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Re: [PATCH v2 for-4.18?] x86: support data operand independent timing mode
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Henry Wang <Henry.Wang@xxxxxxx>
- Date: Mon, 25 Sep 2023 07:53:06 +0000
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- Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, 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 v2 for-4.18?] x86: support data operand independent timing mode
Hi Jan,
> On Sep 12, 2023, at 08:48, Henry Wang <Henry.Wang@xxxxxxx> wrote:
>
> Hi Jan,
>
>> On Sep 11, 2023, at 23:01, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>
>> [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/software-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 4.18. It
>> may, however, also be viewed as security relevant, which is why I'd like
>> to propose to at least consider it.
>
> Fine with me if this patch can be properly reviewed on time, because of
> the security relevance.
Based on this, if this patch can be properly reviewed before we release
4.18, please feel free to add:
Release-acked-by: Henry Wang <Henry.Wang@xxxxxxx>
Kind regards,
Henry
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