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Subject[PATCH v2 6/8] x86/microcode: Recheck IBRS features on microcode reload
Date
On new microcode write, check whether IBRS
is present by rescanning IBRS feature.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
arch/x86/include/asm/spec_ctrl.h | 1 +
arch/x86/kernel/cpu/microcode/core.c | 4 ++++
arch/x86/kernel/cpu/spec_ctrl.c | 18 ++++++++++--------
3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/spec_ctrl.h b/arch/x86/include/asm/spec_ctrl.h
index 62c5dc8..be08ae7 100644
--- a/arch/x86/include/asm/spec_ctrl.h
+++ b/arch/x86/include/asm/spec_ctrl.h
@@ -8,6 +8,7 @@
#include <asm/microcode.h>

void scan_spec_ctrl_feature(struct cpuinfo_x86 *c);
+void rescan_spec_ctrl_feature(struct cpuinfo_x86 *c);
bool ibrs_inuse(void);

extern unsigned int dynamic_ibrs;
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index c4fa4a8..848c3e9 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -40,6 +40,7 @@
#include <asm/processor.h>
#include <asm/cmdline.h>
#include <asm/setup.h>
+#include <asm/spec_ctrl.h>

#define DRIVER_VERSION "2.2"

@@ -444,6 +445,9 @@ static ssize_t microcode_write(struct file *file, const char __user *buf,
if (ret > 0)
perf_check_microcode();

+ /* check spec_ctrl capabilities */
+ rescan_spec_ctrl_feature(&boot_cpu_data);
+
mutex_unlock(&microcode_mutex);
put_online_cpus();

diff --git a/arch/x86/kernel/cpu/spec_ctrl.c b/arch/x86/kernel/cpu/spec_ctrl.c
index 1641bec..28107a2 100644
--- a/arch/x86/kernel/cpu/spec_ctrl.c
+++ b/arch/x86/kernel/cpu/spec_ctrl.c
@@ -24,13 +24,18 @@ static bool ibrs_admin_disabled;
/* mutex to serialize IBRS control changes */
DEFINE_MUTEX(spec_ctrl_mutex);

+static inline void set_ibrs_feature(void)
+{
+ if (!ibrs_admin_disabled) {
+ dynamic_ibrs = 1;
+ ibrs_enabled = IBRS_ENABLED;
+ }
+}
+
void scan_spec_ctrl_feature(struct cpuinfo_x86 *c)
{
if ((!c->cpu_index) && (boot_cpu_has(X86_FEATURE_SPEC_CTRL))) {
- if (!ibrs_admin_disabled) {
- dynamic_ibrs = 1;
- ibrs_enabled = IBRS_ENABLED;
- }
+ set_ibrs_feature();
}
}
EXPORT_SYMBOL_GPL(scan_spec_ctrl_feature);
@@ -43,10 +48,7 @@ void rescan_spec_ctrl_feature(struct cpuinfo_x86 *c)
{
mutex_lock(&spec_ctrl_mutex);
if (boot_cpu_has(X86_FEATURE_SPEC_CTRL)) {
- if (!ibrs_admin_disabled) {
- dynamic_ibrs = 1;
- ibrs_enabled = IBRS_ENABLED;
- }
+ set_ibrs_feature();
}
mutex_unlock(&spec_ctrl_mutex);
}
--
2.9.4
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