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AJvYcCUoKxeuDzYpJGPUFp504XGLK7JXndK8oNesRKB7X6tC9jfGG96CzO55W8LIjUYQfvX48OYmxIbZEOvAx63c@vger.kernel.org X-Gm-Message-State: AOJu0YxZlnlKZ63yPGvvzxsMERfe7BKmLZYbCDMXR9/oOhN0hDHySiMN n86BDwfHWlCkZqzNIRvfntf8rm082odSfckktEuJ/E2TVUuxiJE7ElAeuJ6y8vt2E2P4WwdLkea kap8qB58tifHVKz68M+Ke/w== X-Google-Smtp-Source: AGHT+IHesn3dOk6yj3lGjW9oGrsY34nuGC/3KJDKeYlh++dy4L/FXCRUxYHz7/nH0P6zJ+IQHTR/7qIbv4kewoYFFA== X-Received: from pjbso17.prod.google.com ([2002:a17:90b:1f91:b0:301:2679:9d9]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4a85:b0:30a:3dde:6af4 with SMTP id 98e67ed59e1d1-30e2e687a50mr6882572a91.31.1747266186577; Wed, 14 May 2025 16:43:06 -0700 (PDT) Date: Wed, 14 May 2025 16:41:45 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.49.0.1045.g170613ef41-goog Message-ID: <237590b163506821120734a0c8aad95d9c7ef299.1747264138.git.ackerleytng@google.com> Subject: [RFC PATCH v2 06/51] KVM: Query guest_memfd for private/shared status From: Ackerley Tng To: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org Cc: ackerleytng@google.com, aik@amd.com, ajones@ventanamicro.com, akpm@linux-foundation.org, amoorthy@google.com, anthony.yznaga@oracle.com, anup@brainfault.org, aou@eecs.berkeley.edu, bfoster@redhat.com, binbin.wu@linux.intel.com, brauner@kernel.org, catalin.marinas@arm.com, chao.p.peng@intel.com, chenhuacai@kernel.org, dave.hansen@intel.com, david@redhat.com, dmatlack@google.com, dwmw@amazon.co.uk, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, graf@amazon.com, haibo1.xu@intel.com, hch@infradead.org, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgg@ziepe.ca, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, kirill.shutemov@intel.com, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maz@kernel.org, mic@digikod.net, michael.roth@amd.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, pdurrant@amazon.co.uk, peterx@redhat.com, pgonda@google.com, pvorel@suse.cz, qperret@google.com, quic_cvanscha@quicinc.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, quic_svaddagi@quicinc.com, quic_tsoni@quicinc.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, tabba@google.com, thomas.lendacky@amd.com, usama.arif@bytedance.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Content-Type: text/plain; charset="UTF-8" Query guest_memfd for private/shared status if those guest_memfds track private/shared status. With this patch, Coco VMs can use guest_memfd for both shared and private memory. If Coco VMs choose to use guest_memfd for both shared and private memory, by creating guest_memfd with the GUEST_MEMFD_FLAG_SUPPORT_SHARED flag, guest_memfd will be used to provide the private/shared status of the memory, instead of kvm->mem_attr_array. Change-Id: I8f23d7995c12242aa4e09ccf5ec19360e9c9ed83 Signed-off-by: Ackerley Tng --- include/linux/kvm_host.h | 19 ++++++++++++------- virt/kvm/guest_memfd.c | 22 ++++++++++++++++++++++ 2 files changed, 34 insertions(+), 7 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b317392453a5..91279e05e010 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2508,12 +2508,22 @@ static inline void kvm_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, } #ifdef CONFIG_KVM_GMEM_SHARED_MEM + bool kvm_gmem_memslot_supports_shared(const struct kvm_memory_slot *slot); +bool kvm_gmem_is_private(struct kvm_memory_slot *slot, gfn_t gfn); + #else + static inline bool kvm_gmem_memslot_supports_shared(const struct kvm_memory_slot *slot) { return false; } + +static inline bool kvm_gmem_is_private(struct kvm_memory_slot *slot, gfn_t gfn) +{ + return false; +} + #endif /* CONFIG_KVM_GMEM_SHARED_MEM */ #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES @@ -2544,13 +2554,8 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn) return false; slot = gfn_to_memslot(kvm, gfn); - if (kvm_slot_has_gmem(slot) && kvm_gmem_memslot_supports_shared(slot)) { - /* - * For now, memslots only support in-place shared memory if the - * host is allowed to mmap memory (i.e., non-Coco VMs). - */ - return false; - } + if (kvm_slot_has_gmem(slot) && kvm_gmem_memslot_supports_shared(slot)) + return kvm_gmem_is_private(slot, gfn); return kvm_get_memory_attributes(kvm, gfn) & KVM_MEMORY_ATTRIBUTE_PRIVATE; } diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 6f6c4d298f8f..853e989bdcb2 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -865,6 +865,28 @@ bool kvm_gmem_memslot_supports_shared(const struct kvm_memory_slot *slot) } EXPORT_SYMBOL_GPL(kvm_gmem_memslot_supports_shared); +bool kvm_gmem_is_private(struct kvm_memory_slot *slot, gfn_t gfn) +{ + struct inode *inode; + struct file *file; + pgoff_t index; + bool ret; + + file = kvm_gmem_get_file(slot); + if (!file) + return false; + + index = kvm_gmem_get_index(slot, gfn); + inode = file_inode(file); + + filemap_invalidate_lock_shared(inode->i_mapping); + ret = kvm_gmem_shareability_get(inode, index) == SHAREABILITY_GUEST; + filemap_invalidate_unlock_shared(inode->i_mapping); + + fput(file); + return ret; +} + #else #define kvm_gmem_mmap NULL #endif /* CONFIG_KVM_GMEM_SHARED_MEM */ -- 2.49.0.1045.g170613ef41-goog