From: Sean Christopherson <seanjc@google.com>
To: Quentin Perret <qperret@google.com>
Cc: David Hildenbrand <david@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Fuad Tabba <tabba@google.com>,
kvm@vger.kernel.org, kvmarm@lists.linux.dev,
pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au,
anup@brainfault.org, paul.walmsley@sifive.com,
palmer@dabbelt.com, aou@eecs.berkeley.edu,
viro@zeniv.linux.org.uk, brauner@kernel.org,
akpm@linux-foundation.org, xiaoyao.li@intel.com,
yilun.xu@intel.com, chao.p.peng@linux.intel.com,
jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com,
yu.c.zhang@linux.intel.com, isaku.yamahata@intel.com,
mic@digikod.net, vbabka@suse.cz, vannapurve@google.com,
ackerleytng@google.com, mail@maciej.szmigiero.name,
michael.roth@amd.com, wei.w.wang@intel.com,
liam.merwick@oracle.com, isaku.yamahata@gmail.com,
kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com,
steven.price@arm.com, quic_mnalajal@quicinc.com,
quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com,
quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com,
quic_pheragu@quicinc.com, catalin.marinas@arm.com,
james.morse@arm.com, yuzenghui@huawei.com,
oliver.upton@linux.dev, maz@kernel.org, will@kernel.org,
keirf@google.com, linux-mm@kvack.org
Subject: Re: folio_mmapped
Date: Mon, 4 Mar 2024 11:04:50 -0800 [thread overview]
Message-ID: <ZeYbUjiIkPevjrRR@google.com> (raw)
In-Reply-To: <ZeXAOit6O0stdxw3@google.com>
On Mon, Mar 04, 2024, Quentin Perret wrote:
> > As discussed in the sub-thread, that might still be required.
> >
> > One could think about completely forbidding GUP on these mmap'ed
> > guest-memfds. But likely, there might be use cases in the future where you
> > want to use GUP on shared memory inside a guest_memfd.
> >
> > (the iouring example I gave might currently not work because
> > FOLL_PIN|FOLL_LONGTERM|FOLL_WRITE only works on shmem+hugetlb, and
> > guest_memfd will likely not be detected as shmem; 8ac268436e6d contains some
> > details)
>
> Perhaps it would be wise to start with GUP being forbidden if the
> current users do not need it (not sure if that is the case in Android,
> I'll check) ? We can always relax this constraint later when/if the
> use-cases arise, which is obviously much harder to do the other way
> around.
+1000. At least on the KVM side, I would like to be as conservative as possible
when it comes to letting anything other than the guest access guest_memfd.
next prev parent reply other threads:[~2024-03-04 19:04 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240222161047.402609-1-tabba@google.com>
[not found] ` <20240222141602976-0800.eberman@hu-eberman-lv.qualcomm.com>
2024-02-23 0:35 ` folio_mmapped Matthew Wilcox
2024-02-26 9:28 ` folio_mmapped David Hildenbrand
2024-02-26 21:14 ` folio_mmapped Elliot Berman
2024-02-27 14:59 ` folio_mmapped David Hildenbrand
2024-02-28 10:48 ` folio_mmapped Quentin Perret
2024-02-28 11:11 ` folio_mmapped David Hildenbrand
2024-02-28 12:44 ` folio_mmapped Quentin Perret
2024-02-28 13:00 ` folio_mmapped David Hildenbrand
2024-02-28 13:34 ` folio_mmapped Quentin Perret
2024-02-28 18:43 ` folio_mmapped Elliot Berman
2024-02-28 18:51 ` Quentin Perret
2024-02-29 10:04 ` folio_mmapped David Hildenbrand
2024-02-29 19:01 ` folio_mmapped Fuad Tabba
2024-03-01 0:40 ` folio_mmapped Elliot Berman
2024-03-01 11:16 ` folio_mmapped David Hildenbrand
2024-03-04 12:53 ` folio_mmapped Quentin Perret
2024-03-04 20:22 ` folio_mmapped David Hildenbrand
2024-03-01 11:06 ` folio_mmapped David Hildenbrand
2024-03-04 12:36 ` folio_mmapped Quentin Perret
2024-03-04 19:04 ` Sean Christopherson [this message]
2024-03-04 20:17 ` folio_mmapped David Hildenbrand
2024-03-04 21:43 ` folio_mmapped Elliot Berman
2024-03-04 21:58 ` folio_mmapped David Hildenbrand
2024-03-19 9:47 ` folio_mmapped Quentin Perret
2024-03-19 9:54 ` folio_mmapped David Hildenbrand
2024-03-18 17:06 ` folio_mmapped Vishal Annapurve
2024-03-18 22:02 ` folio_mmapped David Hildenbrand
[not found] ` <CAGtprH8B8y0Khrid5X_1twMce7r-Z7wnBiaNOi-QwxVj4D+L3w@mail.gmail.com>
2024-03-19 0:10 ` folio_mmapped Sean Christopherson
2024-03-19 10:26 ` folio_mmapped David Hildenbrand
2024-03-19 13:19 ` folio_mmapped David Hildenbrand
2024-03-19 14:31 ` folio_mmapped Will Deacon
2024-03-19 23:54 ` folio_mmapped Elliot Berman
2024-03-22 16:36 ` Will Deacon
2024-03-22 18:46 ` Elliot Berman
2024-03-27 19:31 ` Will Deacon
[not found] ` <2d6fc3c0-a55b-4316-90b8-deabb065d007@redhat.com>
2024-03-22 21:21 ` folio_mmapped David Hildenbrand
2024-03-26 22:04 ` folio_mmapped Elliot Berman
2024-03-27 19:34 ` folio_mmapped Will Deacon
2024-03-28 9:06 ` folio_mmapped David Hildenbrand
2024-03-28 10:10 ` folio_mmapped Quentin Perret
2024-03-28 10:32 ` folio_mmapped David Hildenbrand
2024-03-28 10:58 ` folio_mmapped Quentin Perret
2024-03-28 11:41 ` folio_mmapped David Hildenbrand
2024-03-29 18:38 ` folio_mmapped Vishal Annapurve
2024-04-04 0:15 ` folio_mmapped Sean Christopherson
2024-03-19 15:04 ` folio_mmapped Sean Christopherson
2024-03-22 17:16 ` folio_mmapped David Hildenbrand
2024-02-26 9:03 ` [RFC PATCH v1 00/26] KVM: Restricted mapping of guest_memfd at the host and pKVM/arm64 support Fuad Tabba
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