Add a new __update_spec_ctrl() helper which is a variant of
update_spec_ctrl() that can be used in a noinstr function.
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
arch/x86/include/asm/nospec-branch.h | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 55388c9f7601..1d363fcea207 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -9,7 +9,7 @@
#include <asm/alternative.h>
#include <asm/cpufeatures.h>
-#include <asm/msr-index.h>
+#include <asm/msr.h>
#include <asm/unwind_hints.h>
#include <asm/percpu.h>
#include <asm/current.h>
@@ -488,6 +488,15 @@ DECLARE_PER_CPU(u64, x86_spec_ctrl_current);
extern void update_spec_ctrl_cond(u64 val);
extern u64 spec_ctrl_current(void);
+/*
+ * This can be used in noinstr function.
+ */
+static __always_inline void __update_spec_ctrl(u64 val)
+{
+ __this_cpu_write(x86_spec_ctrl_current, val);
+ native_wrmsrl(MSR_IA32_SPEC_CTRL, val);
+}
+
/*
* With retpoline, we must use IBRS to restrict branch prediction
* before calling into firmware.
--
2.31.1
