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AJvYcCUZMjjLAfNoYKgXLsX5CUWYMnf5tPrAS2VeBREQP6s8OeQImObA56ylJ29KDIFpaJEF7jlYlCOaHQ==@kvack.org X-Gm-Message-State: AOJu0Yw980PIab8O/lIlqiiUmNaS7rBxjInpInlWEko6DWIImgs8sI+L 8oZO0IcmI/iUhlqNnW2HbMOxOMfzY5F1eNFhvYmSgTJbkN4JLJgl0MynKnZ8SmuxmrySlUAHLx7 /imHvQLFLXGzGjRYeFjyvvMIap5hw7Y7rAxp8 X-Google-Smtp-Source: AGHT+IGWKDDFm8a8fBCBsG2Y6cToQ+gN2kgFUiQJyVN3BtGBkj0D5sLim/0yEM3t9pwIBqy2Wfftr8DQHh7XIKriiLA= X-Received: by 2002:a05:6512:282b:b0:535:3d14:1313 with SMTP id 2adb3069b0e04-53a14c82458mr25866e87.0.1729189593089; Thu, 17 Oct 2024 11:26:33 -0700 (PDT) MIME-Version: 1.0 References: <1d243dde-2ddf-4875-890d-e6bb47931e40@redhat.com> <20241016225157.GQ3559746@nvidia.com> <20241016235424.GU3559746@nvidia.com> <20241017164713.GF3559746@nvidia.com> <20241017171639.GN3559746@nvidia.com> In-Reply-To: <20241017171639.GN3559746@nvidia.com> From: Vishal Annapurve Date: Thu, 17 Oct 2024 23:56:19 +0530 Message-ID: Subject: Re: [RFC PATCH 26/39] KVM: guest_memfd: Track faultability within a struct kvm_gmem_private To: Jason Gunthorpe Cc: David Hildenbrand , Peter Xu , 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, 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: qpf9idrcu7h451mtcs5fxm7gbuhaczxj X-Rspamd-Queue-Id: CC4AE80019 X-Rspamd-Server: rspam11 X-HE-Tag: 1729189575-860499 X-HE-Meta: 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 LIOIEoS7 lEHE7mCD93H3P5olutO81Mkb/nOZH+RzaRTtGy1oMh/M6anY2qG7qLdR4dY0MA72EqexP1bOgwD9sveKz0majpxfHNUJAd4u3lFfHCcUV/ORha8HLsEOW3Fvwhad5ACECacN3mXZgrKhET0Bt9yjA5mcF+X8Bn2zBqvjRFk19MXKsd7K/ZByjJ8IAa/SAN/oV/asZXo/z47s+RLoM5fkCLrQbDMuRRuWxJyGR8oDbjyqkTvPFu6ySwdFeaYlaLRnxp8EF97VVvqSdSRH3ErHwFYDyH/f0v2eH3hlgThkibPoJCfayfBUiBHlVMCVjpnYLnYInPcG2mbQPVUuJDhdsuQRPd9ronIP6mTV4+H2gMaALh0g8ZMEsV9HOznOdUrwmdQp95jhSP0C2hngii2hjlyWjz77As2R1tUlT1N8OQpybE3g= X-Bogosity: Ham, tests=bogofilter, spamicity=0.011423, 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 10:46=E2=80=AFPM Jason Gunthorpe w= rote: > > On Thu, Oct 17, 2024 at 07:11:46PM +0200, David Hildenbrand wrote: > > On 17.10.24 18:47, Jason Gunthorpe wrote: > > > On Thu, Oct 17, 2024 at 10:58:29AM -0400, Peter Xu wrote: > > > > > > > My question was more torwards whether gmemfd could still expose the > > > > possibility to be used in VA forms to other modules that may not su= pport > > > > fd+offsets yet. > > > > > > I keep hearing they don't want to support page pinning on a guestmemf= d > > > mapping, so VA based paths could not work. > > > > For shared pages it absolutely must work. That's what I keep hearing :) > > Oh that's confusing. I assume non longterm pins desired on shared > pages though?? > > Jason For hugepage support to work, longterm pins on guest private pages need to be avoided [1], If this somehow was the cause of any confusion here. [1] https://lpc.events/event/18/contributions/1764/attachments/1409/3182/LP= C%202024_%201G%20page%20support%20for%20guest_memfd.pdf (slide 12)