linux-kernel - [patch V2 37/52] x86/pkru: Provide pkru_write

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Date:   Mon, 14 Jun 2021 17:44:45 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [patch V2 37/52] x86/pkru: Provide pkru_write_default()

Provide a simple and trivial helper which just writes the PKRU default
value without trying to fiddle with the tasks xsave buffer.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/include/asm/pkru.h |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/arch/x86/include/asm/pkru.h
+++ b/arch/x86/include/asm/pkru.h
@@ -60,4 +60,12 @@ static inline void write_pkru(u32 pkru)
 	fpregs_unlock();
 }
 
+static inline void pkru_write_default(void)
+{
+	if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
+		return;
+
+	wrpkru(pkru_get_init_value());
+}
+
 #endif