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Thu, 01 May 2025 01:07:48 -0700 (PDT) MIME-Version: 1.0 References: <20250430165655.605595-1-tabba@google.com> <20250430165655.605595-9-tabba@google.com> <2b1bf120-99b3-46cd-83bd-b021743540d0@redhat.com> In-Reply-To: <2b1bf120-99b3-46cd-83bd-b021743540d0@redhat.com> From: Fuad Tabba Date: Thu, 1 May 2025 09:07:11 +0100 X-Gm-Features: ATxdqUFLmJfHkI366mwtWMl0YiqPlB-kJX_OyskRiHGx2Beoxdp5LbxHctZZjVM Message-ID: Subject: Re: [PATCH v8 08/13] KVM: guest_memfd: Allow host to map guest_memfd() pages To: David Hildenbrand Cc: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, 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 Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 8A7D440010 X-Stat-Signature: 4fdnb3iisfj8gn1ajkzrdk5gwndndeon X-Rspam-User: X-HE-Tag: 1746086869-35416 X-HE-Meta: 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 jKDqkyDQ E/ljb2Dys0PZKKFLH1eoC1Fbs1gwuCsGFRwazLiN4kXcjD0mT+D+24TGik8FOo9hywjWiV9cKFZ/Rwgza6qRUbua2Epd3KAcDm4ARw6Iu+b+mzjSYCD0otkx8FQQjbQ4Is8D6uLhkF9vHOudQmRaBxdK/LIzFd9kK+jEHp13iZvqoqz13HbGQlDyAzXJ94OhnlLy3SCtxtSwplYwsmFd4ZnFl65MBiIfnWSCgujjol2kH2nx4Mg3ftAcZmo6yUV7NDHYOngPFY8K7xtS4tjy1x/Y+TiuCNR/NBrot9QvGInD+Ltkh7wIV8Ivfwvm3fB+tW9zAQiiBUJHmRxrSHe8h3hgfDQ== 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 Wed, 30 Apr 2025 at 22:33, David Hildenbrand wrote: > > 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. That's right. I'll fix this. Thanks, /fuad > -- > Cheers, > > David / dhildenb >