x86: pkey: introduce write_pkru() for KVM

KVM will use it to switch pkru between guest and host. CC: Ingo Molnar <mingo@redhat.com> CC: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com> Signed-off-by: Huaitong Han <huaitong.han@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
mariux64 · Mar 22, 2016 · 9e90199 · 9e90199
1 parent 17a511f
commit 9e90199
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diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
@@ -107,6 +107,12 @@ static inline u32 read_pkru(void)
 	return 0;
 }
 
+static inline void write_pkru(u32 pkru)
+{
+	if (boot_cpu_has(X86_FEATURE_OSPKE))
+		__write_pkru(pkru);
+}
+
 static inline int pte_young(pte_t pte)
 {
 	return pte_flags(pte) & _PAGE_ACCESSED;

diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
@@ -113,11 +113,27 @@ static inline u32 __read_pkru(void)
 		     : "c" (ecx));
 	return pkru;
 }
+
+static inline void __write_pkru(u32 pkru)
+{
+	u32 ecx = 0, edx = 0;
+
+	/*
+	 * "wrpkru" instruction.  Loads contents in EAX to PKRU,
+	 * requires that ecx = edx = 0.
+	 */
+	asm volatile(".byte 0x0f,0x01,0xef\n\t"
+		     : : "a" (pkru), "c"(ecx), "d"(edx));
+}
 #else
 static inline u32 __read_pkru(void)
 {
 	return 0;
 }
+
+static inline void __write_pkru(u32 pkru)
+{
+}
 #endif
 
 static inline void native_wbinvd(void)