linux-kernel - Re: [RFC PATCH 27/39] KVM: guest_memfd: Allow mmapping guest

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: <Z8eLs-53UwKHfEeK@x1.local>
Date: Tue, 4 Mar 2025 18:24:35 -0500
From: Peter Xu <peterx@...hat.com>
To: Ackerley Tng <ackerleytng@...gle.com>
Cc: tabba@...gle.com, quic_eberman@...cinc.com, roypat@...zon.co.uk,
	jgg@...dia.com, david@...hat.com, rientjes@...gle.com,
	fvdl@...gle.com, jthoughton@...gle.com, seanjc@...gle.com,
	pbonzini@...hat.com, zhiquan1.li@...el.com, fan.du@...el.com,
	jun.miao@...el.com, isaku.yamahata@...el.com, muchun.song@...ux.dev,
	mike.kravetz@...cle.com, erdemaktas@...gle.com,
	vannapurve@...gle.com, qperret@...gle.com, jhubbard@...dia.com,
	willy@...radead.org, shuah@...nel.org, brauner@...nel.org,
	bfoster@...hat.com, kent.overstreet@...ux.dev, pvorel@...e.cz,
	rppt@...nel.org, richard.weiyang@...il.com, anup@...infault.org,
	haibo1.xu@...el.com, ajones@...tanamicro.com, vkuznets@...hat.com,
	maciej.wieczor-retman@...el.com, pgonda@...gle.com,
	oliver.upton@...ux.dev, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, kvm@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-fsdevel@...ck.org
Subject: Re: [RFC PATCH 27/39] KVM: guest_memfd: Allow mmapping guest_memfd
 files

On Tue, Sep 10, 2024 at 11:43:58PM +0000, Ackerley Tng wrote:
> @@ -790,6 +791,9 @@ static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
>  	 */
>  	filemap_invalidate_lock(inode->i_mapping);
>  
> +	/* TODO: Check if even_cows should be 0 or 1 */
> +	unmap_mapping_range(inode->i_mapping, start, len, 0);

Should be s/start/offset/ here, or should expect some filemap crash assert
on non-zero mapcounts (when it starts to matter).

Btw, it would be nice if the new version would allow kvm to be compiled as
a module.  Currently it uses a lot of mm functions that are not yet
exported, so AFAIU it will only build if kvm is builtin.

Thanks,

-- 
Peter Xu