Revert "intel_idle: Add a "Long HLT" C1 state for the VM guest mode"

This reverts commit 0fac214bb75e ("intel_idle: Add a "Long HLT" C1 state
for the VM guest mode"), because there is a coding mistake in it and its
validity is questioned.

Link: https://lore.kernel.org/all/20230711132553.GN3062772@hirez.programming.kicks-ass.net
Requested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 34201d7..a80e1f5 100644 (file)
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1288,13 +1288,6 @@ static struct cpuidle_state vmguest_cstates[] __initdata = {
                .target_residency = 10,
                .enter = &intel_idle_hlt, },
        {
-               .name = "C1L",
-               .desc = "Long HLT",
-               .flags = MWAIT2flg(0x00) | CPUIDLE_FLAG_TLB_FLUSHED,
-               .exit_latency = 5,
-               .target_residency = 200,
-               .enter = &intel_idle_hlt, },
-       {
                .enter = NULL }
 };
 
@@ -2137,45 +2130,6 @@ static void __init intel_idle_cpuidle_devices_uninit(void)
                cpuidle_unregister_device(per_cpu_ptr(intel_idle_cpuidle_devices, i));
 }
 
-/*
- * Match up the latency and break even point of the bare metal (cpu based)
- * states with the deepest VM available state.
- *
- * We only want to do this for the deepest state, the ones that has
- * the TLB_FLUSHED flag set on the .
- *
- * All our short idle states are dominated by vmexit/vmenter latencies,
- * not the underlying hardware latencies so we keep our values for these.
- */
-static void matchup_vm_state_with_baremetal(void)
-{
-       int cstate;
-
-       for (cstate = 0; cstate < CPUIDLE_STATE_MAX; ++cstate) {
-               int matching_cstate;
-
-               if (intel_idle_max_cstate_reached(cstate))
-                       break;
-
-               if (!cpuidle_state_table[cstate].enter)
-                       break;
-
-               if (!(cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_TLB_FLUSHED))
-                       continue;
-
-               for (matching_cstate = 0; matching_cstate < CPUIDLE_STATE_MAX; ++matching_cstate) {
-                       if (!icpu->state_table[matching_cstate].enter)
-                               break;
-                       if (icpu->state_table[matching_cstate].exit_latency > cpuidle_state_table[cstate].exit_latency) {
-                               cpuidle_state_table[cstate].exit_latency = icpu->state_table[matching_cstate].exit_latency;
-                               cpuidle_state_table[cstate].target_residency = icpu->state_table[matching_cstate].target_residency;
-                       }
-               }
-
-       }
-}
-
-
 static int __init intel_idle_vminit(const struct x86_cpu_id *id)
 {
        int retval;
@@ -2191,15 +2145,6 @@ static int __init intel_idle_vminit(const struct x86_cpu_id *id)
        if (!intel_idle_cpuidle_devices)
                return -ENOMEM;
 
-       /*
-        * We don't know exactly what the host will do when we go idle, but as a worst estimate
-        * we can assume that the exit latency of the deepest host state will be hit for our
-        * deep (long duration) guest idle state.
-        * The same logic applies to the break even point for the long duration guest idle state.
-        * So lets copy these two properties from the table we found for the host CPU type.
-        */
-       matchup_vm_state_with_baremetal();
-
        intel_idle_cpuidle_driver_init(&intel_idle_driver);
 
        retval = cpuidle_register_driver(&intel_idle_driver);