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AJvYcCWLwrolgc5yhm+5FB33RBUIG/6dvGfpU5v1GtsdO9QMdNEmGgl2yCYmuLJ/01DrDd02A+mY2HvBmg==@kvack.org X-Gm-Message-State: AOJu0YyPIbI+5kKayAdaKfTSzE0f0njQKIy69wQoX1Zr6xm9SiQnh6wl 2AaQHbNGwx0ei1IcD1WTsh7O+mFq2Wrv3T1mwJU7PaMs/u+WTqwEbriyltB/gk1YGhAxtxS+Kwy liV3Z2lIWzDnoLLY42xFej/Lycfvjlhr/v5u7 X-Gm-Gg: ASbGnctDwLRquarNwENWTe45beyRBxnwGJewd1tG8J2EMpWfD3cC0bJs4mDn3cpnWC9 TpqVCifJ61medGpcOcrjP3wIrW00hXsPdcoPHavGff+Ug37WRe3pULAiMTfgSHiE1qAAmb2Aybb XzCrRIZb42BRqrcDLMsTM/aO5x/PeUVopT8D5zIab1WA2HcewUJ2KXt7+F5K28Gcg= X-Google-Smtp-Source: AGHT+IFiewDsh+KtQaHc0+sMyr5WyQmEk6swjiDZjCjdcy6OqRcTDauDDFEFO1+U8aLuAUaLbLYDQ/fh6Pt9jjFl3vM= X-Received: by 2002:a05:690c:6a13:b0:702:4eb0:6af with SMTP id 00721157ae682-70a3fb50442mr71919297b3.31.1746824077805; Fri, 09 May 2025 13:54:37 -0700 (PDT) MIME-Version: 1.0 References: <20250430165655.605595-1-tabba@google.com> <20250430165655.605595-9-tabba@google.com> In-Reply-To: <20250430165655.605595-9-tabba@google.com> From: James Houghton Date: Fri, 9 May 2025 13:54:02 -0700 X-Gm-Features: AX0GCFvn133p0WfcWXRvPwPeSy4C7Kx4OsjhoiQ9viApK0YRW3SBt1Ynv90_jo0 Message-ID: Subject: Re: [PATCH v8 08/13] KVM: guest_memfd: Allow host to map guest_memfd() pages To: Fuad Tabba 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, david@redhat.com, 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, peterx@redhat.com, pankaj.gupta@amd.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 1740C18000E X-Stat-Signature: d874ipsa6r7su4ta5qgyccnf35nqenxd X-Rspam-User: X-HE-Tag: 1746824078-759681 X-HE-Meta: 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 qm6lSNjO 4FJAFacVeRYDt1PHz1Cd5FJdVeNtiOOgWk7cMk4vwLM/rs1hYsQULwXjUuZd3Ml7ZBWq8ofnzYhqy5t3OH0awOLCz4DCXKPqdS9j4Raiil81gZ6JJKdmo9Mamqk9sQ63R7CYqJalzL2oDc/QU1W275wqn55b+6dpN+yRhqWPoRYcGGZAyFgr1IsQlTI54y8ZdrD1jr2t45c7Kexccj8FEzpegsO4ZYgwj3quaxd6TfGGoaDASGacCOLrTf7y97BirxKOfawdiZJDkUh7xZ4EfpToEaY0FHwkqk0695gX+4ciwqKENN9gtFKsJecRyk1HCN8bGRqTjgIhlR3uCxS3SRSIM4//EJF9X5Zrs7xAOkyAvmuJyyWbZk+BBz631ija0oZ6j 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, Apr 30, 2025 at 9:57=E2=80=AFAM Fuad Tabba wrote= : > +static int kvm_gmem_mmap(struct file *file, struct vm_area_struct *vma) > +{ > + struct kvm_gmem *gmem =3D file->private_data; > + > + if (!kvm_arch_gmem_supports_shared_mem(gmem->kvm)) > + return -ENODEV; > + > + if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) !=3D > + (VM_SHARED | VM_MAYSHARE)) { > + return -EINVAL; > + } > + > + vm_flags_set(vma, VM_DONTDUMP); Hi Fuad, Sorry if I missed this, but why exactly do we set VM_DONTDUMP here? Could you leave a small comment? (I see that it seems to have originally come from Patrick? [1]) I get that guest memory VMAs generally should have VM_DONTDUMP; is there a bigger reason? [1]: https://lore.kernel.org/kvm/20240709132041.3625501-9-roypat@amazon.co.= uk/#t > + vma->vm_ops =3D &kvm_gmem_vm_ops; > + > + return 0; > +}