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Message-Id: <20180118140152.955841165@infradead.org>
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Date: Thu, 18 Jan 2018 14:48:25 +0100
From: Peter Zijlstra <peterz@infradead.org>
From: Peter Zijlstra <peterz@infradead.org>
To: David Woodhouse <dwmw2@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-kernel@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>,
        Ashok Raj <ashok.raj@intel.com>, Tim Chen <tim.c.chen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Jun Nakajima <jun.nakajima@intel.com>,
        Asit Mallick <asit.k.mallick@intel.com>,
        Jason Baron <jbaron@akamai.com>, Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH 25/35] x86/speculation: Add inlines to control Indirect Branch Speculation
References: <20180118134800.711245485@infradead.org>
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Content-Disposition: inline; filename=x86-specctrl--Add-inlines-to-control-Indirect-Branch-Speculation.patch
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From: Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/nospec-branch.h |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -6,6 +6,7 @@
 #include <asm/alternative.h>
 #include <asm/alternative-asm.h>
 #include <asm/cpufeatures.h>
+#include <asm/msr.h>
 
 /*
  * Fill the CPU return stack buffer.
@@ -219,5 +220,16 @@ bool specctrl_force_enable_ibrs(void);
 bool specctrl_cond_enable_ibrs(bool full_retpoline);
 bool is_skylake_era(void);
 
+static inline void stop_indirect_branch_speculation(void)
+{
+	if (static_cpu_has(X86_FEATURE_IBRS))
+		native_wrmsrl(MSR_IA32_SPEC_CTRL, SPEC_CTRL_ENABLE_IBRS);
+}
+
+static inline void restart_indirect_branch_speculation(void)
+{
+	if (static_cpu_has(X86_FEATURE_IBRS))
+		native_wrmsrl(MSR_IA32_SPEC_CTRL, SPEC_CTRL_DISABLE_IBRS);
+}
 #endif /* __ASSEMBLY__ */
 #endif /* __NOSPEC_BRANCH_H__ */