Messages in this thread | | | Subject | Re: [RFC 0/3] Integrate Support for self-save and determine | From | Pratik Sampat <> | Date | Mon, 6 Jan 2020 15:15:30 +0530 |
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Thanks for your comments Ram, >> A list of preferred SPRs are maintained in the kernel which contains two >> properties: >> 1. supported_mode: Helps in identifying if it strictly supports self >> save or restore or both. > Will be good to capture the information that, 'supported_mode' gets > initialized using the information from the device tree. > >> 2. preferred_mode: Calls out what mode is preferred for each SPR. It >> could be strictly self save or restore, or it can also >> determine the preference of mode over the other if both >> are present by encapsulating the other in bitmask from >> LSB to MSB. > and 'preferred_mode' is statically initialized. > Sure thing, I'll mention that.
>> Below is a table to show the Scenario::Consequence when the self save and >> self restore modes are available or disabled in different combinations as >> perceived from the device tree thus giving complete backwards compatibly >> regardless of an older firmware running a newer kernel or vise-versa. >> >> SR = Self restore; SS = Self save >> >> .-----------------------------------.----------------------------------------. >> | Scenario | Consequence | >> :-----------------------------------+----------------------------------------: >> | Legacy Firmware. No SS or SR node | Self restore is called for all | >> | | supported SPRs | >> :-----------------------------------+----------------------------------------: >> | SR: !active SS: !active | Deep stop states disabled | >> :-----------------------------------+----------------------------------------: >> | SR: active SS: !active | Self restore is called for all | >> | | supported SPRs | >> :-----------------------------------+----------------------------------------: >> | SR: active SS: active | Goes through the preferences for each | >> | | SPR and executes of the modes | >> | | accordingly. Currently, Self restore is| >> | | called for all the SPRs except PSSCR | >> | | which is self saved | >> :-----------------------------------+----------------------------------------: >> | SR: active(only HID0) SS: active | Self save called for all supported | >> | | registers expect HID0 (as HID0 cannot | >> | | be self saved currently) | > Not clear, how this will be conveyed to the hypervisor? Through the > device tree or through some other means? > This information will be conveyed through the device tree. I'll frame a sentence that makes this more explicit.
>> :-----------------------------------+----------------------------------------: >> | SR: !active SS: active | currently will disable deep states as | >> | | HID0 is needed to be self restored and | >> | | cannot be self saved | >> '-----------------------------------'----------------------------------------' >> >> Pratik Rajesh Sampat (3): >> powerpc/powernv: Interface to define support and preference for a SPR >> powerpc/powernv: Introduce Self save support >> powerpc/powernv: Parse device tree, population of SPR support >> >> arch/powerpc/include/asm/opal-api.h | 3 +- >> arch/powerpc/include/asm/opal.h | 1 + >> arch/powerpc/platforms/powernv/idle.c | 431 ++++++++++++++++++--- >> arch/powerpc/platforms/powernv/opal-call.c | 1 + >> 4 files changed, 379 insertions(+), 57 deletions(-) >> >> -- >> 2.21.0
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