KVM: x86/vPMU: Fix unnecessary signed extension for AMD PERFCTRn

According to AMD programmer's manual, AMD PERFCTRn is 64-bit MSR which,
unlike Intel perf counters, doesn't require signed extension. This
patch removes the unnecessary conversion in SVM vPMU code when PERFCTRn
is being updated.
Signed-off-by: Wei Huang <wei@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/pmu_amd.c

@@ -133,8 +133,6 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	/* MSR_K7_PERFCTRn */
 	pmc = get_gp_pmc(pmu, msr, MSR_K7_PERFCTR0);
 	if (pmc) {
-		if (!msr_info->host_initiated)
-			data = (s64)data;
 		pmc->counter += data - pmc_read_counter(pmc);
 		return 0;
 	}