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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6cc22959ae2sm30837856d6.93.2024.10.17.12.11.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Oct 2024 12:11:14 -0700 (PDT) Date: Thu, 17 Oct 2024 15:11:10 -0400 From: Peter Xu To: Jason Gunthorpe Cc: David Hildenbrand , Ackerley Tng , tabba@google.com, quic_eberman@quicinc.com, roypat@amazon.co.uk, rientjes@google.com, fvdl@google.com, jthoughton@google.com, seanjc@google.com, pbonzini@redhat.com, zhiquan1.li@intel.com, fan.du@intel.com, jun.miao@intel.com, isaku.yamahata@intel.com, muchun.song@linux.dev, erdemaktas@google.com, vannapurve@google.com, qperret@google.com, jhubbard@nvidia.com, willy@infradead.org, shuah@kernel.org, brauner@kernel.org, bfoster@redhat.com, kent.overstreet@linux.dev, pvorel@suse.cz, rppt@kernel.org, richard.weiyang@gmail.com, anup@brainfault.org, haibo1.xu@intel.com, ajones@ventanamicro.com, vkuznets@redhat.com, maciej.wieczor-retman@intel.com, pgonda@google.com, oliver.upton@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH 26/39] KVM: guest_memfd: Track faultability within a struct kvm_gmem_private Message-ID: References: <1d243dde-2ddf-4875-890d-e6bb47931e40@redhat.com> <20241016225157.GQ3559746@nvidia.com> <20241016235424.GU3559746@nvidia.com> <20241017164713.GF3559746@nvidia.com> <20241017171010.GK3559746@nvidia.com> MIME-Version: 1.0 In-Reply-To: <20241017171010.GK3559746@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Rspamd-Queue-Id: 00752120018 X-Rspamd-Server: rspam01 X-Stat-Signature: eiyyh6p7i5ig4c1s84kznkmmbhrck6tt X-HE-Tag: 1729192270-918542 X-HE-Meta: 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 vzFHgbhi 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000040, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Oct 17, 2024 at 02:10:10PM -0300, Jason Gunthorpe wrote: > > If so, maybe that's a non-issue for non-CoCo, where the VM object / > > gmemfd object (when created) can have a flag marking that it's > > always shared and can never be converted to private for any page > > within. > > What is non-CoCo? Does it include the private/shared concept? I used that to represent the possible gmemfd use cases outside confidential computing. So the private/shared things should still be around as fundamental property of gmemfd, but it should be always shared and no convertion needed for the whole lifecycle of the gmemfd when marked !CoCo. Basically, that's the KVM-only hugetlbfs v2.. especially if this series will move on with hugetlb allocators, that's even closer.. which makes some sense to me at least for now to avoid reinvent the wheels all over the places over cgroup/pool/meminfo/etc. -- Peter Xu