From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: kevin.tian@intel.com, yi.l.liu@intel.com, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] iommufd: Add devices_users to track the hw_pagetable usage by device
Date: Mon, 30 Jan 2023 11:02:25 -0400 [thread overview]
Message-ID: <Y9fcAdFxl7GVSH9r@nvidia.com> (raw)
In-Reply-To: <c1c65ce093a3b585546dd17a77949efbe03a81d9.1674939002.git.nicolinc@nvidia.com>
On Sat, Jan 28, 2023 at 01:18:09PM -0800, Nicolin Chen wrote:
> From: Yi Liu <yi.l.liu@intel.com>
>
> Currently, hw_pagetable tracks the attached devices using a device list.
> When attaching the first device to the kernel-managed hw_pagetable, it
> should be linked to IOAS. When detaching the last device from this hwpt,
> the link with IOAS should be removed too. And this first-or-last device
> check is done with list_empty(hwpt->devices).
>
> However, with a nested configuration, when a device is attached to the
> user-managed stage-1 hw_pagetable, it will be added to this user-managed
> hwpt's device list instead of the kernel-managed stage-2 hwpt's one. And
> this breaks the logic for a kernel-managed hw_pagetable link/disconnect
> to/from IOAS/IOPT. e.g. the stage-2 hw_pagetable would be linked to IOAS
> multiple times if multiple device is attached, but it will become empty
> as soon as one device detached.
Why this seems really weird to say.
The stage 2 is linked explicitly to the IOAS that drives it's
map/unmap
Why is there any implicit activity here? There should be no implicit
attach of the S2 to an IOAS ever.
Jason
next prev parent reply other threads:[~2023-01-30 15:02 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-28 21:18 [PATCH v2 0/3] iommufd: Remove iommufd_hw_pagetable_has_group Nicolin Chen
2023-01-28 21:18 ` [PATCH v2 1/3] iommufd: Add devices_users to track the hw_pagetable usage by device Nicolin Chen
2023-01-29 9:23 ` Tian, Kevin
2023-01-29 9:30 ` Nicolin Chen
2023-01-29 9:39 ` Tian, Kevin
2023-01-30 2:22 ` Liu, Yi L
2023-01-30 15:02 ` Jason Gunthorpe [this message]
2023-01-30 19:27 ` Nicolin Chen
2023-01-30 19:50 ` Jason Gunthorpe
2023-01-30 20:04 ` Nicolin Chen
2023-01-30 20:35 ` Jason Gunthorpe
2023-01-30 20:53 ` Nicolin Chen
2023-02-01 7:48 ` Nicolin Chen
2023-02-02 9:12 ` Nicolin Chen
2023-02-07 4:19 ` Liu, Yi L
2023-02-01 6:57 ` Nicolin Chen
2023-02-01 7:56 ` Nicolin Chen
2023-02-01 15:53 ` Jason Gunthorpe
2023-02-01 17:46 ` Nicolin Chen
2023-02-01 18:37 ` Jason Gunthorpe
2023-02-01 19:25 ` Nicolin Chen
2023-02-01 20:00 ` Jason Gunthorpe
2023-02-01 21:18 ` Nicolin Chen
2023-02-02 7:28 ` Nicolin Chen
2023-02-02 15:03 ` Jason Gunthorpe
2023-02-07 4:27 ` Liu, Yi L
2023-01-28 21:18 ` [PATCH v2 2/3] iommufd/device: Make hwpt_list list_add/del symmetric Nicolin Chen
2023-01-29 9:24 ` Tian, Kevin
2023-01-29 9:31 ` Nicolin Chen
2023-01-30 14:59 ` Jason Gunthorpe
2023-01-30 19:03 ` Nicolin Chen
2023-01-30 19:07 ` Jason Gunthorpe
2023-01-30 19:38 ` Nicolin Chen
2023-01-28 21:18 ` [PATCH v2 3/3] iommufd/device: Change iommufd_hw_pagetable_has_group to device centric Nicolin Chen
2023-01-29 9:37 ` Tian, Kevin
2023-01-29 10:38 ` Nicolin Chen
2023-01-30 0:44 ` Tian, Kevin
2023-01-30 10:22 ` Nicolin Chen
2023-02-01 3:07 ` Tian, Kevin
2023-02-01 6:49 ` Baolu Lu
2023-02-01 6:59 ` Tian, Kevin
2023-02-01 7:20 ` Nicolin Chen
2023-02-02 6:32 ` Tian, Kevin
2023-02-02 6:36 ` Nicolin Chen
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