[+Ard, Sami, for EFI] On Thu, Oct 31, 2024 at 06:55:43PM +0100, Lorenzo Pieralisi wrote: > On Sat, Oct 19, 2024 at 06:15:47PM +0100, David Woodhouse wrote: > > [...] > > > +#ifdef CONFIG_HIBERNATION > > +static int psci_sys_hibernate(struct sys_off_data *data) > > +{ > > + /* > > + * Zero is an acceptable alternative to PSCI_1_3_OFF_TYPE_HIBERNATE_OFF > > + * and is supported by hypervisors implementing an earlier version > > + * of the pSCI v1.3 spec. > > + */ > > It is obvious but with this patch applied a host kernel would start executing > SYSTEM_OFF2 too if supported in firmware to hibernate, it is not a hypervisor > only code path. > > Related to that: is it now always safe to override > > commit 60c0d45a7f7a ("efi/arm64: use UEFI for system reset and poweroff") > > for hibernation ? It is not very clear to me why overriding PSCI for > poweroff was the right thing to do - tried to follow that patch history but > the question remains (it is related to UpdateCapsule() but I don't know > how that applies to the hibernation use case). RFC: It is unclear to me what happens in current mainline if we try to hibernate with EFI runtime services enabled and a capsule update pending (we issue EFI ResetSystem(EFI_RESET_SHUTDOWN,..) which might not be compatible with the reset required by the pending capsule update request) what happens in this case I don't know but at least the choice is all contained in EFI firmware. Then if in the same scenario now we are switching to PSCI SYSTEM_OFF2 for the hibernate reset I suspect that what happens to the in-flight capsule update requests strictly depends on what "reset" PSCI SYSTEM_OFF2 will end up doing ? I think this is just a corner case and it is unlikely it has been ever tested (is it even possible ? Looking at EFI folks) - it would be good to clarify it at least to make sure we understand this code path. Thanks, Lorenzo