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[2003:d8:2f02:2900:f54f:bad7:c5f4:9404]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39eae978023sm10531763f8f.47.2025.04.14.03.01.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 14 Apr 2025 03:01:27 -0700 (PDT) Message-ID: Date: Mon, 14 Apr 2025 12:01:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 2/9] KVM: guest_memfd: Handle final folio_put() of guest_memfd pages To: Fuad Tabba , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.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, 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_eberman@quicinc.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, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com References: <20250318161823.4005529-1-tabba@google.com> <20250318161823.4005529-3-tabba@google.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Stat-Signature: b5npjs66omm68dguhqk1jyyipws4fb34 X-Rspam-User: X-Rspamd-Queue-Id: E1F4D4000F X-HE-Tag: 1744624892-793727 X-HE-Meta: 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 SZVEEckQ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 18.03.25 17:18, Fuad Tabba wrote: > Before transitioning a guest_memfd folio to unshared, thereby > disallowing access by the host and allowing the hypervisor to > transition its view of the guest page as private, we need to be > sure that the host doesn't have any references to the folio. > > This patch introduces a new type for guest_memfd folios, which > isn't activated in this series but is here as a placeholder and > to facilitate the code in the subsequent patch series. This will > be used in the future to register a callback that informs the > guest_memfd subsystem when the last reference is dropped, > therefore knowing that the host doesn't have any remaining > references. > > This patch also introduces the configuration option, > KVM_GMEM_SHARED_MEM, which toggles support for mapping > guest_memfd shared memory at the host. > > Signed-off-by: Fuad Tabba > Acked-by: Vlastimil Babka > Acked-by: David Hildenbrand > --- Same with this patch for now. -- Cheers, David / dhildenb