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[2003:cb:c745:a500:7f54:d66b:cf40:8ee9]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a073c9ba61sm18092597f8f.9.2025.04.30.14.33.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Apr 2025 14:33:49 -0700 (PDT) Message-ID: <2b1bf120-99b3-46cd-83bd-b021743540d0@redhat.com> Date: Wed, 30 Apr 2025 23:33:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 08/13] KVM: guest_memfd: Allow host to map 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, pankaj.gupta@amd.com References: <20250430165655.605595-1-tabba@google.com> <20250430165655.605595-9-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-Stat-Signature: 55og7x1k44gbcu1pn9sz5b96uk9ynbbq X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 04C6640003 X-Rspam-User: X-HE-Tag: 1746048834-786108 X-HE-Meta: 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 Tyln8/nf 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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 30.04.25 18:56, Fuad Tabba wrote: > Add support for mmap() and fault() for guest_memfd backed memory > in the host for VMs that support in-place conversion between > shared and private. To that end, this patch adds the ability to > check whether the VM type supports in-place conversion, and only > allows mapping its memory if that's the case. > > This patch introduces the configuration option KVM_GMEM_SHARED_MEM, > which enables support for in-place shared memory. > > It also introduces the KVM capability KVM_CAP_GMEM_SHARED_MEM, which > indicates that the host can create VMs that support shared memory. > Supporting shared memory implies that memory can be mapped when shared > with the host. I think you should clarify here that it's not about "supports in-place conversion" in the context of this series. It's about mapping shared pages only; initially, we'll introduce the option to only have shared memory in guest memfd, and later we'll introduce the option for in-place conversion. -- Cheers, David / dhildenb