linux-kernel - Re: Rename restrictedmem => guardedmem? (was: Re: [PATCH v10 0/9] KVM: mm: fd-based approach for supporting KVM)

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Message-ID: <ZD12htq6dWg0tg2e@google.com>
Date:   Mon, 17 Apr 2023 09:40:38 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     Chao Peng <chao.p.peng@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "Maciej S . Szmigiero" <mail@...iej.szmigiero.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        dhildenb@...hat.com, Quentin Perret <qperret@...gle.com>,
        tabba@...gle.com, Michael Roth <michael.roth@....com>,
        wei.w.wang@...el.com, Mike Rapoport <rppt@...nel.org>,
        Liam Merwick <liam.merwick@...cle.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Ackerley Tng <ackerleytng@...gle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Rename restrictedmem => guardedmem? (was: Re: [PATCH v10 0/9]
 KVM: mm: fd-based approach for supporting KVM)

On Mon, Apr 17, 2023, David Hildenbrand wrote:
> On 17.04.23 17:40, Sean Christopherson wrote:
> > I want to start referring to the code/patches by its syscall/implementation name
> > instead of "UPM", as "UPM" is (a) very KVM centric, (b) refers to the broader effort
> > and not just the non-KVM code, and (c) will likely be confusing for future reviewers
> > since there's nothing in the code that mentions "UPM" in any way.
> > 
> > But typing out restrictedmem is quite tedious, and git grep shows that "rmem" is
> > already used to refer to "reserved memory".
> > 
> > Renaming the syscall to "guardedmem"...
> 
> restrictedmem, guardedmem, ... all fairly "suboptimal" if you'd ask me ...

I'm definitely open to other suggestions, but I suspect it's going to be difficult
to be more precise than something like "guarded".

E.g. we discussed "unmappable" at one point, but the memory can still be mapped,
just not via mmap().  And it's not just about mappings, e.g. read() and its many
variants are all disallowed too, despite the kernel direct map still being live
(modulo SNP requirements).