[+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