Hardware: Do not flush CPU cache when entering S4 and S5

According to ACPI 6.4, Section 16.2, the CPU cache flushing is
required on entering to S1, S2, and S3, but the ACPICA code
flushes the CPU cache regardless of the sleep state.

Blind cache flush on entering S5 causes problems for TDX.

Flushing happens with WBINVD that is not supported in the TDX
environment.

TDX only supports S5 and adjusting ACPICA code to conform to the
spec more strictly fixes the issue.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

source/components/hardware/hwesleep.c

@@ -261,7 +261,10 @@ AcpiHwExtendedSleep (
 
     /* Flush caches, as per ACPI specification */
 
-    ACPI_FLUSH_CPU_CACHE ();
+    if (SleepState < ACPI_STATE_S4)
+    {
+        ACPI_FLUSH_CPU_CACHE ();
+    }
 
     Status = AcpiOsEnterSleep (SleepState, SleepControl, 0);
     if (Status == AE_CTRL_TERMINATE)

source/components/hardware/hwsleep.c

@@ -262,7 +262,10 @@ AcpiHwLegacySleep (
 
     /* Flush caches, as per ACPI specification */
 
-    ACPI_FLUSH_CPU_CACHE ();
+    if (SleepState < ACPI_STATE_S4)
+    {
+        ACPI_FLUSH_CPU_CACHE ();
+    }
 
     Status = AcpiOsEnterSleep (SleepState, Pm1aControl, Pm1bControl);
     if (Status == AE_CTRL_TERMINATE)

source/components/hardware/hwxfsleep.c

@@ -353,8 +353,6 @@ AcpiEnterSleepStateS4bios (
         return_ACPI_STATUS (Status);
     }
 
-    ACPI_FLUSH_CPU_CACHE ();
-
     Status = AcpiHwWritePort (AcpiGbl_FADT.SmiCommand,
         (UINT32) AcpiGbl_FADT.S4BiosRequest, 8);
     if (ACPI_FAILURE (Status))