linux-kernel - [tip:x86/asm] x86/paravirt: Make "unsafe" MSR accesses unsafe even if PARAVIRT=y

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Message-ID: <tip-4985ce15a397e9b6541548efe3b9ffac2dda9127@git.kernel.org>
Date:	Wed, 13 Apr 2016 04:46:05 -0700
From:	tip-bot for Andy Lutomirski <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	tglx@...utronix.de, pbonzini@...hat.com, bp@...en8.de,
	torvalds@...ux-foundation.org, luto@...nel.org,
	arjan@...ux.intel.com, hpa@...or.com, peterz@...radead.org,
	Xen-devel@...ts.xen.org, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, boris.ostrovsky@...cle.com,
	mingo@...nel.org, kvm@...r.kernel.org
Subject: [tip:x86/asm] x86/paravirt: Make "unsafe" MSR accesses unsafe even
 if PARAVIRT=y

Commit-ID:  4985ce15a397e9b6541548efe3b9ffac2dda9127
Gitweb:     http://git.kernel.org/tip/4985ce15a397e9b6541548efe3b9ffac2dda9127
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Sat, 2 Apr 2016 07:01:39 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 13 Apr 2016 11:37:46 +0200

x86/paravirt: Make "unsafe" MSR accesses unsafe even if PARAVIRT=y

Enabling CONFIG_PARAVIRT had an unintended side effect: rdmsr() turned
into rdmsr_safe() and wrmsr() turned into wrmsr_safe(), even on bare
metal.  Undo that by using the new unsafe paravirt MSR callbacks.

Tested-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Andy Lutomirski <luto@...nel.org>
Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: KVM list <kvm@...r.kernel.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: xen-devel <Xen-devel@...ts.xen.org>
Link: http://lkml.kernel.org/r/414fabd6d3527703077c6c2a797223d0a9c3b081.1459605520.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/paravirt.h | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 97839fa..3c73141 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -152,24 +152,21 @@ static inline int paravirt_write_msr_safe(unsigned msr,
 	return PVOP_CALL3(int, pv_cpu_ops.write_msr_safe, msr, low, high);
 }
 
-/* These should all do BUG_ON(_err), but our headers are too tangled. */
 #define rdmsr(msr, val1, val2)			\
 do {						\
-	int _err;				\
-	u64 _l = paravirt_read_msr_safe(msr, &_err);	\
+	u64 _l = paravirt_read_msr(msr);	\
 	val1 = (u32)_l;				\
 	val2 = _l >> 32;			\
 } while (0)
 
 #define wrmsr(msr, val1, val2)			\
 do {						\
-	paravirt_write_msr_safe(msr, val1, val2);	\
+	paravirt_write_msr(msr, val1, val2);	\
 } while (0)
 
 #define rdmsrl(msr, val)			\
 do {						\
-	int _err;				\
-	val = paravirt_read_msr_safe(msr, &_err);	\
+	val = paravirt_read_msr(msr);		\
 } while (0)
 
 static inline void wrmsrl(unsigned msr, u64 val)