linux-kernel - Re: [PATCH v3 2/6] KVM: guest_memfd: Remove partial hugepage handling from kvm_gmem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aWTBPjl2TNEczy2C@yzhao56-desk.sh.intel.com>
Date: Mon, 12 Jan 2026 17:39:10 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: Michael Roth <michael.roth@....com>
CC: <kvm@...r.kernel.org>, <linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>, <thomas.lendacky@....com>,
	<pbonzini@...hat.com>, <seanjc@...gle.com>, <vbabka@...e.cz>,
	<ashish.kalra@....com>, <liam.merwick@...cle.com>, <david@...hat.com>,
	<vannapurve@...gle.com>, <ackerleytng@...gle.com>, <aik@....com>,
	<ira.weiny@...el.com>, <pankaj.gupta@....com>, Kai Huang
	<kai.huang@...el.com>
Subject: Re: [PATCH v3 2/6] KVM: guest_memfd: Remove partial hugepage
 handling from kvm_gmem_populate()

Tested-by: Yan Zhao <yan.y.zhao@...el.com>
Reviewed-by: Yan Zhao <yan.y.zhao@...el.com>

> @@ -848,7 +857,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long
>  	filemap_invalidate_lock(file->f_mapping);
>  
>  	npages = min_t(ulong, slot->npages - (start_gfn - slot->base_gfn), npages);
> -	for (i = 0; i < npages; i += (1 << max_order)) {
> +	for (i = 0; i < npages; i++) {
>  		struct folio *folio;
>  		gfn_t gfn = start_gfn + i;
>  		pgoff_t index = kvm_gmem_get_index(slot, gfn);
> @@ -860,7 +869,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long
>  			break;
>  		}
>  
> -		folio = __kvm_gmem_get_pfn(file, slot, index, &pfn, &is_prepared, &max_order);
> +		folio = __kvm_gmem_get_pfn(file, slot, index, &pfn, &is_prepared, NULL);
>  		if (IS_ERR(folio)) {
>  			ret = PTR_ERR(folio);
>  			break;
> @@ -874,20 +883,15 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long
>  		}
>  
>  		folio_unlock(folio);
> -		WARN_ON(!IS_ALIGNED(gfn, 1 << max_order) ||
> -			(npages - i) < (1 << max_order));
>  
>  		ret = -EINVAL;
Nit: Can move this "ret = -EINVAL" to inside the "if". i.e.,

               if (!kvm_gmem_range_is_private(gi, index, 1, kvm, gfn)) {
                       ret = -EINVAL;
                       goto put_folio_and_exit;
               }


> -		while (!kvm_range_has_memory_attributes(kvm, gfn, gfn + (1 << max_order),
> -							KVM_MEMORY_ATTRIBUTE_PRIVATE,
> -							KVM_MEMORY_ATTRIBUTE_PRIVATE)) {
> -			if (!max_order)
> -				goto put_folio_and_exit;
> -			max_order--;
> -		}
> +		if (!kvm_range_has_memory_attributes(kvm, gfn, gfn + 1,
> +						     KVM_MEMORY_ATTRIBUTE_PRIVATE,
> +						     KVM_MEMORY_ATTRIBUTE_PRIVATE))
> +			goto put_folio_and_exit;
>  
>  		p = src ? src + i * PAGE_SIZE : NULL;
> -		ret = post_populate(kvm, gfn, pfn, p, max_order, opaque);
> +		ret = post_populate(kvm, gfn, pfn, p, opaque);
>  		if (!ret)
>  			kvm_gmem_mark_prepared(folio);
>  
> -- 
> 2.25.1
>