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: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c675ea33..2d62229 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -222,11 +222,9 @@
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);