From 97413cea1c48cc05d33db442d1c41d71c56c730e Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Sat, 19 Oct 2024 18:15:43 +0100 Subject: KVM: arm64: Add PSCI v1.3 SYSTEM_OFF2 function for hibernation 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 ensure that they preserve the virtual environment appropriately to allow the guest to resume safely (or bump the hardware_signature in the FACS to trigger a clean reboot instead). This feature is safe to enable unconditionally (in a subsequent commit) because it is exposed to userspace through the existing KVM_SYSTEM_EVENT_SHUTDOWN event, just with an additional flag which userspace can use to know that the instance intended hibernation instead of a plain power-off. As with SYSTEM_RESET2, there is only one type available (in this case HIBERNATE_OFF), and it is not explicitly reported to userspace through the event; userspace can get it from the registers if it cares). Signed-off-by: David Woodhouse Reviewed-by: Miguel Luis Link: https://lore.kernel.org/r/20241019172459.2241939-3-dwmw2@infradead.org [oliver: slight cleanup of comments] Signed-off-by: Oliver Upton --- Documentation/virt/kvm/api.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'Documentation/virt') diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index e32471977d0a..206cd0bc4ef4 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6855,6 +6855,10 @@ the first `ndata` items (possibly zero) of the data array are valid. the guest issued a SYSTEM_RESET2 call according to v1.1 of the PSCI specification. + - for arm64, data[0] is set to KVM_SYSTEM_EVENT_SHUTDOWN_FLAG_PSCI_OFF2 + if the guest issued a SYSTEM_OFF2 call according to v1.3 of the PSCI + specification. + - for RISC-V, data[0] is set to the value of the second argument of the ``sbi_system_reset`` call. @@ -6888,6 +6892,12 @@ either: - Deny the guest request to suspend the VM. See ARM DEN0022D.b 5.19.2 "Caller responsibilities" for possible return values. +Hibernation using the PSCI SYSTEM_OFF2 call is enabled when PSCI v1.3 +is enabled. If a guest invokes the PSCI SYSTEM_OFF2 function, KVM will +exit to userspace with the KVM_SYSTEM_EVENT_SHUTDOWN event type and with +data[0] set to KVM_SYSTEM_EVENT_SHUTDOWN_FLAG_PSCI_OFF2. The only +supported hibernate type for the SYSTEM_OFF2 function is HIBERNATE_OFF. + :: /* KVM_EXIT_IOAPIC_EOI */ -- cgit v1.3.1