From 8b6ab2e2cfa9fd11db5c9a95b0d4dff1b16dfdeb Mon Sep 17 00:00:00 2001
From: Diana Craciun <diana.craciun@nxp.com>
Date: Wed, 12 Dec 2018 16:03:04 +0200
Subject: [PATCH] powerpc/fsl: Add nospectre_v2 command line argument

References: bsc#1131107
Patch-mainline: v5.0-rc1
Git-commit: f633a8ad636efb5d4bba1a047d4a0f1ef719aa06

When the command line argument is present, the Spectre variant 2
mitigations are disabled.

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/include/asm/setup.h |  6 ++++++
 arch/powerpc/kernel/security.c   | 21 +++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 84ae150ce6a6..4cc73d5ad2af 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -61,6 +61,12 @@ void do_barrier_nospec_fixups_range(bool enable, void *start, void *end);
 static inline void do_barrier_nospec_fixups_range(bool enable, void *start, void *end) { };
 #endif
 
+#ifdef CONFIG_PPC_FSL_BOOK3E
+void setup_spectre_v2(void);
+#else
+static inline void setup_spectre_v2(void) {};
+#endif
+
 #endif /* !__ASSEMBLY__ */
 
 #endif	/* _ASM_POWERPC_SETUP_H */
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index bcb3a4971f90..b03357d76cd2 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -28,6 +28,10 @@ static enum count_cache_flush_type count_cache_flush_type = COUNT_CACHE_FLUSH_NO
 
 bool barrier_nospec_enabled;
 static bool no_nospec;
+static bool btb_flush_enabled;
+#ifdef CONFIG_PPC_FSL_BOOK3E
+static bool no_spectrev2;
+#endif
 
 static void enable_barrier_nospec(bool enable)
 {
@@ -103,6 +107,23 @@ static __init int barrier_nospec_debugfs_init(void)
 device_initcall(barrier_nospec_debugfs_init);
 #endif /* CONFIG_DEBUG_FS */
 
+#ifdef CONFIG_PPC_FSL_BOOK3E
+static int __init handle_nospectre_v2(char *p)
+{
+	no_spectrev2 = true;
+
+	return 0;
+}
+early_param("nospectre_v2", handle_nospectre_v2);
+void setup_spectre_v2(void)
+{
+	if (no_spectrev2)
+		do_btb_flush_fixups();
+	else
+		btb_flush_enabled = true;
+}
+#endif /* CONFIG_PPC_FSL_BOOK3E */
+
 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	bool thread_priv;
-- 
2.22.0