[tip: x86/fpu] x86/pkru: Provide pkru_write_default()

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the x86/fpu branch of tip:

Commit-ID:     ff7ebff47c595e747aa1bb10d8a30b2acb7d425b
Gitweb:        https://git.kernel.org/tip/ff7ebff47c595e747aa1bb10d8a30b2acb7d425b
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Wed, 23 Jun 2021 14:02:09 +02:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 23 Jun 2021 19:09:53 +02:00

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 task's xsave buffer.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20210623121455.513729794@xxxxxxxxxxxxx
---
 arch/x86/include/asm/pkru.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/include/asm/pkru.h b/arch/x86/include/asm/pkru.h
index 19d3d7b..7e45509 100644
--- 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