From: David Woodhouse <d...@amazon.co.uk>
The PSCI v1.3 specification 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.
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
Acked-by: Rafael J. Wysocki <raf...@kernel.org>
---
drivers/firmware/psci/psci.c | 42 ++++++++++++++++++++++++++++++++++++
kernel/power/hibernate.c | 5 ++++-
2 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index 2328ca58bba6..8809455a61a6 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -78,6 +78,7 @@ 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)
{
@@ -333,6 +334,33 @@ static void psci_sys_poweroff(void)
invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
}
+#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.
+ */
+ if (system_entering_hibernation())
+ invoke_psci_fn(PSCI_FN_NATIVE(1_3, SYSTEM_OFF2),
+ 0 /*PSCI_1_3_OFF_TYPE_HIBERNATE_OFF*/, 0, 0);
+ return NOTIFY_DONE;
+}
+
+static int __init psci_hibernate_init(void)
+{
+ if (psci_system_off2_hibernate_supported) {
+ /* Higher priority than EFI shutdown, but only for hibernate */
+ register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
+ SYS_OFF_PRIO_FIRMWARE + 2,
+ psci_sys_hibernate, NULL);
+ }
+ return 0;
+}
+subsys_initcall(psci_hibernate_init);
+#endif
+
static int psci_features(u32 psci_func_id)
{
return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
@@ -364,6 +392,7 @@ static const struct {
PSCI_ID_NATIVE(1_1, SYSTEM_RESET2),
PSCI_ID(1_1, MEM_PROTECT),
PSCI_ID_NATIVE(1_1, MEM_PROTECT_CHECK_RANGE),
+ PSCI_ID_NATIVE(1_3, SYSTEM_OFF2),
};
static int psci_debugfs_read(struct seq_file *s, void *data)
@@ -525,6 +554,18 @@ 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 & PSCI_1_3_OFF_TYPE_HIBERNATE_OFF)
+ psci_system_off2_hibernate_supported = true;
+}
+
static void __init psci_init_system_suspend(void)
{
int ret;
@@ -655,6 +696,7 @@ 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 e35829d36039..1f87aa01ba44 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -685,8 +685,11 @@ static void power_down(void)
}
fallthrough;
case HIBERNATION_SHUTDOWN:
- if (kernel_can_power_off())
+ if (kernel_can_power_off()) {
+ entering_platform_hibernation = true;
kernel_power_off();
+ entering_platform_hibernation = false;
+ }
break;
}
kernel_halt();
--
2.44.0
