This is a note to let you know that I've just added the patch titled
KVM: x86/pmu: Reset the PMU, i.e. stop counters, before refreshing
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-pmu-reset-the-pmu-i.e.-stop-counters-before-refreshing.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1647b52757d59131fe30cf73fa36fac834d4367f Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Fri, 3 Nov 2023 16:05:37 -0700
Subject: KVM: x86/pmu: Reset the PMU, i.e. stop counters, before refreshing
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 1647b52757d59131fe30cf73fa36fac834d4367f upstream.
Stop all counters and release all perf events before refreshing the vPMU,
i.e. before reconfiguring the vPMU to respond to changes in the vCPU
model.
Clear need_cleanup in kvm_pmu_reset() as well so that KVM doesn't
prematurely stop counters, e.g. if KVM enters the guest and enables
counters before the vCPU is scheduled out.
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231103230541.352265-3-seanjc@xxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/pmu.c | 35 ++++++++++++++++++++++-------------
1 file changed, 22 insertions(+), 13 deletions(-)
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -657,25 +657,14 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcp
return 0;
}
-/* refresh PMU settings. This function generally is called when underlying
- * settings are changed (such as changes of PMU CPUID by guest VMs), which
- * should rarely happen.
- */
-void kvm_pmu_refresh(struct kvm_vcpu *vcpu)
-{
- if (KVM_BUG_ON(kvm_vcpu_has_run(vcpu), vcpu->kvm))
- return;
-
- bitmap_zero(vcpu_to_pmu(vcpu)->all_valid_pmc_idx, X86_PMC_IDX_MAX);
- static_call(kvm_x86_pmu_refresh)(vcpu);
-}
-
void kvm_pmu_reset(struct kvm_vcpu *vcpu)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
struct kvm_pmc *pmc;
int i;
+ pmu->need_cleanup = false;
+
bitmap_zero(pmu->reprogram_pmi, X86_PMC_IDX_MAX);
for_each_set_bit(i, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX) {
@@ -695,6 +684,26 @@ void kvm_pmu_reset(struct kvm_vcpu *vcpu
static_call_cond(kvm_x86_pmu_reset)(vcpu);
}
+
+/*
+ * Refresh the PMU configuration for the vCPU, e.g. if userspace changes CPUID
+ * and/or PERF_CAPABILITIES.
+ */
+void kvm_pmu_refresh(struct kvm_vcpu *vcpu)
+{
+ if (KVM_BUG_ON(kvm_vcpu_has_run(vcpu), vcpu->kvm))
+ return;
+
+ /*
+ * Stop/release all existing counters/events before realizing the new
+ * vPMU model.
+ */
+ kvm_pmu_reset(vcpu);
+
+ bitmap_zero(vcpu_to_pmu(vcpu)->all_valid_pmc_idx, X86_PMC_IDX_MAX);
+ static_call(kvm_x86_pmu_refresh)(vcpu);
+}
+
void kvm_pmu_init(struct kvm_vcpu *vcpu)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-6.6/kvm-x86-pmu-reset-the-pmu-i.e.-stop-counters-before-refreshing.patch
queue-6.6/kvm-x86-pmu-move-pmu-reset-logic-to-common-x86-code.patch
queue-6.6/x86-kvm-do-not-try-to-disable-kvmclock-if-it-was-not-enabled.patch
queue-6.6/revert-nsvm-check-for-reserved-encodings-of-tlb_control-in-nested-vmcb.patch
