From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>,
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Subject: Re: [PATCH v4 6/7] iommu: Introduce iommu_dev_reset_prepare() and iommu_dev_reset_done()
Date: Mon, 15 Sep 2025 09:53:57 -0300 [thread overview]
Message-ID: <20250915125357.GH1024672@nvidia.com> (raw)
In-Reply-To: <BL1PR11MB5271BE949150D4C2B5EC589A8C08A@BL1PR11MB5271.namprd11.prod.outlook.com>
On Fri, Sep 12, 2025 at 09:49:13AM +0000, Tian, Kevin wrote:
> > There are two corner cases that won't work:
> > 1. Alias devices that share the same RID
> > Blocking one device also blocks the other alias devices that might not
> > want a reset. Given that it's very rare for an alias device to support
> > ATS, simply skip the blocking routine.
>
> it also applies to the devices in the same iommu group. While one device
> is being reset, all other devices in the group cannot change the domain.
> This needs to be documented in the attach uAPI.
I think we should just exclude multi-device groups for the first
version of this.
We really need to fixup multi-device groups to distinguish between
cases where the group is there for aliases and we must have consistent
domains across the whole group and cases where the group is there just
for representing isolation and different domains are fine.
We are now having workloads where this difference matters, ATS reset
is one case, but I'm interesting in seeing iommufd able to control
domains per-device within a group. We have some HW that wants this.
Jason
next prev parent reply other threads:[~2025-09-15 12:54 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-31 23:31 [PATCH v4 0/7] Disable ATS via iommu during PCI resets Nicolin Chen
2025-08-31 23:31 ` [PATCH v4 1/7] iommu/arm-smmu-v3: Add release_domain to attach prior to release_dev() Nicolin Chen
2025-09-12 9:33 ` Tian, Kevin
2025-09-15 12:35 ` Jason Gunthorpe
2025-09-19 22:47 ` Nicolin Chen
2025-09-23 17:22 ` Jason Gunthorpe
2025-09-23 17:37 ` Nicolin Chen
2025-09-23 17:44 ` Jason Gunthorpe
2025-09-23 19:46 ` Nicolin Chen
2025-08-31 23:31 ` [PATCH v4 2/7] iommu: Lock group->mutex in iommu_deferred_attach() Nicolin Chen
2025-09-12 9:34 ` Tian, Kevin
2025-08-31 23:31 ` [PATCH v4 3/7] iommu: Pass in gdev to __iommu_device_set_domain Nicolin Chen
2025-08-31 23:31 ` [PATCH v4 4/7] iommu: Pass in old domain to attach_dev callback functions Nicolin Chen
2025-09-12 9:35 ` Tian, Kevin
2025-09-19 22:56 ` Nicolin Chen
2025-09-24 18:43 ` Jason Gunthorpe
2025-09-24 19:18 ` Nicolin Chen
2025-09-24 19:22 ` Jason Gunthorpe
2025-08-31 23:31 ` [PATCH v4 5/7] iommu: Add iommu_get_domain_for_dev_locked() helper Nicolin Chen
2025-09-12 9:36 ` Tian, Kevin
2025-09-19 23:14 ` Nicolin Chen
2025-09-24 19:10 ` Jason Gunthorpe
2025-09-24 19:49 ` Nicolin Chen
2025-09-24 19:52 ` Jason Gunthorpe
2025-09-24 20:02 ` Nicolin Chen
2025-09-24 21:02 ` Jason Gunthorpe
2025-08-31 23:31 ` [PATCH v4 6/7] iommu: Introduce iommu_dev_reset_prepare() and iommu_dev_reset_done() Nicolin Chen
2025-09-12 9:49 ` Tian, Kevin
2025-09-15 12:53 ` Jason Gunthorpe [this message]
2025-09-22 19:39 ` Nicolin Chen
2025-08-31 23:31 ` [PATCH v4 7/7] pci: Suspend iommu function prior to resetting a device Nicolin Chen
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