From 8f8110f55c1aaab1685525c314c260fe755dfa47 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 11 Mar 2024 13:29:02 +0000 Subject: [PATCH] arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate The PSCI v1.3 specification (alpha) adds support for a SYSTEM_OFF2 function which is analogous to ACPI S4 state. This will allow hosting environments to determine that a guest is hibernated rather than just powered off, and handle that state appropriately on subsequent launches. Since commit 60c0d45a7f7a ("efi/arm64: use UEFI for system reset and poweroff") the EFI shutdown method is deliberately preferred over PSCI or other methods. So register a SYS_OFF_MODE_POWER_OFF handler which *only* handles the hibernation, leaving the original PSCI SYSTEM_OFF as a last resort via the legacy pm_power_off function pointer. The hibernation code already exports a system_entering_hibernation() function which is be used by the higher-priority handler to check for hibernation. That existing function just returns the value of a static boolean variable from hibernate.c, which was previously only set in the hibernation_platform_enter() code path. Set the same flag in the simpler code path around the call to kernel_power_off() too. An alternative way to hook SYSTEM_OFF2 into the hibernation code would be to register a platform_hibernation_ops structure with an ->enter() method which makes the new SYSTEM_OFF2 call. But that would have the unwanted side-effect of making hibernation take a completely different code path in hibernation_platform_enter(), invoking a lot of special dpm callbacks. Another option might be to add a new SYS_OFF_MODE_HIBERNATE mode, with fallback to SYS_OFF_MODE_POWER_OFF. Or to use the sys_off_data to indicate whether the power off is for hibernation. But this version works and is relatively simple. [5.15: Override pm_power_off() like EFI does (and *after* EFI does).] Signed-off-by: David Woodhouse Acked-by: Rafael J. Wysocki --- drivers/firmware/psci/psci.c | 39 ++++++++++++++++++++++++++++++++++++ kernel/power/hibernate.c | 5 ++++- 2 files changed, 43 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c index cfb448eabdaa2..8aaa8dc4a08b4 100644 --- a/drivers/firmware/psci/psci.c +++ b/drivers/firmware/psci/psci.c @@ -77,6 +77,7 @@ struct psci_0_1_function_ids get_psci_0_1_function_ids(void) static u32 psci_cpu_suspend_feature; static bool psci_system_reset2_supported; +static bool psci_system_off2_hibernate_supported; static inline bool psci_has_ext_power_state(void) { @@ -324,6 +325,31 @@ static void psci_sys_poweroff(void) invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0); } +#ifdef CONFIG_HIBERNATION +static void (*psci_orig_pm_power_off)(void); + +static void psci_sys_hibernate(void) +{ + if (system_entering_hibernation()) + invoke_psci_fn(PSCI_FN_NATIVE(1_3, SYSTEM_OFF2), + PSCI_1_3_HIBERNATE_TYPE_OFF, 0, 0); + if (psci_orig_pm_power_off) + psci_orig_pm_power_off(); + psci_sys_poweroff(); +} + +static int __init psci_hibernate_init(void) +{ + /* This runs *later* than efi_shutdown_init */ + if (psci_system_off2_hibernate_supported) { + psci_orig_pm_power_off = pm_power_off; + pm_power_off = psci_sys_hibernate; + } + return 0; +} +late_initcall(psci_hibernate_init); +#endif + static int __init psci_features(u32 psci_func_id) { return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES, @@ -385,6 +411,18 @@ static void __init psci_init_system_reset2(void) psci_system_reset2_supported = true; } +static void __init psci_init_system_off2(void) +{ + int ret; + + ret = psci_features(PSCI_FN_NATIVE(1_3, SYSTEM_OFF2)); + if (ret < 0) + return; + + if (ret & BIT(PSCI_1_3_HIBERNATE_TYPE_OFF)) + psci_system_off2_hibernate_supported = true; +} + static void __init psci_init_system_suspend(void) { int ret; @@ -515,6 +553,7 @@ static int __init psci_probe(void) psci_init_cpu_suspend(); psci_init_system_suspend(); psci_init_system_reset2(); + psci_init_system_off2(); kvm_init_hyp_services(); } diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index 9abc73d500fbf..d584e53c72141 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -664,8 +664,11 @@ static void power_down(void) hibernation_platform_enter(); fallthrough; case HIBERNATION_SHUTDOWN: - if (pm_power_off) + if (pm_power_off) { + entering_platform_hibernation = true; kernel_power_off(); + entering_platform_hibernation = false; + } break; } kernel_halt(); -- 2.49.0