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x86/paravirt: Add paravirt_{read,write}_msr()

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This adds paravirt callbacks for unsafe MSR access.  On native, they
call native_{read,write}_msr().  On Xen, they use xen_{read,write}_msr_safe().

Nothing uses them yet for ease of bisection.  The next patch will
use them in rdmsrl(), wrmsrl(), etc.

I intentionally didn't make them warn on #GP on Xen.  I think that
should be done separately by the Xen maintainers.

Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: KVM list <kvm@vger.kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel <Xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/880eebc5dcd2ad9f310d41345f82061ea500e9fa.1459605520.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski
2016-04-02 07:01:38 -07:00
committed by Ingo Molnar
parent fbd704374d
commit dd2f4a004b
5 changed files with 47 additions and 4 deletions
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5
arch/x86/include/asm/msr.h
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@@ -111,8 +111,9 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr,
return EAX_EDX_VAL(val, low, high);
}
static inline void native_write_msr(unsigned int msr,
unsigned low, unsigned high)
/* Can be uninlined because referenced by paravirt */
notrace static inline void native_write_msr(unsigned int msr,
unsigned low, unsigned high)
{
asm volatile("1: wrmsr\n"
"2:\n"