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KVM: VMX: Drop explicit zeroing of MSR guest values at vCPU creation

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Don't zero out user return and nested MSRs during vCPU creation, and
instead rely on vcpu_vmx being zero-allocated.  Explicitly zeroing MSRs
is not wrong, and is in fact necessary if KVM ever emulates vCPU RESET
outside of vCPU creation, but zeroing only a subset of MSRs is confusing.

Poking directly into KVM's backing is also undesirable in that it doesn't
scale and is error prone.  Ideally KVM would have a common RESET path for
all MSRs, e.g. by expanding kvm_set_msr(), which would obviate the need
for this out-of-bad code (to support standalone RESET).

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210921000303.400537-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-09-20 17:03:00 -07:00 committed by Paolo Bonzini
parent 583d369b36
commit d06567353e
1 changed files with 1 additions and 5 deletions
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6
arch/x86/kvm/vmx/vmx.c
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@ -6837,10 +6837,8 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
goto free_vpid;
}
for (i = 0; i < kvm_nr_uret_msrs; ++i) {
vmx->guest_uret_msrs[i].data = 0;
for (i = 0; i < kvm_nr_uret_msrs; ++i)
vmx->guest_uret_msrs[i].mask = -1ull;
}
if (boot_cpu_has(X86_FEATURE_RTM)) {
/*
* TSX_CTRL_CPUID_CLEAR is handled in the CPUID interception.
@ -6897,8 +6895,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
if (nested)
memcpy(&vmx->nested.msrs, &vmcs_config.nested, sizeof(vmx->nested.msrs));
else
memset(&vmx->nested.msrs, 0, sizeof(vmx->nested.msrs));
vcpu_setup_sgx_lepubkeyhash(vcpu);