On Fri, May 30, 2025 at 7:54 PM Khalid Ali <khaliidcaliy@xxxxxxxxx> wrote: > > From: Khalid Ali <khaliidcaliy@xxxxxxxxx> > > According to ACPI spec 6.4 and 6.5, upon C-state Which section? > transitions (specifically C2 and C3) it is required and explicitly > mentioned to invalidate and writeback all modified cache line using > WBINVD. > > However the current ACPI C-state entry using monitor/mwait instructions > it have been used CLFLUSH by flushing the cache line associated by > monitored address. That what all about this patch addresses, > invalidating all cache lines instead of single cache line. > > Let me know if there any reason and decisions behind the current > implementation. I think that Peter has answered this already. Anyway: Is there any practical reason to make this change? For instance, any system that doesn't work before it and works after it? > Signed-off-by: Khalid Ali <khaliidcaliy@xxxxxxxxx> > --- > arch/x86/kernel/acpi/cstate.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c > index d5ac34186555..eb3d435e08ad 100644 > --- a/arch/x86/kernel/acpi/cstate.c > +++ b/arch/x86/kernel/acpi/cstate.c > @@ -222,6 +222,9 @@ void __cpuidle acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx) > struct cstate_entry *percpu_entry; > > percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu); > + /* flush and invalidate all modified cache line on C3 and C2 state entry*/ > + if (cx->type == ACPI_STATE_C3 || cx->type == ACPI_STATE_C2) > + wbinvd(); > mwait_idle_with_hints(percpu_entry->states[cx->index].eax, > percpu_entry->states[cx->index].ecx); > } > --
