linux-kernel - [PATCH AUTOSEL 4.14 46/56] ACPICA: Hardware: Do not flush CPU cache when entering S4 and S5

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Date:   Mon, 17 Jan 2022 21:48:58 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Bob Moore <robert.moore@...el.com>,
        Sasha Levin <sashal@...nel.org>, linux-acpi@...r.kernel.org,
        devel@...ica.org
Subject: [PATCH AUTOSEL 4.14 46/56] ACPICA: Hardware: Do not flush CPU cache when entering S4 and S5

From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>

[ Upstream commit 1d4e0b3abb168b2ee1eca99c527cffa1b80b6161 ]

ACPICA commit 3dd7e1f3996456ef81bfe14cba29860e8d42949e

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.

Link: https://github.com/acpica/acpica/commit/3dd7e1f3
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Bob Moore <robert.moore@...el.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/acpi/acpica/hwesleep.c  | 4 +++-
 drivers/acpi/acpica/hwsleep.c   | 4 +++-
 drivers/acpi/acpica/hwxfsleep.c | 2 --
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/acpica/hwesleep.c b/drivers/acpi/acpica/hwesleep.c
index 7f8c57177819f..45b392fa36657 100644
--- a/drivers/acpi/acpica/hwesleep.c
+++ b/drivers/acpi/acpica/hwesleep.c
@@ -138,7 +138,9 @@ 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 2c54d08b20ca6..9e50529bb3cc9 100644
--- a/drivers/acpi/acpica/hwsleep.c
+++ b/drivers/acpi/acpica/hwsleep.c
@@ -149,7 +149,9 @@ 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 827c3242225d9..b3c7736611908 100644
--- a/drivers/acpi/acpica/hwxfsleep.c
+++ b/drivers/acpi/acpica/hwxfsleep.c
@@ -223,8 +223,6 @@ 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);
 
-- 
2.34.1