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KVM: nSVM: Drop pointless pdptrs_changed() check on nested transition

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Remove the "PDPTRs unchanged" check to skip PDPTR loading during nested
SVM transitions as it's not at all an optimization.  Reading guest memory
to get the PDPTRs isn't magically cheaper by doing it in pdptrs_changed(),
and if the PDPTRs did change, KVM will end up doing the read twice.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210607090203.133058-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-06-07 12:01:57 +03:00 • committed by Paolo Bonzini
parent bcb72d0627
commit a36dbec67e
1 changed files with 2 additions and 4 deletions
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6
arch/x86/kvm/svm/nested.c
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@ -391,10 +391,8 @@ static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
return -EINVAL;
if (!nested_npt && is_pae_paging(vcpu) &&
(cr3 != kvm_read_cr3(vcpu) || pdptrs_changed(vcpu))) {
if (CC(!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3)))
return -EINVAL;
}
CC(!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3)))
return -EINVAL;
/*
* TODO: optimize unconditional TLB flush/MMU sync here and in