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AJvYcCVkvoZOob5YrRjhqLjxNgTyU4ICAwm2SXjT6dXE1kmFqnsRYewgcViCKxJvqOR5aph9BfBF310=@lists.linux.dev X-Gm-Message-State: AOJu0YxfwBgyUvQU+xkPzbi3+qLCYDHqqcOiPNrtJMb/He+MlhEe2fUf Pb4Mj+LFVksafFuLg30tEtgQ1xdL0kMWdOS1ldi7BieJ46kP27vwox1aSQWChk8VeC6Jnb3C7BO snQ== X-Google-Smtp-Source: AGHT+IGyaKsC329OBN9V1qxHlr9H7PRQZ93BDS0adc/MtT4FbbSuIMkwbSVam8vf8SbmIv3tftcMpfJ1jQ== X-Received: from wrbcg16.prod.google.com ([2002:a5d:5cd0:0:b0:3a4:e199:883b]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:4201:b0:3b4:9dbd:eee9 with SMTP id ffacd0b85a97d-3b768ef951bmr1536942f8f.36.1753267655654; Wed, 23 Jul 2025 03:47:35 -0700 (PDT) Date: Wed, 23 Jul 2025 11:47:11 +0100 In-Reply-To: <20250723104714.1674617-1-tabba@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250723104714.1674617-1-tabba@google.com> X-Mailer: git-send-email 2.50.1.470.g6ba607880d-goog Message-ID: <20250723104714.1674617-20-tabba@google.com> Subject: [PATCH v16 19/22] KVM: arm64: Enable support for guest_memfd backed memory From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev 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, 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, tabba@google.com Content-Type: text/plain; charset="UTF-8" Now that the infrastructure is in place, enable guest_memfd for arm64. * Select CONFIG_KVM_GUEST_MEMFD in KVM/arm64 Kconfig. * Enforce KVM_MEMSLOT_GMEM_ONLY for guest_memfd on arm64: Ensure that guest_memfd-backed memory slots on arm64 are only supported if they are intended for shared memory use cases (i.e., kvm_memslot_is_gmem_only() is true). This design reflects the current arm64 KVM ecosystem where guest_memfd is primarily being introduced for VMs that support shared memory. Reviewed-by: James Houghton Reviewed-by: Gavin Shan Reviewed-by: Marc Zyngier Acked-by: David Hildenbrand Signed-off-by: Fuad Tabba --- arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/mmu.c | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 713248f240e0..bff62e75d681 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -37,6 +37,7 @@ menuconfig KVM select HAVE_KVM_VCPU_RUN_PID_CHANGE select SCHED_INFO select GUEST_PERF_EVENTS if PERF_EVENTS + select KVM_GUEST_MEMFD help Support hosting virtualized guest machines. diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 8c82df80a835..85559b8a0845 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -2276,6 +2276,13 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, if ((new->base_gfn + new->npages) > (kvm_phys_size(&kvm->arch.mmu) >> PAGE_SHIFT)) return -EFAULT; + /* + * Only support guest_memfd backed memslots with mappable memory, since + * there aren't any CoCo VMs that support only private memory on arm64. + */ + if (kvm_slot_has_gmem(new) && !kvm_memslot_is_gmem_only(new)) + return -EINVAL; + hva = new->userspace_addr; reg_end = hva + (new->npages << PAGE_SHIFT); -- 2.50.1.470.g6ba607880d-goog