From: "Arnd Bergmann" <arnd@arndb.de>
To: "Joerg Roedel" <joro@8bytes.org>,
"Suravee Suthikulpanit" <suravee.suthikulpanit@amd.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
"Robin Murphy" <robin.murphy@arm.com>,
vasant.hegde@amd.com, "Jason Gunthorpe" <jgg@nvidia.com>,
"Kevin Tian" <kevin.tian@intel.com>,
jon.grimm@amd.com, santosh.shukla@amd.com, pandoh@google.com,
kumaranand@google.com, "Uros Bizjak" <ubizjak@gmail.com>,
Linux-Arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH v9 03/10] asm/rwonce: Introduce [READ|WRITE]_ONCE() support for __int128
Date: Wed, 06 Nov 2024 09:55:06 +0100 [thread overview]
Message-ID: <323dcff2-6135-4b8a-85db-bccc315ddfdf@app.fastmail.com> (raw)
In-Reply-To: <ZyoP0IKVmxfesRU8@8bytes.org>
On Tue, Nov 5, 2024, at 13:30, Joerg Roedel wrote:
> On Fri, Nov 01, 2024 at 04:22:57PM +0000, Suravee Suthikulpanit wrote:
>> include/asm-generic/rwonce.h | 2 +-
>> include/linux/compiler_types.h | 8 +++++++-
>> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> This patch needs Cc:
>
> Arnd Bergmann <arnd@arndb.de>
> linux-arch@vger.kernel.org
>
It also needs an update to the comment about why this is safe:
>> +++ b/include/asm-generic/rwonce.h
>> @@ -33,7 +33,7 @@
>> * (e.g. a virtual address) and a strong prevailing wind.
>> */
>> #define compiletime_assert_rwonce_type(t) \
>> - compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \
>> + compiletime_assert(__native_word(t) || sizeof(t) == sizeof(__dword_type), \
>> "Unsupported access size for {READ,WRITE}_ONCE().")
As far as I can tell, 128-but words don't get stored atomically on
any architecture, so this seems wrong, because it would remove
the assertion on someone incorrectly using WRITE_ONCE() on a
128-bit variable.
Arnd
next prev parent reply other threads:[~2024-11-06 8:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-01 16:22 [PATCH v9 00/10] iommu/amd: Use 128-bit cmpxchg operation to update DTE Suravee Suthikulpanit
2024-11-01 16:22 ` [PATCH v9 01/10] iommu/amd: Misc ACPI IVRS debug info clean up Suravee Suthikulpanit
2024-11-01 16:22 ` [PATCH v9 02/10] iommu/amd: Disable AMD IOMMU if CMPXCHG16B feature is not supported Suravee Suthikulpanit
2024-11-01 16:22 ` [PATCH v9 03/10] asm/rwonce: Introduce [READ|WRITE]_ONCE() support for __int128 Suravee Suthikulpanit
2024-11-05 12:30 ` Joerg Roedel
2024-11-06 8:55 ` Arnd Bergmann [this message]
2024-11-06 10:01 ` Uros Bizjak
2024-11-06 13:40 ` Jason Gunthorpe
2024-11-07 10:01 ` Arnd Bergmann
2024-11-07 10:30 ` Uros Bizjak
2024-11-07 13:37 ` Jason Gunthorpe
2024-11-07 13:47 ` Uros Bizjak
2024-11-01 16:22 ` [PATCH v9 04/10] iommu/amd: Introduce struct ivhd_dte_flags to store persistent DTE flags Suravee Suthikulpanit
2024-11-01 16:22 ` [PATCH v9 05/10] iommu/amd: Introduce helper function to update 256-bit DTE Suravee Suthikulpanit
2024-11-01 16:23 ` [PATCH v9 06/10] iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers Suravee Suthikulpanit
2024-11-01 16:32 ` Jason Gunthorpe
2024-11-01 16:23 ` [PATCH v9 07/10] iommu/amd: Introduce helper function get_dte256() Suravee Suthikulpanit
2024-11-01 16:23 ` [PATCH v9 08/10] iommu/amd: Modify clear_dte_entry() to avoid in-place update Suravee Suthikulpanit
2024-11-01 16:23 ` [PATCH v9 09/10] iommu/amd: Lock DTE before updating the entry with WRITE_ONCE() Suravee Suthikulpanit
2024-11-01 16:23 ` [PATCH v9 10/10] iommu/amd: Remove amd_iommu_apply_erratum_63() Suravee Suthikulpanit
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=323dcff2-6135-4b8a-85db-bccc315ddfdf@app.fastmail.com \
--to=arnd@arndb.de \
--cc=iommu@lists.linux.dev \
--cc=jgg@nvidia.com \
--cc=jon.grimm@amd.com \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=kumaranand@google.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pandoh@google.com \
--cc=robin.murphy@arm.com \
--cc=santosh.shukla@amd.com \
--cc=suravee.suthikulpanit@amd.com \
--cc=ubizjak@gmail.com \
--cc=vasant.hegde@amd.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox