Re: [PATCH 4/4] KVM: guest_memfd: Stop returning struct page from PFN lookup

[Yan Zhao <yan.y.zhao@intel.com>]

Hi Ackerley,

> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 6c941aaa10c63..e5d637a5ec558 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1613,7 +1613,7 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd)
>  	enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
>  	struct kvm_pgtable *pgt = s2fd->vcpu->arch.hw_mmu->pgt;
>  	unsigned long mmu_seq;
> -	struct page *page;
Just drop the page should be ok, since
> +	struct page *page = NULL;
>  	struct kvm *kvm = s2fd->vcpu->kvm;
>  	void *memcache = NULL;
>  	kvm_pfn_t pfn;
> @@ -1641,7 +1641,7 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd)
>  	/* Pairs with the smp_wmb() in kvm_mmu_invalidate_end(). */
>  	smp_rmb();
>  
> -	ret = kvm_gmem_get_pfn(kvm, s2fd->memslot, gfn, &pfn, &page, NULL);
> +	ret = kvm_gmem_get_pfn(kvm, s2fd->memslot, gfn, &pfn, NULL);
>  	if (ret) {
>  		kvm_prepare_memory_fault_exit(s2fd->vcpu, s2fd->fault_ipa, PAGE_SIZE,
>  					      write_fault, exec_fault, false);
here missed a hunk:
 out_unlock:
-       kvm_release_faultin_page(kvm, page, !!ret, prot & KVM_PGTABLE_PROT_W);
        kvm_fault_unlock(kvm);

I will fully test this series tomorrow.