linux-kernel - [PATCH V10 17/18] KVM: x86/cpuid: Refactor host/guest CPU model consistency check

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Message-Id: <20210806133802.3528-18-lingshan.zhu@intel.com>
Date:   Fri,  6 Aug 2021 21:38:01 +0800
From:   Zhu Lingshan <lingshan.zhu@...el.com>
To:     peterz@...radead.org, pbonzini@...hat.com
Cc:     bp@...en8.de, seanjc@...gle.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        kan.liang@...ux.intel.com, ak@...ux.intel.com,
        wei.w.wang@...el.com, eranian@...gle.com, liuxiangdong5@...wei.com,
        linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
        like.xu.linux@...il.com, boris.ostrvsky@...cle.com,
        Like Xu <like.xu@...ux.intel.com>,
        Zhu Lingshan <lingshan.zhu@...el.com>
Subject: [PATCH V10 17/18] KVM: x86/cpuid: Refactor host/guest CPU model consistency check

From: Like Xu <like.xu@...ux.intel.com>

For the same purpose, the leagcy intel_pmu_lbr_is_compatible() can be
renamed for reuse by more callers, and remove the comment about LBR
use case can be deleted by the way.

Signed-off-by: Like Xu <like.xu@...ux.intel.com>
Signed-off-by: Zhu Lingshan <lingshan.zhu@...el.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kvm/cpuid.h         |  5 +++++
 arch/x86/kvm/vmx/pmu_intel.c | 12 +-----------
 arch/x86/kvm/vmx/vmx.c       |  2 +-
 arch/x86/kvm/vmx/vmx.h       |  1 -
 4 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index c99edfff7f82..439ce776b9a0 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -143,6 +143,11 @@ static inline int guest_cpuid_model(struct kvm_vcpu *vcpu)
 	return x86_model(best->eax);
 }
 
+static inline bool cpuid_model_is_consistent(struct kvm_vcpu *vcpu)
+{
+	return boot_cpu_data.x86_model == guest_cpuid_model(vcpu);
+}
+
 static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpuid_entry2 *best;
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 05bc218c08df..a77d5a5f2ba5 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -173,16 +173,6 @@ static inline struct kvm_pmc *get_fw_gp_pmc(struct kvm_pmu *pmu, u32 msr)
 	return get_gp_pmc(pmu, msr, MSR_IA32_PMC0);
 }
 
-bool intel_pmu_lbr_is_compatible(struct kvm_vcpu *vcpu)
-{
-	/*
-	 * As a first step, a guest could only enable LBR feature if its
-	 * cpu model is the same as the host because the LBR registers
-	 * would be pass-through to the guest and they're model specific.
-	 */
-	return boot_cpu_data.x86_model == guest_cpuid_model(vcpu);
-}
-
 bool intel_pmu_lbr_is_enabled(struct kvm_vcpu *vcpu)
 {
 	struct x86_pmu_lbr *lbr = vcpu_to_lbr_records(vcpu);
@@ -578,7 +568,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
 
 	nested_vmx_pmu_entry_exit_ctls_update(vcpu);
 
-	if (intel_pmu_lbr_is_compatible(vcpu))
+	if (cpuid_model_is_consistent(vcpu))
 		x86_perf_get_lbr(&lbr_desc->records);
 	else
 		lbr_desc->records.nr = 0;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d8552dbece6f..d0af51c1389d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2221,7 +2221,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 			if ((data & PMU_CAP_LBR_FMT) !=
 			    (vmx_get_perf_capabilities() & PMU_CAP_LBR_FMT))
 				return 1;
-			if (!intel_pmu_lbr_is_compatible(vcpu))
+			if (!cpuid_model_is_consistent(vcpu))
 				return 1;
 		}
 		ret = kvm_set_msr_common(vcpu, msr_info);
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 86fa1a08feca..bd2922c8046f 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -95,7 +95,6 @@ union vmx_exit_reason {
 #define vcpu_to_lbr_records(vcpu) (&to_vmx(vcpu)->lbr_desc.records)
 
 void intel_pmu_cross_mapped_check(struct kvm_pmu *pmu);
-bool intel_pmu_lbr_is_compatible(struct kvm_vcpu *vcpu);
 bool intel_pmu_lbr_is_enabled(struct kvm_vcpu *vcpu);
 
 int intel_pmu_create_guest_lbr_event(struct kvm_vcpu *vcpu);
-- 
2.27.0