[PATCH v4 17/21] KVM: x86/pmu: Factor out fixed counter control bit calculation
From: Zide Chen
Date: Thu Nov 12 2026 - 16:36:39 EST
Rename intel_pmu_enable_fixed_counter_bits() to
intel_pmu_fixed_ctrl_bits() and have it return the computed fixed
counter control mask instead of updating fixed_ctr_ctrl_rsvd directly.
Accumulate the desired fixed counter control bits during PMU setup and
apply them once in intel_pmu_refresh().
Move the helper earlier in the file so it can also be reused for
upcoming ANYTHREAD_DEPRECATION emulation.
No functional change intended.
Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
Reviewed-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
v4:
- Pass 'pmu' directly to kvm_for_each_fixed_counter().
---
arch/x86/kvm/vmx/pmu_intel.c | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index d259b66abac8..65b6f274a8f6 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -55,6 +55,17 @@ static struct x86_pmu_lbr *vcpu_to_lbr_records(struct kvm_vcpu *vcpu)
#pragma GCC poison to_vmx
+static u64 intel_pmu_fixed_ctrl_bits(struct kvm_pmu *pmu, u64 bits)
+{
+ u64 fixed_ctrl_bits = 0;
+ int i;
+
+ kvm_for_each_fixed_counter(i, pmu)
+ fixed_ctrl_bits |= intel_fixed_bits_by_idx(i, bits);
+
+ return fixed_ctrl_bits;
+}
+
static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data)
{
/*
@@ -534,20 +545,13 @@ static __always_inline u64 intel_get_fixed_pmc_eventsel(unsigned int index)
return eventsel;
}
-static void intel_pmu_enable_fixed_counter_bits(struct kvm_pmu *pmu, u64 bits)
-{
- int i;
-
- kvm_for_each_fixed_counter(i, pmu)
- pmu->fixed_ctr_ctrl_rsvd &= ~intel_fixed_bits_by_idx(i, bits);
-}
-
static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu);
int nr_gp_counters, nr_fixed_counters;
struct kvm_cpuid_entry2 *entry;
+ u64 fixed_enable_bits = 0;
union cpuid10_eax eax;
union cpuid10_edx edx;
u64 perf_capabilities;
@@ -633,9 +637,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
kvm_pmu_cap.bit_width_fixed);
pmu->counter_bitmask[KVM_PMC_FIXED] = BIT_ULL(edx.split.bit_width_fixed) - 1;
- intel_pmu_enable_fixed_counter_bits(pmu, INTEL_FIXED_0_KERNEL |
- INTEL_FIXED_0_USER |
- INTEL_FIXED_0_ENABLE_PMI);
+ fixed_enable_bits |= INTEL_FIXED_0_KERNEL | INTEL_FIXED_0_USER |
+ INTEL_FIXED_0_ENABLE_PMI;
counter_rsvd = ~(kvm_gp_pmc_mask(pmu) |
(kvm_fixed_pmc_mask(pmu) << KVM_FIXED_PMC_BASE_IDX));
@@ -651,11 +654,14 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
pmu->pebs_enable_rsvd = counter_rsvd;
pmu->eventsel_rsvd &= ~ICL_EVENTSEL_ADAPTIVE;
pmu->pebs_data_cfg_rsvd = ~0xff00000full;
- intel_pmu_enable_fixed_counter_bits(pmu, ICL_FIXED_0_ADAPTIVE);
+ fixed_enable_bits |= ICL_FIXED_0_ADAPTIVE;
} else {
pmu->pebs_enable_rsvd = ~kvm_gp_pmc_mask(pmu);
}
}
+
+ pmu->fixed_ctr_ctrl_rsvd &=
+ ~intel_pmu_fixed_ctrl_bits(pmu, fixed_enable_bits);
}
static void intel_pmu_init(struct kvm_vcpu *vcpu)
--
2.56.1