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AJvYcCVWjO8u0x4s5G+18ZRVl+fda8S5k2MnO8a98FqXsdvaJNCnn/Vlhrzn2IsQ+Wji0xn4Pk9FnK5J/g==@kvack.org X-Gm-Message-State: AOJu0YyOlJIA+1mnTeDlR+LZWfXH0H2kbgrb+VxG/wAiZ/Rs3F0cAeLt 9VdtX2efy6sIX/rsh02ScResdhcokAnHskZHTrapstAsuJdOwllhYu14kN1czfXKMRp+FBcCG0s B5A== X-Google-Smtp-Source: AGHT+IEHnvYYUOmRrnCbtHPzW+od4gurhsCdgI0yOzILiG8n/NWLWOC3y08BZEdPiw1VxjNfEp1TbYfLTQ== X-Received: from wmbdz10.prod.google.com ([2002:a05:600c:670a:b0:442:ea0c:c453]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:46cc:b0:451:dee4:cd08 with SMTP id 5b1f17b1804b1-454d53d5ec2mr16682175e9.23.1752058824847; Wed, 09 Jul 2025 04:00:24 -0700 (PDT) Date: Wed, 9 Jul 2025 11:59:43 +0100 In-Reply-To: <20250709105946.4009897-1-tabba@google.com> Mime-Version: 1.0 References: <20250709105946.4009897-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250709105946.4009897-18-tabba@google.com> Subject: [PATCH v13 17/20] KVM: arm64: Enable host mapping of shared guest_memfd 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" X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 5FDCA20015 X-Stat-Signature: a8y1kisnczy8t746mwo9rffkapr677ri X-HE-Tag: 1752058826-527702 X-HE-Meta: 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 pZVeu5Af 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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: Enable host userspace mmap support for guest_memfd-backed memory on arm64. This change provides arm64 with the capability to map guest memory at the host directly from guest_memfd: * Define kvm_arch_supports_gmem_mmap() for arm64: The kvm_arch_supports_gmem_mmap() macro is defined for arm64 to be true if CONFIG_KVM_GMEM_SUPPORTS_MMAP is enabled. For existing arm64 KVM VM types that support guest_memfd, this enables them to use guest_memfd with host userspace mappings. This provides a consistent behavior as there are currently no arm64 CoCo VMs that rely on guest_memfd solely for private, non-mappable memory. Future arm64 VM types can override or restrict this behavior via the kvm_arch_supports_gmem_mmap() hook if needed. * Select CONFIG_KVM_GMEM_SUPPORTS_MMAP in arm64 Kconfig. * Enforce KVM_MEMSLOT_GMEM_ONLY for guest_memfd on arm64: Compile and runtime checks are added to ensure that if guest_memfd is enabled on arm64, KVM_GMEM_SUPPORTS_MMAP must also be enabled. This means guest_memfd-backed memory slots on arm64 are currently 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 Acked-by: David Hildenbrand Signed-off-by: Fuad Tabba --- arch/arm64/include/asm/kvm_host.h | 4 ++++ arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/mmu.c | 8 ++++++++ 3 files changed, 13 insertions(+) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index d27079968341..bd2af5470c66 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -1675,5 +1675,9 @@ void compute_fgu(struct kvm *kvm, enum fgt_group_id fgt); void get_reg_fixed_bits(struct kvm *kvm, enum vcpu_sysreg reg, u64 *res0, u64 *res1); void check_feature_map(void); +#ifdef CONFIG_KVM_GMEM +#define kvm_arch_supports_gmem(kvm) true +#define kvm_arch_supports_gmem_mmap(kvm) IS_ENABLED(CONFIG_KVM_GMEM_SUPPORTS_MMAP) +#endif #endif /* __ARM64_KVM_HOST_H__ */ diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 713248f240e0..28539479f083 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_GMEM_SUPPORTS_MMAP help Support hosting virtualized guest machines. diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 71f8b53683e7..b92ce4d9b4e0 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -2274,6 +2274,14 @@ 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. + */ + BUILD_BUG_ON(IS_ENABLED(CONFIG_KVM_GMEM) && !IS_ENABLED(CONFIG_KVM_GMEM_SUPPORTS_MMAP)); + 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); -- 2.50.0.727.gbf7dc18ff4-goog