6.12-stable review patch. If anyone has any objections, please let me know.
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From: Giovanni Gherdovich ggherdovich@suse.cz
[ Upstream commit 9e9b893404d43894d69a18dd2fc8fcf1c36abb7e ]
Prior to commit 496121c02127 ("ACPI: processor: idle: Allow probing on platforms with one ACPI C-state"), the acpi_idle driver wouldn't load on systems without a valid C-State at least as deep as C2.
The behavior was desirable for guests on hypervisors such as VMWare ESXi, which by default don't have the _CST ACPI method, and set the C2 and C3 latencies to 101 and 1001 microseconds respectively via the FADT, to signify they're unsupported.
Since the above change though, these virtualized deployments end up loading acpi_idle, and thus entering the default C1 C-State set by acpi_processor_get_power_info_default(); this is undesirable for a system that's communicating to the OS it doesn't want C-States (missing _CST, and invalid C2/C3 in FADT).
Make acpi_processor_get_power_info_fadt() return -ENODEV in that case, so that acpi_processor_get_cstate_info() exits early and doesn't set pr->flags.power = 1.
Fixes: 496121c02127 ("ACPI: processor: idle: Allow probing on platforms with one ACPI C-state") Signed-off-by: Giovanni Gherdovich ggherdovich@suse.cz Reviewed-by: Zhang Rui rui.zhang@intel.com Link: https://patch.msgid.link/20250328143040.9348-1-ggherdovich@suse.cz [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/processor_idle.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 831fa4a121598..0888e4d618d53 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -268,6 +268,10 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr) ACPI_CX_DESC_LEN, "ACPI P_LVL3 IOPORT 0x%x", pr->power.states[ACPI_STATE_C3].address);
+ if (!pr->power.states[ACPI_STATE_C2].address && + !pr->power.states[ACPI_STATE_C3].address) + return -ENODEV; + return 0; }