linux-kernel - Re: [PATCH kvm-next V11 4/7] KVM: guest_memfd: Use guest mem inodes instead of anonymous inodes

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Message-ID: <4db9239a-efe3-43b2-b7b4-af497eb9ee28@redhat.com>
Date: Thu, 28 Aug 2025 12:06:12 +0200
From: David Hildenbrand <david@...hat.com>
To: Ackerley Tng <ackerleytng@...gle.com>, Shivank Garg <shivankg@....com>,
 willy@...radead.org, akpm@...ux-foundation.org, pbonzini@...hat.com,
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Subject: Re: [PATCH kvm-next V11 4/7] KVM: guest_memfd: Use guest mem inodes
 instead of anonymous inodes

On 28.08.25 00:43, Ackerley Tng wrote:
> Shivank Garg <shivankg@....com> writes:
> 
>>
>> [...snip...]
>>
> 
> I meant to send this to you before this version went out but you were
> too quick!
> 
> Here's a new version, Fuad and I reviewed this again internally. The
> changes are:
> 
> + Sort linux/pseudo_fs.h after linux/pagemap.h (alphabetical)
> + Don't set MNT_NOEXEC on the mount, since SB_I_NOEXEC was already set
>    on the superblock
> + Rename kvm_gmem_inode_make_secure_inode() to kvm_gmem_inode_create()
>      + Emphasizes that there is a creation in this function
>      + Remove "secure" from the function name to remove confusion that
>        there may be a "non-secure" version
> + In kvm_gmem_inode_create_getfile()'s error path, return ERR_PTR(err)
>    directly instead of having a goto
> 
> 
>  From ada9814b216eac129ed44dffd3acf76fce2cc08a Mon Sep 17 00:00:00 2001
> From: Ackerley Tng <ackerleytng@...gle.com>
> Date: Sun, 13 Jul 2025 17:43:35 +0000
> Subject: [PATCH] KVM: guest_memfd: Use guest mem inodes instead of anonymous
>   inodes
> 
> guest_memfd's inode represents memory the guest_memfd is
> providing. guest_memfd's file represents a struct kvm's view of that
> memory.
> 
> Using a custom inode allows customization of the inode teardown
> process via callbacks. For example, ->evict_inode() allows
> customization of the truncation process on file close, and
> ->destroy_inode() and ->free_inode() allow customization of the inode
> freeing process.
> 
> Customizing the truncation process allows flexibility in management of
> guest_memfd memory and customization of the inode freeing process
> allows proper cleanup of memory metadata stored on the inode.
> 
> Memory metadata is more appropriately stored on the inode (as opposed
> to the file), since the metadata is for the memory and is not unique
> to a specific binding and struct kvm.
> 
> Co-developed-by: Fuad Tabba <tabba@...gle.com>
> Signed-off-by: Fuad Tabba <tabba@...gle.com>
> Signed-off-by: Shivank Garg <shivankg@....com>
> Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb