linux-kernel - [PATCH v6 03/33] KVM: x86: Zero out entire Hyper-V CPUID cache before processing entries

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Date:   Tue, 30 Aug 2022 15:37:07 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Yuan Yao <yuan.yao@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v6 03/33] KVM: x86: Zero out entire Hyper-V CPUID cache before processing entries

Wipe the whole 'hv_vcpu->cpuid_cache' with memset() instead of having to
zero each particular member when the corresponding CPUID entry was not
found.

No functional change intended.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/hyperv.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index ed804447589c..611c349a08bf 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2005,31 +2005,24 @@ void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu)
 
 	hv_vcpu = to_hv_vcpu(vcpu);
 
+	memset(&hv_vcpu->cpuid_cache, 0, sizeof(hv_vcpu->cpuid_cache));
+
 	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_FEATURES);
 	if (entry) {
 		hv_vcpu->cpuid_cache.features_eax = entry->eax;
 		hv_vcpu->cpuid_cache.features_ebx = entry->ebx;
 		hv_vcpu->cpuid_cache.features_edx = entry->edx;
-	} else {
-		hv_vcpu->cpuid_cache.features_eax = 0;
-		hv_vcpu->cpuid_cache.features_ebx = 0;
-		hv_vcpu->cpuid_cache.features_edx = 0;
 	}
 
 	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_ENLIGHTMENT_INFO);
 	if (entry) {
 		hv_vcpu->cpuid_cache.enlightenments_eax = entry->eax;
 		hv_vcpu->cpuid_cache.enlightenments_ebx = entry->ebx;
-	} else {
-		hv_vcpu->cpuid_cache.enlightenments_eax = 0;
-		hv_vcpu->cpuid_cache.enlightenments_ebx = 0;
 	}
 
 	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES);
 	if (entry)
 		hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax;
-	else
-		hv_vcpu->cpuid_cache.syndbg_cap_eax = 0;
 }
 
 int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)
-- 
2.37.2