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KVM: x86/pmu: Disable RDPMC interception for compatible mediated vPMU

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Disable RDPMC interception for vCPUs with a mediated vPMU that is
compatible with the host PMU, i.e. that doesn't require KVM emulation of
RDPMC to honor the guest's vCPU model.  With a mediated vPMU, all guest
state accessible via RDPMC is loaded into hardware while the guest is
running.

Adust RDPMC interception only for non-TDX guests, as the TDX module is
responsible for managing RDPMC intercepts based on the TD configuration.

Co-developed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Co-developed-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Xudong Hao <xudong.hao@intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Tested-by: Manali Shukla <manali.shukla@amd.com>
Link: https://patch.msgid.link/20251206001720.468579-21-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Dapeng Mi 2025-12-05 16:16:56 -08:00 committed by Sean Christopherson
parent 1c4ba7286a
commit 8062427212
5 changed files with 40 additions and 0 deletions
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26
arch/x86/kvm/pmu.c
View File

@ -714,6 +714,32 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
return 0;
}
bool kvm_need_rdpmc_intercept(struct kvm_vcpu *vcpu)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
if (!kvm_vcpu_has_mediated_pmu(vcpu))
return true;
/*
* VMware allows access to these Pseduo-PMCs even when read via RDPMC
* in Ring3 when CR4.PCE=0.
*/
if (enable_vmware_backdoor)
return true;
/*
* Note! Check *host* PMU capabilities, not KVM's PMU capabilities, as
* KVM's capabilities are constrained based on KVM support, i.e. KVM's
* capabilities themselves may be a subset of hardware capabilities.
*/
return pmu->nr_arch_gp_counters != kvm_host_pmu.num_counters_gp ||
pmu->nr_arch_fixed_counters != kvm_host_pmu.num_counters_fixed ||
pmu->counter_bitmask[KVM_PMC_GP] != (BIT_ULL(kvm_host_pmu.bit_width_gp) - 1) ||
pmu->counter_bitmask[KVM_PMC_FIXED] != (BIT_ULL(kvm_host_pmu.bit_width_fixed) - 1);
}
EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_need_rdpmc_intercept);
void kvm_pmu_deliver_pmi(struct kvm_vcpu *vcpu)
{
if (lapic_in_kernel(vcpu)) {

1
arch/x86/kvm/pmu.h
View File

@ -238,6 +238,7 @@ void kvm_pmu_instruction_retired(struct kvm_vcpu *vcpu);
void kvm_pmu_branch_retired(struct kvm_vcpu *vcpu);
bool is_vmware_backdoor_pmc(u32 pmc_idx);
bool kvm_need_rdpmc_intercept(struct kvm_vcpu *vcpu);
extern struct kvm_pmu_ops intel_pmu_ops;
extern struct kvm_pmu_ops amd_pmu_ops;

5
arch/x86/kvm/svm/svm.c
View File

@ -1011,6 +1011,11 @@ static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu)
svm->vmcb->control.virt_ext |= VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK;
}
}
if (kvm_need_rdpmc_intercept(vcpu))
svm_set_intercept(svm, INTERCEPT_RDPMC);
else
svm_clr_intercept(svm, INTERCEPT_RDPMC);
}
static void svm_recalc_intercepts(struct kvm_vcpu *vcpu)

7
arch/x86/kvm/vmx/vmx.c
View File

@ -4300,8 +4300,15 @@ static void vmx_recalc_msr_intercepts(struct kvm_vcpu *vcpu)
*/
}
static void vmx_recalc_instruction_intercepts(struct kvm_vcpu *vcpu)
{
exec_controls_changebit(to_vmx(vcpu), CPU_BASED_RDPMC_EXITING,
kvm_need_rdpmc_intercept(vcpu));
}
void vmx_recalc_intercepts(struct kvm_vcpu *vcpu)
{
vmx_recalc_instruction_intercepts(vcpu);
vmx_recalc_msr_intercepts(vcpu);
}

1
arch/x86/kvm/x86.c
View File

@ -3945,6 +3945,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
vcpu->arch.perf_capabilities = data;
kvm_pmu_refresh(vcpu);
kvm_make_request(KVM_REQ_RECALC_INTERCEPTS, vcpu);
break;
case MSR_IA32_PRED_CMD: {
u64 reserved_bits = ~(PRED_CMD_IBPB | PRED_CMD_SBPB);