linux-kernel - [PATCH 1/4] ACPICA: Do not flush cache for on entering S4 and S5

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Message-Id: <20211206122952.74139-2-kirill.shutemov@linux.intel.com>
Date:   Mon,  6 Dec 2021 15:29:49 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     rafael@...nel.org
Cc:     ak@...ux.intel.com, bp@...en8.de, dan.j.williams@...el.com,
        dave.hansen@...ux.intel.com, hpa@...or.com,
        kirill.shutemov@...ux.intel.com, knsathya@...nel.org,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, rjw@...ysocki.net,
        sathyanarayanan.kuppuswamy@...ux.intel.com, tglx@...utronix.de,
        tony.luck@...el.com, x86@...nel.org
Subject: [PATCH 1/4] ACPICA: Do not flush cache for on entering S4 and S5

According to the ACPI spec v6.4, section 16.2 the cache flushing is
required on entering to S1, S2, and S3. ACPICA code flushes 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
fixes the issue.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 drivers/acpi/acpica/hwesleep.c  | 3 ++-
 drivers/acpi/acpica/hwsleep.c   | 3 ++-
 drivers/acpi/acpica/hwxfsleep.c | 2 --
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/acpica/hwesleep.c b/drivers/acpi/acpica/hwesleep.c
index 808fdf54aeeb..ceb5a4292efa 100644
--- a/drivers/acpi/acpica/hwesleep.c
+++ b/drivers/acpi/acpica/hwesleep.c
@@ -104,7 +104,8 @@ acpi_status acpi_hw_extended_sleep(u8 sleep_state)
 
 	/* Flush caches, as per ACPI specification */
 
-	ACPI_FLUSH_CPU_CACHE();
+	if (sleep_state < ACPI_STATE_S4)
+		ACPI_FLUSH_CPU_CACHE();
 
 	status = acpi_os_enter_sleep(sleep_state, sleep_control, 0);
 	if (status == AE_CTRL_TERMINATE) {
diff --git a/drivers/acpi/acpica/hwsleep.c b/drivers/acpi/acpica/hwsleep.c
index 34a3825f25d3..ee094a3aaaab 100644
--- a/drivers/acpi/acpica/hwsleep.c
+++ b/drivers/acpi/acpica/hwsleep.c
@@ -110,7 +110,8 @@ acpi_status acpi_hw_legacy_sleep(u8 sleep_state)
 
 	/* Flush caches, as per ACPI specification */
 
-	ACPI_FLUSH_CPU_CACHE();
+	if (sleep_state < ACPI_STATE_S4)
+		ACPI_FLUSH_CPU_CACHE();
 
 	status = acpi_os_enter_sleep(sleep_state, pm1a_control, pm1b_control);
 	if (status == AE_CTRL_TERMINATE) {
diff --git a/drivers/acpi/acpica/hwxfsleep.c b/drivers/acpi/acpica/hwxfsleep.c
index e4cde23a2906..ba77598ee43e 100644
--- a/drivers/acpi/acpica/hwxfsleep.c
+++ b/drivers/acpi/acpica/hwxfsleep.c
@@ -162,8 +162,6 @@ acpi_status acpi_enter_sleep_state_s4bios(void)
 		return_ACPI_STATUS(status);
 	}
 
-	ACPI_FLUSH_CPU_CACHE();
-
 	status = acpi_hw_write_port(acpi_gbl_FADT.smi_command,
 				    (u32)acpi_gbl_FADT.s4_bios_request, 8);
 	if (ACPI_FAILURE(status)) {
-- 
2.32.0