Re: [PATCH v10 041/108] KVM: x86/tdp_mmu: refactor kvm_tdp_mmu_map()

Huang, Kai
2022-11-16T09:42:43Z

On Sat, 2022-10-29 at 23:22 -0700, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
>
> Factor out non-leaf SPTE population logic from kvm_tdp_mmu_map(). MapGPA
> hypercall needs to populate non-leaf SPTE to record which GPA, private or
> shared, is allowed in the leaf EPT entry.

Is this patch still valid/needed since you have changed to use XArray to store
whether GFN is private or shared?

>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/kvm/mmu/tdp_mmu.c | 26 +++++++++++++++++++-------
> 1 file changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 3325633b1cb5..11b0ec8aebe2 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -1157,6 +1157,24 @@ static int tdp_mmu_link_sp(struct kvm *kvm, struct tdp_iter *iter,
> return 0;
> }
>
> +static int tdp_mmu_populate_nonleaf(struct kvm_vcpu *vcpu, struct tdp_iter *iter,
> + bool account_nx)
> +{
> + struct kvm_mmu_page *sp;
> + int ret;
> +
> + KVM_BUG_ON(is_shadow_present_pte(iter->old_spte), vcpu->kvm);
> + KVM_BUG_ON(is_removed_spte(iter->old_spte), vcpu->kvm);
> +
> + sp = tdp_mmu_alloc_sp(vcpu);
> + tdp_mmu_init_child_sp(sp, iter);
> +
> + ret = tdp_mmu_link_sp(vcpu->kvm, iter, sp, account_nx, true);
> + if (ret)
> + tdp_mmu_free_sp(sp);
> + return ret;
> +}
> +
> /*
> * Handle a TDP page fault (NPT/EPT violation/misconfiguration) by installing
> * page tables and SPTEs to translate the faulting guest physical address.
> @@ -1165,7 +1183,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> {
> struct kvm_mmu *mmu = vcpu->arch.mmu;
> struct tdp_iter iter;
> - struct kvm_mmu_page *sp;
> int ret;
>
> kvm_mmu_hugepage_adjust(vcpu, fault);
> @@ -1211,13 +1228,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> if (is_removed_spte(iter.old_spte))
> break;
>
> - sp = tdp_mmu_alloc_sp(vcpu);
> - tdp_mmu_init_child_sp(sp, &iter);
> -
> - if (tdp_mmu_link_sp(vcpu->kvm, &iter, sp, account_nx, true)) {
> - tdp_mmu_free_sp(sp);
> + if (tdp_mmu_populate_nonleaf(vcpu, &iter, account_nx))
> break;
> - }
> }
> }
>