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2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/arch/x86/include/asm/acenv.h
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@@ -1,12 +1,9 @@
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+/* SPDX-License-Identifier: GPL-2.0-only */
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 /*
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  * X86 specific ACPICA environments and implementation
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  *
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  * Copyright (C) 2014, Intel Corporation
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  *   Author: Lv Zheng <lv.zheng@intel.com>
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- *
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- * This program is free software; you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License version 2 as
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- * published by the Free Software Foundation.
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  */
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 #ifndef _ASM_X86_ACENV_H
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@@ -16,7 +13,19 @@
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 /* Asm macros */
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-#define ACPI_FLUSH_CPU_CACHE()	wbinvd()
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+/*
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+ * ACPI_FLUSH_CPU_CACHE() flushes caches on entering sleep states.
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+ * It is required to prevent data loss.
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+ *
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+ * While running inside virtual machine, the kernel can bypass cache flushing.
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+ * Changing sleep state in a virtual machine doesn't affect the host system
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+ * sleep state and cannot lead to data loss.
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+ */
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+#define ACPI_FLUSH_CPU_CACHE()					\
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+do {								\
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+	if (!cpu_feature_enabled(X86_FEATURE_HYPERVISOR))	\
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+		wbinvd();					\
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+} while (0)
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 int __acpi_acquire_global_lock(unsigned int *lock);
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 int __acpi_release_global_lock(unsigned int *lock);