Messages in this thread | | | Date | Thu, 16 Jun 2022 11:58:42 -0500 | Subject | Re: [PATCH 1/2] x86: notify hypervisor about guest entering s2idle state | From | "Limonciello, Mario" <> |
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On 6/16/2022 11:48, Sean Christopherson wrote: > On Wed, Jun 15, 2022, Grzegorz Jaszczyk wrote: >> pt., 10 cze 2022 o 16:30 Sean Christopherson <seanjc@google.com> napisał(a): >>> MMIO or PIO for the actual exit, there's nothing special about hypercalls. As for >>> enumerating to the guest that it should do something, why not add a new ACPI_LPS0_* >>> function? E.g. something like >>> >>> static void s2idle_hypervisor_notify(void) >>> { >>> if (lps0_dsm_func_mask > 0) >>> acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT_HYPERVISOR_NOTIFY >>> lps0_dsm_func_mask, lps0_dsm_guid); >>> } >> >> Great, thank you for your suggestion! I will try this approach and >> come back. Since this will be the main change in the next version, >> will it be ok for you to add Suggested-by: Sean Christopherson >> <seanjc@google.com> tag? > > If you want, but there's certainly no need to do so. But I assume you or someone > at Intel will need to get formal approval for adding another ACPI LPS0 function? > I.e. isn't there work to be done outside of the kernel before any patches can be > merged?
There are 3 different LPS0 GUIDs in use. An Intel one, an AMD (legacy) one, and a Microsoft one. They all have their own specs, and so if this was to be added I think all 3 need to be updated.
As this is Linux specific hypervisor behavior, I don't know you would be able to convince Microsoft to update theirs' either.
How about using s2idle_devops? There is a prepare() call and a restore() call that is set for each handler. The only consumer of this ATM I'm aware of is the amd-pmc driver, but it's done like a notification chain so that a bunch of drivers can hook in if they need to.
Then you can have this notification path and the associated ACPI device it calls out to be it's own driver.
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