PM: hibernate: Honour ACPI hardware signature by default for virtual …

…guests The ACPI specification says that OSPM should refuse to restore from hibernate if the hardware signature changes, and should boot from scratch. However, real BIOSes often vary the hardware signature in cases where we *do* want to resume from hibernate, so Linux doesn't follow the spec by default. However, in a virtual environment there's no reason for the VMM to vary the hardware signature *unless* it wants to trigger a clean reboot as defined by the ACPI spec. So enable the check by default if a hypervisor is detected. Signed-off-by: David Woodhouse <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]>
rountree · Mar 16, 2022 · f6c46b1 · f6c46b1
1 parent a759de6
commit f6c46b1
Show file tree

Hide file tree

Showing 3 changed files with 25 additions and 11 deletions.
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
@@ -15,6 +15,7 @@
 #include <asm/desc.h>
 #include <asm/cacheflush.h>
 #include <asm/realmode.h>
+#include <asm/hypervisor.h>
 
 #include <linux/ftrace.h>
 #include "../../realmode/rm/wakeup.h"
@@ -140,9 +141,9 @@ static int __init acpi_sleep_setup(char *str)
 			acpi_realmode_flags |= 4;
 #ifdef CONFIG_HIBERNATION
 		if (strncmp(str, "s4_hwsig", 8) == 0)
-			acpi_check_s4_hw_signature(1);
+			acpi_check_s4_hw_signature = 1;
 		if (strncmp(str, "s4_nohwsig", 10) == 0)
-			acpi_check_s4_hw_signature(0);
+			acpi_check_s4_hw_signature = 0;
 #endif
 		if (strncmp(str, "nonvs", 5) == 0)
 			acpi_nvs_nosave();
@@ -160,3 +161,21 @@ static int __init acpi_sleep_setup(char *str)
 }
 
 __setup("acpi_sleep=", acpi_sleep_setup);
+
+#if defined(CONFIG_HIBERNATION) && defined(CONFIG_HYPERVISOR_GUEST)
+static int __init init_s4_sigcheck(void)
+{
+	/*
+	 * If running on a hypervisor, honour the ACPI specification
+	 * by default and trigger a clean reboot when the hardware
+	 * signature in FACS is changed after hibernation.
+	 */
+	if (acpi_check_s4_hw_signature == -1 &&
+	    !hypervisor_is_type(X86_HYPER_NATIVE))
+		acpi_check_s4_hw_signature = 1;
+
+	return 0;
+}
+/* This must happen before acpi_init() which is a subsys initcall */
+arch_initcall(init_s4_sigcheck);
+#endif
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
@@ -869,12 +869,7 @@ static inline void acpi_sleep_syscore_init(void) {}
 #ifdef CONFIG_HIBERNATION
 static unsigned long s4_hardware_signature;
 static struct acpi_table_facs *facs;
-static int sigcheck = -1; /* Default behaviour is just to warn */
-
-void __init acpi_check_s4_hw_signature(int check)
-{
-	sigcheck = check;
-}
+int acpi_check_s4_hw_signature = -1; /* Default behaviour is just to warn */
 
 static int acpi_hibernation_begin(pm_message_t stage)
 {
@@ -999,7 +994,7 @@ static void acpi_sleep_hibernate_setup(void)
 	hibernation_set_ops(old_suspend_ordering ?
 			&acpi_hibernation_ops_old : &acpi_hibernation_ops);
 	sleep_states[ACPI_STATE_S4] = 1;
-	if (!sigcheck)
+	if (!acpi_check_s4_hw_signature)
 		return;
 
 	acpi_get_table(ACPI_SIG_FACS, 1, (struct acpi_table_header **)&facs);
@@ -1011,7 +1006,7 @@ static void acpi_sleep_hibernate_setup(void)
 		 */
 		s4_hardware_signature = facs->hardware_signature;
 
-		if (sigcheck > 0) {
+		if (acpi_check_s4_hw_signature > 0) {
 			/*
 			 * If we're actually obeying the ACPI specification
 			 * then the signature is written out as part of the

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
@@ -526,7 +526,7 @@ acpi_status acpi_release_memory(acpi_handle handle, struct resource *res,
 int acpi_resources_are_enforced(void);
 
 #ifdef CONFIG_HIBERNATION
-void __init acpi_check_s4_hw_signature(int check);
+extern int acpi_check_s4_hw_signature;
 #endif
 
 #ifdef CONFIG_PM_SLEEP