2022-08-30 13:42:07

by Vitaly Kuznetsov

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 <[email protected]>
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <[email protected]>
---
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

2022-09-05 17:17:25

by Wei Liu

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

On Tue, Aug 30, 2022 at 03:37:07PM +0200, Vitaly Kuznetsov wrote:
> 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 <[email protected]>
> [sean: split to separate patch]
> Signed-off-by: Sean Christopherson <[email protected]>

Reviewed-by: Wei Liu <[email protected]>