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Commit c847fe88 authored by Paolo Bonzini's avatar Paolo Bonzini
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KVM: x86: remove unnecessary memory barriers for shared MSRs 



There is no smp_rmb matching the smp_wmb.  shared_msr_update is called from
hardware_enable, which in turn is called via on_each_cpu.  on_each_cpu
and must imply a read memory barrier (on x86 the rmb is achieved simply
through asm volatile in native_apic_mem_write).

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d71ba788

arch/x86/kvm/x86.c

+1 −3
Original line number Diff line number Diff line
@@ -222,11 +222,9 @@ static void shared_msr_update(unsigned slot, u32 msr) 
void kvm_define_shared_msr(unsigned slot, u32 msr)

{

	BUG_ON(slot >= KVM_NR_SHARED_MSRS);

	shared_msrs_global.msrs[slot] = msr;

	if (slot >= shared_msrs_global.nr)

		shared_msrs_global.nr = slot + 1;

	shared_msrs_global.msrs[slot] = msr;

	/* we need ensured the shared_msr_global have been updated */

	smp_wmb();

}

EXPORT_SYMBOL_GPL(kvm_define_shared_msr);