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From: "Tian, Kevin" <kevin.tian@intel.com>
To: "Liu, Yi L" <yi.l.liu@intel.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"jgg@nvidia.com" <jgg@nvidia.com>
Cc: "joro@8bytes.org" <joro@8bytes.org>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"nicolinc@nvidia.com" <nicolinc@nvidia.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"chao.p.peng@linux.intel.com" <chao.p.peng@linux.intel.com>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
	"baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
	"Duan, Zhenzhong" <zhenzhong.duan@intel.com>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>
Subject: RE: [PATCH v2 0/4] vfio-pci support pasid attach/detach
Date: Tue, 16 Apr 2024 08:38:50 +0000	[thread overview]
Message-ID: <BN9PR11MB5276318EF2CD66BEF826F59A8C082@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20240412082121.33382-1-yi.l.liu@intel.com>

> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Friday, April 12, 2024 4:21 PM
> 
> A userspace VMM is supposed to get the details of the device's PASID
> capability
> and assemble a virtual PASID capability in a proper offset in the virtual PCI
> configuration space. While it is still an open on how to get the available
> offsets. Devices may have hidden bits that are not in the PCI cap chain. For
> now, there are two options to get the available offsets.[2]
> 
> - Report the available offsets via ioctl. This requires device-specific logic
>   to provide available offsets. e.g., vfio-pci variant driver. Or may the device
>   provide the available offset by DVSEC.
> - Store the available offsets in a static table in userspace VMM. VMM gets the
>   empty offsets from this table.
> 

I'm not a fan of requesting a variant driver for every PASID-capable
VF just for the purpose of reporting a free range in the PCI config space.

It's easier to do that quirk in userspace.

But I like Alex's original comment that at least for PF there is no reason
to hide the offset. there could be a flag+field to communicate it. or 
if there will be a new variant VF driver for other purposes e.g. migration
it can certainly fill the field too.

  parent reply	other threads:[~2024-04-16  8:38 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-12  8:21 [PATCH v2 0/4] vfio-pci support pasid attach/detach Yi Liu
2024-04-12  8:21 ` [PATCH v2 1/4] ida: Add ida_get_lowest() Yi Liu
2024-04-16 16:03   ` Alex Williamson
2024-04-18  7:02     ` Yi Liu
2024-04-18 16:23       ` Alex Williamson
2024-04-18 17:12         ` Jason Gunthorpe
2024-04-19 13:43           ` Yi Liu
2024-04-19 13:55             ` Alex Williamson
2024-04-19 14:00               ` Jason Gunthorpe
2024-04-23  7:19                 ` Yi Liu
2024-04-19 13:40         ` Yi Liu
2024-04-12  8:21 ` [PATCH v2 2/4] vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices Yi Liu
2024-04-16  9:01   ` Tian, Kevin
2024-04-16  9:24     ` Yi Liu
2024-04-16  9:47       ` Tian, Kevin
2024-04-18  7:04         ` Yi Liu
2024-04-23 12:43   ` Jason Gunthorpe
2024-04-24  0:33     ` Tian, Kevin
2024-04-24  4:48     ` Yi Liu
2024-04-12  8:21 ` [PATCH v2 3/4] vfio: Add VFIO_DEVICE_PASID_[AT|DE]TACH_IOMMUFD_PT Yi Liu
2024-04-16  9:13   ` Tian, Kevin
2024-04-16  9:36     ` Yi Liu
2024-04-23 12:45   ` Jason Gunthorpe
2024-04-12  8:21 ` [PATCH v2 4/4] vfio: Report PASID capability via VFIO_DEVICE_FEATURE ioctl Yi Liu
2024-04-16  9:40   ` Tian, Kevin
2024-04-16 17:57   ` Alex Williamson
2024-04-17  7:09     ` Tian, Kevin
2024-04-17 20:25       ` Alex Williamson
2024-04-18  0:21         ` Tian, Kevin
2024-04-18  8:23           ` Yi Liu
2024-04-18 16:34           ` Alex Williamson
2024-04-23 12:39   ` Jason Gunthorpe
2024-04-24  0:24     ` Tian, Kevin
2024-04-24 13:59       ` Jason Gunthorpe
2024-04-16  8:38 ` Tian, Kevin [this message]
2024-04-16 17:50   ` [PATCH v2 0/4] vfio-pci support pasid attach/detach Jason Gunthorpe
2024-04-17  7:16     ` Tian, Kevin
2024-04-17 12:20       ` Jason Gunthorpe
2024-04-17 23:02         ` Alex Williamson
2024-04-18  0:06           ` Tian, Kevin
2024-04-18  9:03             ` Yi Liu
2024-04-18 20:37               ` Alex Williamson
2024-04-19  5:52                 ` Tian, Kevin
2024-04-19 16:35                   ` Alex Williamson
2024-04-23  7:43                     ` Tian, Kevin
2024-04-23 12:01                       ` Jason Gunthorpe
2024-04-23 23:47                         ` Tian, Kevin
2024-04-24  0:12                           ` Jason Gunthorpe
2024-04-24  2:57                             ` Tian, Kevin
2024-04-24 12:29                               ` Baolu Lu
2024-04-24 14:04                               ` Jason Gunthorpe
2024-04-24  5:19                             ` Tian, Kevin
2024-04-24 14:15                               ` Jason Gunthorpe
2024-04-24 18:38                                 ` Alex Williamson
2024-04-24 18:45                                   ` Jason Gunthorpe
2024-04-24 18:24                             ` Alex Williamson
2024-04-24 18:36                               ` Jason Gunthorpe
2024-04-24 20:13                                 ` Alex Williamson
2024-04-26 14:11                                   ` Jason Gunthorpe
2024-04-26 20:13                                     ` Alex Williamson
2024-04-28  6:19                                       ` Tian, Kevin
2024-04-29  7:43                                         ` Yi Liu
2024-04-29 17:15                                         ` Jason Gunthorpe
2024-04-29 17:44                                       ` Jason Gunthorpe
2024-04-27  5:05                                     ` Christoph Hellwig
2024-04-25  9:26                               ` Yi Liu
2024-04-25 12:58                                 ` Alex Williamson
2024-04-26  9:01                                   ` Yi Liu
2024-04-19 13:59                 ` Jason Gunthorpe
2024-04-23  7:58                   ` Yi Liu
2024-04-23 12:05                     ` Jason Gunthorpe
2024-04-19 13:34           ` Jason Gunthorpe

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