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RE: [PATCH for-4.17?] x86: support data operand independent timing mode
- To: Jan Beulich <jbeulich@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Henry Wang <Henry.Wang@xxxxxxx>
- Date: Fri, 16 Sep 2022 01:28:18 +0000
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
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- Thread-topic: [PATCH for-4.17?] x86: support data operand independent timing mode
Hi Jan,
> -----Original Message-----
> Subject: [PATCH for-4.17?] x86: support data operand independent timing
> mode
>
> [1] specifies a long list of instructions which are intended to exhibit
> timing behavior independent of the data they operate on. On certain
> hardware this independence is optional, controlled by a bit in a new
> MSR. Provide a command line option to control the mode Xen and its
> guests are to operate in, with a build time control over the default.
> Longer term we may want to allow guests to control this.
>
> Since Arm64 supposedly also has such a control, put command line option
> and Kconfig control in common files.
>
> [1]
> https://www.intel.com/content/www/us/en/developer/articles/technical/so
> ftware-security-guidance/best-practices/data-operand-independent-timing-
> isa-guidance.html
>
> Requested-by: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> This may be viewed as a new feature, and hence be too late for 4.17. It
> may, however, also be viewed as security relevant, which is why I'd like
> to propose to at least consider it.
Based on the discussion in this thread so far, I think people would view
this patch as a security relevant patch, so I guess without strong
objection to merge this in 4.17, it is fine to add this in the release (with
proper review, of course).
Kind regards,
Henry
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