linux-kernel - Re: [PATCH 12/27] x86/pkru: Provide .*_pkru

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Date:   Wed, 10 Apr 2019 18:52:41 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        kvm@...r.kernel.org, "Jason A. Donenfeld" <Jason@...c4.com>,
        Rik van Riel <riel@...riel.com>,
        Dave Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH 12/27] x86/pkru: Provide .*_pkru_ins() functions

On Wed, Apr 10, 2019 at 06:36:15PM +0200, Borislav Petkov wrote:
> Well, this is going in the wrong direction. The proper thing to do would
> be to have:
> 
> rdpkru()
> wrpkru()
> 
> which only do the inline asm with the respective opcodes. Just like
> rdtsc(), clflush(), etc.

IOW, like this:

---
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 2779ace16d23..e2948ce1376c 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -127,14 +127,14 @@ static inline int pte_dirty(pte_t pte)
 static inline u32 read_pkru(void)
 {
 	if (boot_cpu_has(X86_FEATURE_OSPKE))
-		return __read_pkru();
+		return rdpkru();
 	return 0;
 }
 
 static inline void write_pkru(u32 pkru)
 {
 	if (boot_cpu_has(X86_FEATURE_OSPKE))
-		__write_pkru(pkru);
+		wrpkru(pkru);
 }
 
 static inline int pte_young(pte_t pte)
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 43c029cdc3fe..396ff572d66a 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -92,7 +92,7 @@ static inline void native_write_cr8(unsigned long val)
 #endif
 
 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
-static inline u32 __read_pkru(void)
+static inline u32 rdpkru(void)
 {
 	u32 ecx = 0;
 	u32 edx, pkru;
@@ -107,7 +107,7 @@ static inline u32 __read_pkru(void)
 	return pkru;
 }
 
-static inline void __write_pkru(u32 pkru)
+static inline void wrpkru(u32 pkru)
 {
 	u32 ecx = 0, edx = 0;
 
@@ -119,12 +119,12 @@ static inline void __write_pkru(u32 pkru)
 		     : : "a" (pkru), "c"(ecx), "d"(edx));
 }
 #else
-static inline u32 __read_pkru(void)
+static inline u32 rdpkru(void)
 {
 	return 0;
 }
 
-static inline void __write_pkru(u32 pkru)
+static inline void wrpkru(u32 pkru)
 {
 }
 #endif
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index ab432a930ae8..85260aa2a920 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6413,7 +6413,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	if (static_cpu_has(X86_FEATURE_PKU) &&
 	    kvm_read_cr4_bits(vcpu, X86_CR4_PKE) &&
 	    vcpu->arch.pkru != vmx->host_pkru)
-		__write_pkru(vcpu->arch.pkru);
+		wrpkru(vcpu->arch.pkru);
 
 	pt_guest_enter(vmx);
 
@@ -6501,9 +6501,9 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	 */
 	if (static_cpu_has(X86_FEATURE_PKU) &&
 	    kvm_read_cr4_bits(vcpu, X86_CR4_PKE)) {
-		vcpu->arch.pkru = __read_pkru();
+		vcpu->arch.pkru = rdpkru();
 		if (vcpu->arch.pkru != vmx->host_pkru)
-			__write_pkru(vmx->host_pkru);
+			wrpkru(vmx->host_pkru);
 	}
 
 	vmx->nested.nested_run_pending = 0;

-- 
Regards/Gruss,
    Boris.

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