From: Andy Lutomirski <luto@kernel.org>
To: "Adalbert Lazăr" <alazar@bitdefender.com>
Cc: Linux-MM <linux-mm@kvack.org>,
"Linux API" <linux-api@vger.kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Alexander Graf" <graf@amazon.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Jerome Glisse" <jglisse@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Mihai Donțu" <mdontu@bitdefender.com>,
"Mircea Cirjaliu" <mcirjaliu@bitdefender.com>,
"Andy Lutomirski" <luto@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Sargun Dhillon" <sargun@sargun.me>,
"Aleksa Sarai" <cyphar@cyphar.com>,
"Oleg Nesterov" <oleg@redhat.com>, "Jann Horn" <jannh@google.com>,
"Kees Cook" <keescook@chromium.org>,
"Matthew Wilcox" <willy@infradead.org>,
"Christian Brauner" <christian.brauner@ubuntu.com>
Subject: Re: [RESEND RFC PATCH 0/5] Remote mapping
Date: Fri, 4 Sep 2020 12:39:10 -0700 [thread overview]
Message-ID: <CALCETrVc0RCcvVhxL=x2ics-Snhh1F6o5M7EVsA2rPYcaynMyA@mail.gmail.com> (raw)
In-Reply-To: <20200904113116.20648-1-alazar@bitdefender.com>
On Fri, Sep 4, 2020 at 4:41 AM Adalbert Lazăr <alazar@bitdefender.com> wrote:
>
> This patchset adds support for the remote mapping feature.
> Remote mapping, as its name suggests, is a means for transparent and
> zero-copy access of a remote process' address space.
> access of a remote process' address space.
>
I think this is very clever, but I find myself wondering what happens
if people start trying to abuse this by, for example, setting up a
remote mapping pointing to fun regions like userfaultfd or another
remote mapping.
I'm a little concerned that it's actually too clever and that maybe a
more straightforward solution should be investigated. I personally
rather dislike the KVM model in which the guest address space mirrors
the host (QEMU) address space rather than being its own thing. In
particular, the current model means that extra-special-strange
mappings like SEV-encrypted memory are required to be present in the
QEMU page tables in order for the guest to see them.
(If I had noticed that last bit before it went upstream, I would have
NAKked it. I would still like to see it deprecated and ideally
eventually removed from the kernel. We have absolutely no business
creating incoherent mappings like this.)
--Andy
next prev parent reply other threads:[~2020-09-04 19:39 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 11:31 [RESEND RFC PATCH 0/5] Remote mapping Adalbert Lazăr
2020-09-04 11:31 ` [RESEND RFC PATCH 1/5] mm: add atomic capability to zap_details Adalbert Lazăr
2020-09-04 11:31 ` [RESEND RFC PATCH 2/5] mm: let the VMA decide how zap_pte_range() acts on mapped pages Adalbert Lazăr
2020-09-04 11:31 ` [RESEND RFC PATCH 3/5] mm/mmu_notifier: remove lockdep map, allow mmu notifier to be used in nested scenarios Adalbert Lazăr
2020-09-04 12:03 ` Jason Gunthorpe
2020-09-04 11:31 ` [RESEND RFC PATCH 4/5] mm/remote_mapping: use a pidfd to access memory belonging to unrelated process Adalbert Lazăr
2020-09-04 17:55 ` Oleg Nesterov
2020-09-07 14:30 ` Oleg Nesterov
2020-09-07 15:16 ` Adalbert Lazăr
2020-09-09 8:32 ` Mircea CIRJALIU - MELIU
2020-09-10 16:43 ` Oleg Nesterov
2020-09-07 15:02 ` Christian Brauner
2020-09-07 16:04 ` Mircea CIRJALIU - MELIU
2020-09-04 11:31 ` [RESEND RFC PATCH 5/5] pidfd_mem: implemented remote memory mapping system call Adalbert Lazăr
2020-09-04 19:18 ` Florian Weimer
2020-09-07 14:55 ` Christian Brauner
2020-09-04 12:11 ` [RESEND RFC PATCH 0/5] Remote mapping Jason Gunthorpe
2020-09-04 13:24 ` Mircea CIRJALIU - MELIU
2020-09-04 13:39 ` Jason Gunthorpe
2020-09-04 14:18 ` Mircea CIRJALIU - MELIU
2020-09-04 14:39 ` Jason Gunthorpe
2020-09-04 15:40 ` Mircea CIRJALIU - MELIU
2020-09-04 16:11 ` Jason Gunthorpe
2020-09-04 19:41 ` Matthew Wilcox
2020-09-04 19:49 ` Jason Gunthorpe
2020-09-04 20:08 ` Paolo Bonzini
2020-12-01 18:01 ` Jason Gunthorpe
2020-09-04 19:19 ` Florian Weimer
2020-09-04 20:18 ` Paolo Bonzini
2020-09-07 8:33 ` Christian Brauner
2020-09-04 19:39 ` Andy Lutomirski [this message]
2020-09-04 20:09 ` Paolo Bonzini
2020-09-04 20:34 ` Andy Lutomirski
2020-09-04 21:58 ` Paolo Bonzini
2020-09-04 23:17 ` Andy Lutomirski
2020-09-05 18:27 ` Paolo Bonzini
2020-09-07 8:38 ` Christian Brauner
2020-09-07 12:41 ` Mircea CIRJALIU - MELIU
2020-09-07 7:05 ` Christoph Hellwig
2020-09-07 8:44 ` Paolo Bonzini
2020-09-07 10:25 ` Mircea CIRJALIU - MELIU
2020-09-07 15:05 ` Christian Brauner
2020-09-07 20:43 ` Andy Lutomirski
2020-09-09 11:38 ` Stefan Hajnoczi
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