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Re: [Xen-devel] [PATCH 1/2] x86/shim: suspend and resume platform time correctly

On 04/02/2020 17:43, Igor Druzhinin wrote:
> On 04/02/2020 17:17, Roger Pau Monné wrote:
>> On Tue, Feb 04, 2020 at 03:40:24PM +0000, Igor Druzhinin wrote:
>>> Similarly to S3, platform time needs to be saved on guest suspend
>>> and restored on resume respectively. This should account for expected
>>> jumps in PV clock counter value after resume. time_suspend/resume()
>>> are safe to use in PVH setting as is since any existing operations
>>> with PIT that they do would simply be ignored there.
>> There's also an attempt to fiddle with HPET, which I think it's just a
>> no-op.
>> Just to be on the safe side it might be better to pass a new parameter
>> to time_resume in order to signal whether PIT/HPET should even be
>> attempted to be resumed?
> Both of preinit_pit() and _disable_pit_irq() already called in PV shim
> during boot. So it might be better to include a condition right inside
> them to cover that case as well.

On second thought, it might not be exactly true that those devices are
non-present (at least for potential PV-in-HVM case).
So I'll leave it as is for v2.


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