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

[tip-bot for Andy Lutomirski <tipbot@xxxxxxxxx>]

Commit-ID:  4985ce15a397e9b6541548efe3b9ffac2dda9127
Gitweb:     http://git.kernel.org/tip/4985ce15a397e9b6541548efe3b9ffac2dda9127
Author:     Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Sat, 2 Apr 2016 07:01:39 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: KVM list <kvm@xxxxxxxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: xen-devel <Xen-devel@xxxxxxxxxxxxx>
Link: 
http://lkml.kernel.org/r/414fabd6d3527703077c6c2a797223d0a9c3b081.1459605520.git.luto@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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)

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