kernel.org" <shuah@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kselftest@vger.kernel.org"
	<linux-kselftest@vger.kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"jean-philippe@linaro.org" <jean-philippe@linaro.org>,
	"mdf@kernel.org" <mdf@kernel.org>,
	"mshavit@google.com" <mshavit@google.com>,
	"shameerali.kolothum.thodi@huawei.com"
	<shameerali.kolothum.thodi@huawei.com>,
	"smostafa@google.com" <smostafa@google.com>,
	"ddutile@redhat.com" <ddutile@redhat.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>,
	"patches@lists.linux.dev" <patches@lists.linux.dev>
Subject: Re: [PATCH v6 07/14] iommufd/viommu: Add iommufd_viommu_report_event helper
Date: Thu, 20 Feb 2025 13:16:26 -0800	[thread overview]
Message-ID: <Z7ebqtJUwzgOIeSC@Asurada-Nvidia> (raw)
In-Reply-To: <BN9PR11MB52766CE9C579D3EE1CE1A7058CC52@BN9PR11MB5276.namprd11.prod.outlook.com>

On Wed, Feb 19, 2025 at 06:58:16AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Tuesday, February 18, 2025 11:36 PM
> > 
> > On Fri, Jan 24, 2025 at 04:30:36PM -0800, Nicolin Chen wrote:
> > > +int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
> > > +				enum iommu_veventq_type type, void
> > *event_data,
> > > +				size_t data_len)
> > > +{
> > > +	struct iommufd_veventq *veventq;
> > > +	struct iommufd_vevent *vevent;
> > > +	int rc = 0;
> > > +
> > > +	if (WARN_ON_ONCE(!data_len || !event_data))
> > > +		return -EINVAL;
> > > +
> > > +	down_read(&viommu->veventqs_rwsem);
> > > +
> > > +	veventq = iommufd_viommu_find_veventq(viommu, type);
> > > +	if (!veventq) {
> > > +		rc = -EOPNOTSUPP;
> > > +		goto out_unlock_veventqs;
> > > +	}
> > > +
> > > +	if (atomic_read(&veventq->num_events) == veventq->depth) {
> > > +		vevent = &veventq->overflow;
> > > +		goto out_set_header;
> > > +	}
> > > +
> > > +	vevent = kmalloc(struct_size(vevent, event_data, data_len),
> > GFP_KERNEL);
> > > +	if (!vevent) {
> > > +		rc = -ENOMEM;
> > > +		goto out_unlock_veventqs;
> > 
> > This should record an overflow too
> > 
> 
> In that case probably we want to rename 'overflow' to 'lost_event'
> which counts lost events for whatever reasons (overflow, oom, etc.)

Naming-wise, I think it may sound better to call the overflow node
just an 'exception' that concludes with lost eventsfor different
reasons.

A complication is that this 'exception' would give userspace a very
implicit reason as the node just report the number of lost events
v.s. providing the reason to each lost event.

With this, maybe the IOMMU_VEVENTQ_FLAG_OVERFLOW in the uAPI should
be just IOMMU_VEVENTQ_FLAG_EXCEPTION? Any better idea?

Thanks
Nicolin

  reply	other threads:[~2025-02-20 21:16 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-25  0:30 [PATCH v6 00/14] iommufd: Add vIOMMU infrastructure (Part-3: vEVENTQ) Nicolin Chen
2025-01-25  0:30 ` [PATCH v6 01/14] iommufd/fault: Move two fault functions out of the header Nicolin Chen
2025-02-14 20:15   ` Jason Gunthorpe
2025-02-18  5:05   ` Tian, Kevin
2025-01-25  0:30 ` [PATCH v6 02/14] iommufd/fault: Add an iommufd_fault_init() helper Nicolin Chen
2025-01-25  0:30 ` [PATCH v6 03/14] iommufd: Abstract an iommufd_eventq from iommufd_fault Nicolin Chen
2025-02-14 20:23   ` Jason Gunthorpe
2025-01-25  0:30 ` [PATCH v6 04/14] iommufd: Rename fault.c to eventq.c Nicolin Chen
2025-01-25  0:30 ` [PATCH v6 05/14] iommufd: Add IOMMUFD_OBJ_VEVENTQ and IOMMUFD_CMD_VEVENTQ_ALLOC Nicolin Chen
2025-02-18  5:13   ` Tian, Kevin
2025-02-18 17:53     ` Nicolin Chen
2025-02-18 15:29   ` Jason Gunthorpe
2025-02-18 17:47     ` Nicolin Chen
2025-02-18 18:08       ` Jason Gunthorpe
2025-02-18 18:15         ` Nicolin Chen
2025-01-25  0:30 ` [PATCH v6 06/14] iommufd/viommu: Add iommufd_viommu_get_vdev_id helper Nicolin Chen
2025-02-18 15:31   ` Jason Gunthorpe
2025-02-20  5:17     ` Nicolin Chen
2025-02-20 16:19       ` Jason Gunthorpe
2025-01-25  0:30 ` [PATCH v6 07/14] iommufd/viommu: Add iommufd_viommu_report_event helper Nicolin Chen
2025-02-18  5:14   ` Tian, Kevin
2025-02-18 15:35   ` Jason Gunthorpe
2025-02-19  6:58     ` Tian, Kevin
2025-02-20 21:16       ` Nicolin Chen [this message]
2025-02-21  4:27         ` Tian, Kevin
2025-02-21 13:39           ` Jason Gunthorpe
2025-01-25  0:30 ` [PATCH v6 08/14] iommufd/selftest: Require vdev_id when attaching to a nested domain Nicolin Chen
2025-02-18  5:15   ` Tian, Kevin
2025-01-25  0:30 ` [PATCH v6 09/14] iommufd/selftest: Add IOMMU_TEST_OP_TRIGGER_VEVENT for vEVENTQ coverage Nicolin Chen
2025-02-18  5:16   ` Tian, Kevin
2025-01-25  0:30 ` [PATCH v6 10/14] iommufd/selftest: Add IOMMU_VEVENTQ_ALLOC test coverage Nicolin Chen
2025-02-18  5:19   ` Tian, Kevin
2025-01-25  0:30 ` [PATCH v6 11/14] Documentation: userspace-api: iommufd: Update FAULT and VEVENTQ Nicolin Chen
2025-01-28  8:21   ` Bagas Sanjaya
2025-02-18 17:02   ` Jason Gunthorpe
2025-01-25  0:30 ` [PATCH v6 12/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster Nicolin Chen
2025-02-18 17:08   ` Jason Gunthorpe
2025-02-20  7:16     ` Nicolin Chen
2025-01-25  0:30 ` [PATCH v6 13/14] iommu/arm-smmu-v3: Report events that belong to devices attached to vIOMMU Nicolin Chen
2025-02-18  5:21   ` Tian, Kevin
2025-02-18 17:18   ` Jason Gunthorpe
2025-02-18 18:28     ` Nicolin Chen
2025-02-18 18:50       ` Jason Gunthorpe
2025-02-18 19:02         ` Nicolin Chen
2025-02-18 19:08           ` Jason Gunthorpe
2025-02-18 19:27             ` Nicolin Chen
2025-02-20 20:45         ` Nicolin Chen
2025-02-20 23:24           ` Jason Gunthorpe
2025-02-21  8:10             ` Nicolin Chen
2025-01-25  0:30 ` [PATCH v6 14/14] iommu/arm-smmu-v3: Set MEV bit in nested STE for DoS mitigations Nicolin Chen
2025-02-18  5:24   ` Tian, Kevin
2025-02-18 18:17     ` Pranjal Shrivastava
2025-02-18 18:52       ` Jason Gunthorpe
2025-02-20  7:12         ` Nicolin Chen
2025-02-18 18:53       ` Nicolin Chen
2025-02-20 16:15         ` Pranjal Shrivastava
2025-02-18 17:21   ` Jason Gunthorpe
2025-02-18 18:14     ` Nicolin Chen
2025-02-20  9:09   ` Nicolin Chen
2025-02-14  8:03 ` [PATCH v6 00/14] iommufd: Add vIOMMU infrastructure (Part-3: vEVENTQ) Nicolin Chen

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