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AJvYcCXQALdN7ZojlhlLWbT4tzGGQP70qVJ9kGiYSM88Z8mLCPqJsz6d3DQRzWRmhZnJpUBRETLfBRzMAQ==@kvack.org X-Gm-Message-State: AOJu0Yy7CS57wGmK7wn//BhD7aEngdKEUBgWaYVfxqLoyBPAbgxL0BEu zUruufh8aqOioBLl0cibb/Drrt/r+6mR0hMuxYUzNbna7vXDmepedvsqN8r+n0WwsOGkGkQKIMF rukjvnA== X-Google-Smtp-Source: AGHT+IE9v+AMqISEN6fUyAdtK8mFeHQvOl0cmpRw928j7ZGnBCeUKwILml7veHgu+g+g3U0uNgaRQdu3bsM= X-Received: from pjbsy11.prod.google.com ([2002:a17:90b:2d0b:b0:31a:aa02:8c50]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1e0b:b0:30a:3e8e:ea30 with SMTP id 98e67ed59e1d1-31e662e841emr4851203a91.11.1753396418146; Thu, 24 Jul 2025 15:33:38 -0700 (PDT) Date: Thu, 24 Jul 2025 15:33:36 -0700 In-Reply-To: Mime-Version: 1.0 References: <20250723104714.1674617-1-tabba@google.com> <20250723104714.1674617-11-tabba@google.com> Message-ID: Subject: Re: [PATCH v16 10/22] KVM: guest_memfd: Add plumbing to host to map guest_memfd pages From: Sean Christopherson To: Xiaoyao Li Cc: Fuad Tabba , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, 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, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com Content-Type: text/plain; charset="us-ascii" X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 83C8C40003 X-Stat-Signature: ocw8q8tidbb967gt6w6nb14mmr3ea8fd X-HE-Tag: 1753396419-580405 X-HE-Meta: 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 tbl8tBAV 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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 Wed, Jul 23, 2025, Xiaoyao Li wrote: > On 7/23/2025 6:47 PM, Fuad Tabba wrote: > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index a1c49bc681c4..e5cd54ba1eaa 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -13518,6 +13518,16 @@ bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) > > } > > EXPORT_SYMBOL_GPL(kvm_arch_no_poll); > > +#ifdef CONFIG_KVM_GUEST_MEMFD > > +/* > > + * KVM doesn't yet support mmap() on guest_memfd for VMs with private memory > > + * (the private vs. shared tracking needs to be moved into guest_memfd). > > + */ > > +bool kvm_arch_supports_gmem_mmap(struct kvm *kvm) > > +{ > > + return !kvm_arch_has_private_mem(kvm); > > +} > > + > > I think it's better to move the kvm_arch_supports_gmem_mmap() stuff to patch > 20. Because we don't know how kvm_arch_supports_gmem_mmap() is going to be > used unitll that patch. No strong preference on my end.