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Re: Runstate hypercall and Linux KPTI issues
- To: Jan Beulich <jbeulich@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxx>
- From: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
- Date: Thu, 10 Sep 2020 14:04:52 +0000
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- Cc: Julien Grall <julien@xxxxxxx>, Stefano Stabellini <stefanos@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxx>, nd <nd@xxxxxxx>
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- Thread-topic: Runstate hypercall and Linux KPTI issues
> On 10 Sep 2020, at 15:00, Bertrand Marquis <Bertrand.Marquis@xxxxxxx> wrote:
>
>
>
>> On 10 Sep 2020, at 14:56, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>
>> On 10.09.2020 15:46, Bertrand Marquis wrote:
>>> Some open questions:
>>> - should we allow to register an area using both hypercalls or should it be
>>> exclusive ?
>>
>> I thought it was already clarified that to a certain degree both need
>> to remain usable at least in sequence, to allow transitioning control
>> between entirely independent entities (bootloader -> kernel -> dump-
>> kernel, for example).
>
> Sorry my wording was not clear here
>
> Should we allow to register 2 areas at the same time using both hypercalls
> (one with
> virtual address and one with physical address) or should they be exclusive ie
> one or
> the other but not both at the same time
>
>>
>>> - should we backport the support for this hypercall in older kernel
>>> releases ?
>>
>> It's a bug fix to KPTI, and as such ought to be at least eligible for
>> considering doing so?
>
> That will mean also backport in Linux. What should be the scope ?
>
> Bertrand
>
>>
>> Jan
>
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Sorry the disclaimer should not appear anymore, no idea what is going wrong on
our side here
Bertrand
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