KVM: vmx/pmu: Fix dummy check if lbr_desc->event is created

mainline inclusion
from mainline-v5.12-rc1
commit 67b45af9
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4NP0K
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=67b45af946ec3148b64e6a3a1ee2ea8f79c5bc07

-------------------

If lbr_desc->event is successfully created, the intel_pmu_create_
guest_lbr_event() will return 0, otherwise it will return -ENOENT,
and then jump to LBR msrs dummy handling.

Fixes: 1b5ac322 ("KVM: vmx/pmu: Pass-through LBR msrs when the guest LBR event is ACTIVE")
Signed-off-by: NLike Xu <like.xu@linux.intel.com>
Message-Id: <20210223013958.1280444-1-like.xu@linux.intel.com>
[Add "< 0" and PTR_ERR to make the code clearer. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NWangJian <wangjian161@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/x86/kvm/vmx/pmu_intel.c

@@ -298,7 +298,7 @@ int intel_pmu_create_guest_lbr_event(struct kvm_vcpu *vcpu)
 	if (IS_ERR(event)) {
 		pr_debug_ratelimited("%s: failed %ld\n",
 					__func__, PTR_ERR(event));
-		return -ENOENT;
+		return PTR_ERR(event);
 	}
 	lbr_desc->event = event;
 	pmu->event_count++;
@@ -320,7 +320,7 @@ static bool intel_pmu_handle_lbr_msrs_access(struct kvm_vcpu *vcpu,
 	if (!intel_pmu_is_valid_lbr_msr(vcpu, index))
 		return false;
 
-	if (!lbr_desc->event && !intel_pmu_create_guest_lbr_event(vcpu))
+	if (!lbr_desc->event && intel_pmu_create_guest_lbr_event(vcpu) < 0)
 		goto dummy;
 
 	/*