powerpc/fsl: Add nospectre_v2 command line argument

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

BugLink: https://bugs.launchpad.net/bugs/1822870
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(backported from commit f633a8ad636efb5d4bba1a047d4a0f1ef719aa06)
Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 0c78fc08f11a7adb2cd9dcd13d6585405d3f4116..8d36456e1766797a8fbd4b73e2c67af248ccbc26 100644 (file)
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -65,6 +65,13 @@ 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
+void do_btb_flush_fixups(void);
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_SETUP_H */

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 1b395b85132be4c81a3740e7df6761f963df3d5e..4393a3834ec7fc4794cb464b6712a1a34520ea94 100644 (file)
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -26,6 +26,10 @@ 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)
 {
@@ -101,6 +105,23 @@ 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 */
+
 #ifdef CONFIG_PPC_BOOK3S_64
 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
 {