[Devel] [PATCH RHEL8 COMMIT] KVM: x86/vPMU: handle access to LBR stack regardless of PMU counters presence

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.45
------>
commit de2b440a9eb93616aa651214295645d24dc55f69
Author: Jan Dakinevich <jan.dakinevich at virtuozzo.com>
Date:   Fri Jun 18 15:13:51 2021 +0300

    KVM: x86/vPMU: handle access to LBR stack regardless of PMU counters presence
    
    Previously if no PMU counters were exposed to guest, KVM skipped whole
    remaining PMU-related initialisation, including filling of LBR-related
    information. It is wrong, since LBR support doesn't depend on
    existence of PMU counters.
    
    https://jira.sw.ru/browse/PSBM-94429
    Signed-off-by: Jan Dakinevich <jan.dakinevich at virtuozzo.com>
    
    https://jira.sw.ru/browse/PSBM-127846
    (cherry-picked from vz7 commit dc33198816f4 ("KVM: x86/vPMU: handle
    access to LBR stack regardless of PMU counters presence"))
    
    Fixes: 1fb36a7c3b57 ("KVM: x86/vPMU: Ignore access to LBR-related MSRs")
    Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 arch/x86/kvm/vmx/pmu_intel.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 0df709f5b856..ccfe7ce4b78f 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -333,6 +333,11 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
 	pmu->version = 0;
 	pmu->reserved_bits = 0xffffffff00200000ull;
 
+	entry = kvm_find_cpuid_entry(vcpu, 1, 0);
+	if (entry)
+		intel_pmu_lbr_fill(&pmu->lbr,
+			x86_family(entry->eax), x86_model(entry->eax));
+
 	entry = kvm_find_cpuid_entry(vcpu, 0xa, 0);
 	if (!entry)
 		return;
@@ -383,11 +388,6 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
 		INTEL_PMC_MAX_GENERIC, pmu->nr_arch_fixed_counters);
 
 	nested_vmx_pmu_entry_exit_ctls_update(vcpu);
-
-	entry = kvm_find_cpuid_entry(vcpu, 1, 0);
-	if (entry)
-		intel_pmu_lbr_fill(&pmu->lbr,
-			x86_family(entry->eax), x86_model(entry->eax));
 }
 
 static void intel_pmu_init(struct kvm_vcpu *vcpu)