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Tue, 29 Jul 2025 15:56:05 -0700 (PDT) Date: Tue, 29 Jul 2025 15:54:51 -0700 In-Reply-To: <20250729225455.670324-1-seanjc@google.com> Mime-Version: 1.0 References: <20250729225455.670324-1-seanjc@google.com> X-Mailer: git-send-email 2.50.1.552.g942d659e1b-goog Message-ID: <20250729225455.670324-21-seanjc@google.com> Subject: [PATCH v17 20/24] KVM: arm64: Enable support for guest_memfd backed memory From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Sean Christopherson Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, Ira Weiny , Gavin Shan , Shivank Garg , Vlastimil Babka , Xiaoyao Li , David Hildenbrand , Fuad Tabba , Ackerley Tng , Tao Chan , James Houghton Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250729_155606_492633_8E9477F7 X-CRM114-Status: GOOD ( 10.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Fuad Tabba 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 Signed-off-by: Sean Christopherson --- 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); -- 2.50.1.552.g942d659e1b-goog