From: David Hildenbrand <david@redhat.com>
To: Fuad Tabba <tabba@google.com>, Patrick Roy <roypat@amazon.co.uk>
Cc: seanjc@google.com, pbonzini@redhat.com,
akpm@linux-foundation.org, dwmw@amazon.co.uk, rppt@kernel.org,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
willy@infradead.org, graf@amazon.com, derekmn@amazon.com,
kalyazin@amazon.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
dmatlack@google.com, chao.p.peng@linux.intel.com,
xmarcalx@amazon.co.uk
Subject: Re: [RFC PATCH 8/8] kvm: gmem: Allow restricted userspace mappings
Date: Tue, 9 Jul 2024 23:13:25 +0200 [thread overview]
Message-ID: <47ce1b10-e031-4ac1-b88f-9d4194533745@redhat.com> (raw)
In-Reply-To: <CA+EHjTynVpsqsudSVRgOBdNSP_XjdgKQkY_LwdqvPkpJAnAYKg@mail.gmail.com>
On 09.07.24 16:48, Fuad Tabba wrote:
> Hi Patrick,
>
> On Tue, Jul 9, 2024 at 2:21 PM Patrick Roy <roypat@amazon.co.uk> wrote:
>>
>> Allow mapping guest_memfd into userspace. Since AS_INACCESSIBLE is set
>> on the underlying address_space struct, no GUP of guest_memfd will be
>> possible.
>
> This patch allows mapping guest_memfd() unconditionally. Even if it's
> not guppable, there are other reasons why you wouldn't want to allow
> this. Maybe a config flag to gate it? e.g.,
As discussed with Jason, maybe not the direction we want to take with
guest_memfd.
If it's private memory, it shall not be mapped. Also not via magic
config options.
We'll likely discuss some of that in the meeting MM tomorrow I guess
(having both shared and private memory in guest_memfd).
Note that just from staring at this commit, I don't understand the
motivation *why* we would want to do that.
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2024-07-09 21:13 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-09 13:20 [RFC PATCH 0/8] Unmapping guest_memfd from Direct Map Patrick Roy
2024-07-09 13:20 ` [RFC PATCH 1/8] kvm: Allow reading/writing gmem using kvm_{read,write}_guest Patrick Roy
2024-07-09 13:20 ` [RFC PATCH 2/8] kvm: use slowpath in gfn_to_hva_cache if memory is private Patrick Roy
2024-07-09 13:20 ` [RFC PATCH 3/8] kvm: pfncache: enlighten about gmem Patrick Roy
2024-07-09 14:36 ` David Woodhouse
2024-07-10 9:49 ` Patrick Roy
2024-07-10 10:20 ` David Woodhouse
2024-07-10 10:46 ` Patrick Roy
2024-07-10 10:50 ` David Woodhouse
2024-07-09 13:20 ` [RFC PATCH 4/8] kvm: x86: support walking guest page tables in gmem Patrick Roy
2024-07-09 13:20 ` [RFC PATCH 5/8] kvm: gmem: add option to remove guest private memory from direct map Patrick Roy
2024-07-10 7:31 ` Mike Rapoport
2024-07-10 9:50 ` Patrick Roy
2024-07-09 13:20 ` [RFC PATCH 6/8] kvm: gmem: Temporarily restore direct map entries when needed Patrick Roy
2024-07-11 6:25 ` Paolo Bonzini
2024-07-09 13:20 ` [RFC PATCH 7/8] mm: secretmem: use AS_INACCESSIBLE to prohibit GUP Patrick Roy
2024-07-09 21:09 ` David Hildenbrand
2024-07-10 7:32 ` Mike Rapoport
2024-07-10 9:50 ` Patrick Roy
2024-07-10 21:14 ` David Hildenbrand
2024-07-09 13:20 ` [RFC PATCH 8/8] kvm: gmem: Allow restricted userspace mappings Patrick Roy
2024-07-09 14:48 ` Fuad Tabba
2024-07-09 21:13 ` David Hildenbrand [this message]
2024-07-10 9:51 ` Patrick Roy
2024-07-10 21:12 ` David Hildenbrand
2024-07-10 21:53 ` Sean Christopherson
2024-07-10 21:56 ` David Hildenbrand
2024-07-12 15:59 ` Patrick Roy
2024-07-30 10:15 ` David Hildenbrand
2024-08-01 10:30 ` Patrick Roy
2024-07-22 12:28 ` [RFC PATCH 0/8] Unmapping guest_memfd from Direct Map Vlastimil Babka (SUSE)
2024-07-26 6:55 ` Patrick Roy
2024-07-30 10:17 ` David Hildenbrand
2024-07-26 16:44 ` Yosry Ahmed
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