Commit 8bca8c5c authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: VMX: Refactor intel_pmu_{g,}set_msr() to align with other helpers 

Invert the flows in intel_pmu_{g,s}et_msr()'s case statements so that
they follow the kernel's preferred style of:

        if (<not valid>)
                return <error>

        <commit change>
        return <success>

which is also the style used by every other {g,s}et_msr() helper (except
AMD's PMU variant, which doesn't use a switch statement).

Modify the "set" paths with costly side effects, i.e. that reprogram
counters, to skip only the side effects, i.e. to perform reserved bits
checks even if the value is unchanged.  None of the reserved bits checks
are expensive, so there's no strong justification for skipping them, and
guarding only the side effect makes it slightly more obvious what is being
skipped and why.

No functional change intended (assuming no reserved bit bugs).

Link: https://lkml.kernel.org/r/Y%2B6cfen%2FCpO3%2FdLO%40google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent cdd2fbf6

arch/x86/kvm/vmx/pmu_intel.c

+57 −52
Original line number Diff line number Diff line
@@ -351,47 +351,49 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
	switch (msr) {

	case MSR_CORE_PERF_FIXED_CTR_CTRL:

		msr_info->data = pmu->fixed_ctr_ctrl;

		return 0;

		break;

	case MSR_CORE_PERF_GLOBAL_STATUS:

		msr_info->data = pmu->global_status;

		return 0;

		break;

	case MSR_CORE_PERF_GLOBAL_CTRL:

		msr_info->data = pmu->global_ctrl;

		return 0;

		break;

	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:

		msr_info->data = 0;

		return 0;

		break;

	case MSR_IA32_PEBS_ENABLE:

		msr_info->data = pmu->pebs_enable;

		return 0;

		break;

	case MSR_IA32_DS_AREA:

		msr_info->data = pmu->ds_area;

		return 0;

		break;

	case MSR_PEBS_DATA_CFG:

		msr_info->data = pmu->pebs_data_cfg;

		return 0;

		break;

	default:

		if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||

		    (pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {

			u64 val = pmc_read_counter(pmc);

			msr_info->data =

				val & pmu->counter_bitmask[KVM_PMC_GP];

			return 0;

			break;

		} else if ((pmc = get_fixed_pmc(pmu, msr))) {

			u64 val = pmc_read_counter(pmc);

			msr_info->data =

				val & pmu->counter_bitmask[KVM_PMC_FIXED];

			return 0;

			break;

		} else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) {

			msr_info->data = pmc->eventsel;

			return 0;

		} else if (intel_pmu_handle_lbr_msrs_access(vcpu, msr_info, true))

			return 0;

			break;

		} else if (intel_pmu_handle_lbr_msrs_access(vcpu, msr_info, true)) {

			break;

		}



		return 1;

	}



	return 0;

}



static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)

{

	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
@@ -402,44 +404,43 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 


	switch (msr) {

	case MSR_CORE_PERF_FIXED_CTR_CTRL:

		if (pmu->fixed_ctr_ctrl == data)

			return 0;

		if (!(data & pmu->fixed_ctr_ctrl_mask)) {

		if (data & pmu->fixed_ctr_ctrl_mask)

			return 1;



		if (pmu->fixed_ctr_ctrl != data)

			reprogram_fixed_counters(pmu, data);

			return 0;

		}

		break;

	case MSR_CORE_PERF_GLOBAL_STATUS:

		if (msr_info->host_initiated) {

		if (!msr_info->host_initiated)

			return 1; /* RO MSR */



		pmu->global_status = data;

			return 0;

		}

		break; /* RO MSR */

		break;

	case MSR_CORE_PERF_GLOBAL_CTRL:

		if (pmu->global_ctrl == data)

			return 0;

		if (kvm_valid_perf_global_ctrl(pmu, data)) {

		if (!kvm_valid_perf_global_ctrl(pmu, data))

			return 1;



		if (pmu->global_ctrl != data) {

			diff = pmu->global_ctrl ^ data;

			pmu->global_ctrl = data;

			reprogram_counters(pmu, diff);

			return 0;

		}

		break;

	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:

		if (!(data & pmu->global_ovf_ctrl_mask)) {

		if (data & pmu->global_ovf_ctrl_mask)

			return 1;



		if (!msr_info->host_initiated)

			pmu->global_status &= ~data;

			return 0;

		}

		break;

	case MSR_IA32_PEBS_ENABLE:

		if (pmu->pebs_enable == data)

			return 0;

		if (!(data & pmu->pebs_enable_mask)) {

		if (data & pmu->pebs_enable_mask)

			return 1;



		if (pmu->pebs_enable != data) {

			diff = pmu->pebs_enable ^ data;

			pmu->pebs_enable = data;

			reprogram_counters(pmu, diff);

			return 0;

		}

		break;

	case MSR_IA32_DS_AREA:
@@ -447,15 +448,14 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
			return 1;

		if (is_noncanonical_address(data, vcpu))

			return 1;



		pmu->ds_area = data;

		return 0;

		break;

	case MSR_PEBS_DATA_CFG:

		if (pmu->pebs_data_cfg == data)

			return 0;

		if (!(data & pmu->pebs_data_cfg_mask)) {

		if (data & pmu->pebs_data_cfg_mask)

			return 1;



		pmu->pebs_data_cfg = data;

			return 0;

		}

		break;

	default:

		if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
@@ -463,35 +463,40 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
			if ((msr & MSR_PMC_FULL_WIDTH_BIT) &&

			    (data & ~pmu->counter_bitmask[KVM_PMC_GP]))

				return 1;



			if (!msr_info->host_initiated &&

			    !(msr & MSR_PMC_FULL_WIDTH_BIT))

				data = (s64)(s32)data;

			pmc->counter += data - pmc_read_counter(pmc);

			pmc_update_sample_period(pmc);

			return 0;

			break;

		} else if ((pmc = get_fixed_pmc(pmu, msr))) {

			pmc->counter += data - pmc_read_counter(pmc);

			pmc_update_sample_period(pmc);

			return 0;

			break;

		} else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) {

			if (data == pmc->eventsel)

				return 0;

			reserved_bits = pmu->reserved_bits;

			if ((pmc->idx == 2) &&

			    (pmu->raw_event_mask & HSW_IN_TX_CHECKPOINTED))

				reserved_bits ^= HSW_IN_TX_CHECKPOINTED;

			if (!(data & reserved_bits)) {

			if (data & reserved_bits)

				return 1;



			if (data != pmc->eventsel) {

				pmc->eventsel = data;

				kvm_pmu_request_counter_reprogam(pmc);

				return 0;

			}

		} else if (intel_pmu_handle_lbr_msrs_access(vcpu, msr_info, false))

			return 0;

			break;

		} else if (intel_pmu_handle_lbr_msrs_access(vcpu, msr_info, false)) {

			break;

		}



		/* Not a known PMU MSR. */

		return 1;

	}



	return 0;

}



static void setup_fixed_pmc_eventsel(struct kvm_pmu *pmu)

{

	size_t size = ARRAY_SIZE(fixed_pmc_events);