From: Jason Gunthorpe <jgg@nvidia.com>
To: Samiullah Khawaja <skhawaja@google.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Kevin Tian <kevin.tian@intel.com>,
Dmytro Maluka <dmaluka@chromium.org>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] iommu/vt-d: Rework hitless PASID entry replacement
Date: Tue, 13 Jan 2026 16:56:51 -0400 [thread overview]
Message-ID: <20260113205651.GK812923@nvidia.com> (raw)
In-Reply-To: <CAAywjhSv56Y9rJLVdqV9N54c7S30ZUjyNh05xc-EW2+dS74GFQ@mail.gmail.com>
On Tue, Jan 13, 2026 at 11:27:30AM -0800, Samiullah Khawaja wrote:
> > - Update 'struct pasid_entry' with a union to support 128-bit
> > access via the newly added val128[4] array.
> > - Add pasid_support_hitless_replace() to determine if a transition
> > between an old and new entry is safe to perform atomically.
> > - For First-level/Nested translations: The first 128 bits (chunk 0)
> > must remain identical; chunk 1 is updated atomically.
>
> Looking at the specs, the DID is part of the first 128 bits (chunk 0),
> so I guess for the first level the hitless replacement would not be
> supported since each domain will have a different DID?
Ah, yeah, you wont be able to do the KHO replace thing when using a
first stage..
Jason
next prev parent reply other threads:[~2026-01-13 20:56 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-13 3:00 [PATCH 0/3] iommu/vt-d: Ensure atomicity in context and PASID entry updates Lu Baolu
2026-01-13 3:00 ` [PATCH 1/3] iommu/vt-d: Use 128-bit atomic updates for context entries Lu Baolu
2026-01-13 19:27 ` Dmytro Maluka
2026-01-14 5:14 ` Baolu Lu
2026-01-14 10:55 ` Dmytro Maluka
2026-01-15 2:26 ` Baolu Lu
2026-01-15 13:12 ` Jason Gunthorpe
2026-01-14 7:54 ` Tian, Kevin
2026-01-15 3:26 ` Baolu Lu
2026-01-15 5:59 ` Tian, Kevin
2026-01-15 13:23 ` Jason Gunthorpe
2026-01-16 5:19 ` Tian, Kevin
2026-01-16 14:33 ` Jason Gunthorpe
2026-01-13 3:00 ` [PATCH 2/3] iommu/vt-d: Clear Present bit before tearing down PASID entry Lu Baolu
2026-01-13 19:34 ` Dmytro Maluka
2026-01-14 5:38 ` Baolu Lu
2026-01-14 11:12 ` Dmytro Maluka
2026-01-15 2:45 ` Baolu Lu
2026-01-15 21:35 ` Dmytro Maluka
2026-01-16 6:06 ` Baolu Lu
2026-01-20 13:49 ` Dmytro Maluka
2026-01-14 7:32 ` Tian, Kevin
2026-01-14 8:27 ` Baolu Lu
2026-01-15 5:49 ` Tian, Kevin
2026-01-13 3:00 ` [PATCH 3/3] iommu/vt-d: Rework hitless PASID entry replacement Lu Baolu
2026-01-13 15:05 ` Jason Gunthorpe
2026-01-14 6:03 ` Baolu Lu
2026-01-13 19:27 ` Samiullah Khawaja
2026-01-13 20:56 ` Jason Gunthorpe [this message]
2026-01-14 5:45 ` Baolu Lu
2026-01-14 7:26 ` Tian, Kevin
2026-01-14 13:17 ` Jason Gunthorpe
2026-01-14 18:51 ` Samiullah Khawaja
2026-01-14 19:07 ` Jason Gunthorpe
2026-01-15 5:44 ` Tian, Kevin
2026-01-15 13:28 ` Jason Gunthorpe
2026-01-16 6:16 ` Tian, Kevin
2026-01-13 19:39 ` Dmytro Maluka
2026-01-13 20:06 ` Dmytro Maluka
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