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x86/ACPI: invalidate all cache lines on ACPI C-state transitions

Message ID 20250525180052.1004-1-khaliidcaliy@gmail.com
State New
Headers show
Series x86/ACPI: invalidate all cache lines on ACPI C-state transitions | expand

Commit Message

Khalid Ali May 25, 2025, 6 p.m. UTC 
From: Khalid Ali <khaliidcaliy@gmail.com>

According to ACPI spec 2.4 and 2.5, upon C-state
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.

Signed-off-by: Khalid Ali <khaliidcaliy@gmail.com>
---
 arch/x86/kernel/acpi/cstate.c | 3 +++
 1 file changed, 3 insertions(+)
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Patch

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);
 }