Commit d8f0e0b0 authored by Christopher M. Riedl's avatar Christopher M. Riedl Committed by Michael Ellerman

powerpc/64s: support nospectre_v2 cmdline option

Add support for disabling the kernel implemented spectre v2 mitigation
(count cache flush on context switch) via the nospectre_v2 and
mitigations=off cmdline options.
Suggested-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarChristopher M. Riedl <cmr@informatik.wtf>
Reviewed-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190524024647.381-1-cmr@informatik.wtf
parent 6652bf64
......@@ -28,7 +28,7 @@ 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
#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64)
static bool no_spectrev2;
#endif
......@@ -114,7 +114,7 @@ static __init int security_feature_debugfs_init(void)
device_initcall(security_feature_debugfs_init);
#endif /* CONFIG_DEBUG_FS */
#ifdef CONFIG_PPC_FSL_BOOK3E
#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64)
static int __init handle_nospectre_v2(char *p)
{
no_spectrev2 = true;
......@@ -122,6 +122,9 @@ static int __init handle_nospectre_v2(char *p)
return 0;
}
early_param("nospectre_v2", handle_nospectre_v2);
#endif /* CONFIG_PPC_FSL_BOOK3E || CONFIG_PPC_BOOK3S_64 */
#ifdef CONFIG_PPC_FSL_BOOK3E
void setup_spectre_v2(void)
{
if (no_spectrev2 || cpu_mitigations_off())
......@@ -399,7 +402,17 @@ static void toggle_count_cache_flush(bool enable)
void setup_count_cache_flush(void)
{
toggle_count_cache_flush(true);
bool enable = true;
if (no_spectrev2 || cpu_mitigations_off()) {
if (security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED) ||
security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED))
pr_warn("Spectre v2 mitigations not under software control, can't disable\n");
enable = false;
}
toggle_count_cache_flush(enable);
}
#ifdef CONFIG_DEBUG_FS
......
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