From: Jason Gunthorpe <jgg@ziepe.ca>
To: Pranjal Shrivastava <praan@google.com>
Cc: David Matlack <dmatlack@google.com>,
Samiullah Khawaja <skhawaja@google.com>,
David Woodhouse <dwmw2@infradead.org>,
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>,
Alex Williamson <alex@shazbot.org>, Shuah Khan <shuah@kernel.org>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, Saeed Mahameed <saeedm@nvidia.com>,
Adithya Jayachandran <ajayachandra@nvidia.com>,
Parav Pandit <parav@nvidia.com>,
Leon Romanovsky <leonro@nvidia.com>, William Tu <witu@nvidia.com>,
Pratyush Yadav <pratyush@kernel.org>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Andrew Morton <akpm@linux-foundation.org>,
Chris Li <chrisl@kernel.org>, Vipin Sharma <vipinsh@google.com>,
YiFei Zhu <zhuyifei@google.com>
Subject: Re: [PATCH v2 02/16] iommu: Implement IOMMU Live update FLB callbacks
Date: Sat, 23 May 2026 10:29:56 -0300 [thread overview]
Message-ID: <20260523132956.GG7702@ziepe.ca> (raw)
In-Reply-To: <agr9ggdY3GYltteV@google.com>
On Mon, May 18, 2026 at 11:52:34AM +0000, Pranjal Shrivastava wrote:
> On Fri, May 01, 2026 at 09:45:19PM +0000, David Matlack wrote:
>
> [...]
>
> > > +
> > > +/**
> > > + * struct iommu_hdr_ser - Common header for all serialized IOMMU objects
> > > + * @ref_count: Reference count for the object
> > > + * @deleted: Flag indicating if the object is deleted
> > > + * @incoming: Flag indicating if the object was preserved in previous kernel
> > > + */
> > > +struct iommu_hdr_ser {
> > > + u32 ref_count;
> > > + u32 deleted:1;
> > > + u32 incoming:1;
> >
> > Are C bitfields safe to use in Live Update ABI?
> >
>
> AFAIU, they aren't. The C standard does not dictate how bitfields are
> packed into their underlying types (e.g., whether they are packed MSB to
> LSB or vice-versa), making them highly dependent on the compiler and arch
> endianness.
Bitfield are defined in the SYSV UNIX ELF ABIs, they are stable for
kexec, but variable across arches how they lay out in memory.
Jason
next prev parent reply other threads:[~2026-05-23 13:29 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 17:56 [PATCH v2 00/16] iommu: Add live update state preservation Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 01/16] liveupdate: luo_file: Add internal APIs for file preservation Samiullah Khawaja
2026-05-18 11:40 ` Pranjal Shrivastava
2026-05-18 19:08 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 02/16] iommu: Implement IOMMU Live update FLB callbacks Samiullah Khawaja
2026-05-01 21:45 ` David Matlack
2026-05-18 11:52 ` Pranjal Shrivastava
2026-05-18 14:10 ` Pratyush Yadav
2026-05-18 15:08 ` Pranjal Shrivastava
2026-05-23 13:29 ` Jason Gunthorpe [this message]
2026-05-18 12:33 ` Pranjal Shrivastava
2026-05-18 17:20 ` Samiullah Khawaja
2026-05-18 17:32 ` Pranjal Shrivastava
2026-05-18 17:06 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 03/16] iommu: Implement IOMMU domain preservation Samiullah Khawaja
2026-05-01 22:08 ` David Matlack
2026-05-04 18:33 ` Samiullah Khawaja
2026-05-18 13:13 ` Pranjal Shrivastava
2026-05-18 18:55 ` Samiullah Khawaja
2026-05-18 21:36 ` Pranjal Shrivastava
2026-04-27 17:56 ` [PATCH v2 04/16] iommu: Implement device and IOMMU HW preservation Samiullah Khawaja
2026-05-01 22:42 ` David Matlack
2026-05-04 19:06 ` Samiullah Khawaja
2026-05-07 2:07 ` Baolu Lu
2026-05-07 18:47 ` Samiullah Khawaja
2026-05-18 14:01 ` Pranjal Shrivastava
2026-05-18 18:33 ` Samiullah Khawaja
2026-05-18 13:55 ` Pranjal Shrivastava
2026-05-18 18:44 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 05/16] iommu/pages: Add APIs to preserve/unpreserve/restore iommu pages Samiullah Khawaja
2026-05-18 14:23 ` Pranjal Shrivastava
2026-05-18 17:22 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 06/16] iommupt: Implement preserve/unpreserve/restore callbacks Samiullah Khawaja
2026-05-07 2:55 ` Baolu Lu
2026-05-07 18:40 ` Samiullah Khawaja
2026-05-19 13:15 ` Pranjal Shrivastava
2026-05-19 17:14 ` Samiullah Khawaja
2026-05-23 13:33 ` Jason Gunthorpe
2026-04-27 17:56 ` [PATCH v2 07/16] iommu/vt-d: Implement device and iommu preserve/unpreserve ops Samiullah Khawaja
2026-05-07 6:25 ` Baolu Lu
2026-05-08 2:36 ` Samiullah Khawaja
2026-05-18 20:32 ` Samiullah Khawaja
2026-05-19 14:40 ` Pranjal Shrivastava
2026-05-19 18:26 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 08/16] iommu: Add APIs to get iommu and device preserved state Samiullah Khawaja
2026-05-19 15:52 ` Pranjal Shrivastava
2026-05-20 17:24 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 09/16] iommu/vt-d: Restore IOMMU state and reclaimed domain ids Samiullah Khawaja
2026-05-07 9:05 ` Baolu Lu
2026-05-07 17:35 ` Samiullah Khawaja
2026-05-19 21:46 ` Pranjal Shrivastava
2026-05-20 18:02 ` Pranjal Shrivastava
2026-05-20 19:59 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 10/16] iommu: Restore and reattach preserved domains to devices Samiullah Khawaja
2026-05-07 13:54 ` Baolu Lu
2026-05-07 16:52 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 11/16] iommu/vt-d: preserve PASID table of preserved device Samiullah Khawaja
2026-05-08 6:05 ` Baolu Lu
2026-05-11 18:45 ` Samiullah Khawaja
2026-05-12 11:32 ` Baolu Lu
2026-05-19 22:35 ` Pranjal Shrivastava
2026-05-20 18:13 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 12/16] iommufd: Implement ioctl to mark HWPT for preservation Samiullah Khawaja
2026-05-19 23:05 ` Pranjal Shrivastava
2026-05-20 19:50 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 13/16] iommufd: Persist iommu hardware pagetables for live update Samiullah Khawaja
2026-05-20 0:00 ` Pranjal Shrivastava
2026-05-20 19:40 ` Samiullah Khawaja
2026-05-22 16:01 ` Pranjal Shrivastava
2026-05-22 19:29 ` Pranjal Shrivastava
2026-04-27 17:56 ` [PATCH v2 14/16] iommufd: Add APIs to preserve/unpreserve a vfio cdev Samiullah Khawaja
2026-05-20 0:46 ` Pranjal Shrivastava
2026-04-27 17:56 ` [PATCH v2 15/16] vfio/pci: Preserve the iommufd state of the " Samiullah Khawaja
2026-05-20 0:57 ` Pranjal Shrivastava
2026-05-20 19:54 ` Samiullah Khawaja
2026-04-27 17:56 ` [PATCH v2 16/16] iommufd/selftest: Add test to verify iommufd preservation Samiullah Khawaja
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