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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 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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