guest_memfd就地转换 · v13

新增 kvm_arch_has_gmem_convert() 条件调用 arch 转换钩子，靠死代码消除省去未编译架构开销，为原地转换减少 guest_memfd 元数据开销。

在 kvm_gmem_populate 中用 kvm_mem_is_private() 替代手写属性判断，简化代码，避免后续为 gmem 区间查询另加 API。

用受 filemap_invalidate_lock 保护的 maple tree 记录 guest_memfd 每页私有/共享属性，替换 per-VM 判定，并在 kvm_gmem_get_pfn 提前 folio_put 支持原地转换。

将 KVM_GENERIC_MEMORY_ATTRIBUTES 重命名为 KVM_VM_MEMORY_ATTRIBUTES，明确它只针对 per-VM 属性，为后续 guest_memfd 独立属性解耦 Kconfig。

用 kvm_arch_has_private_mem 是否定义决定是否上报 KVM_MEMORY_ATTRIBUTE_PRIVATE，解除与 KVM_VM_MEMORY_ATTRIBUTES 耦合，避免 arm64 误报并准备 per-gmem 属性。

把 VM 级内存属性 API 统一改名为 kvm_vm 并同步 trace，区分未来 guest_memfd 属性来源，为原地私有/共享转换做准备。

把 kvm_mem_is_private() 改为 kvm_is_private_gfn()，统一 vm/gmem 前缀，便于后续同时存在 VM 与 guest_memfd 两种私有 GFN 查询。

用 static_call 引入通用 kvm_is_private_gfn()，运行时可在 VM 属性与 guest_memfd 查询间切换，原检查改名 kvm_vm_is_private_gfn。

为 guest_memfd 原地私有/共享转换加入全局开关桩，开启后把 __kvm_is_private_gfn 静态调用指向 gmem 查询，使 gmem 成为私有状态唯一权威。

将 kvm_arch_has_private_mem() 桩与 guest_memfd 声明移到 kvm_host.h 现有 #ifdef 区域，减少重复条件编译并聚集私有内存相关定义。

原地转换开启时，移除 guest_memfd folio 时同时失效共享和私有映射，并让 helper 返回映射过滤条件，避免 PUNCH_HOLE 误 zapping 无关共享映射。

in-place 转换开启时设 KVM_MEMSLOT_GMEM_ONLY，使客户机共享/私有页都从 guest_memfd 取，简化 stage2 失效；userspace_addr 仅作普通访问。

给 guest_memfd 失效辅助函数增加映射类型过滤参数，由调用者指定 shared/private/both，为转换时只 zap 目标状态不同的映射做准备。

新增 KVM_SET_MEMORY_ATTRIBUTES2 与更大 attributes2 结构，允许内核写回失败 offset 以支持部分原地转换，并用新 capability 通告。

转换前检查 guest_memfd 页引用，先排空 lru_add 与 mlock fbatch 消除已知伪引用，若仍有 DMA pin 等额外引用则拒绝转换，防止用户态继续写私有内存。

私有转共享时在失效保护下立即调用 arch make_shared 更新硬件元数据；共享转私有留到取 PFN 时按需处理，避免遍历 memslot 并省去无回调开销。

新增区间属性检查，在设置内存属性时若请求范围已全为目标属性就提前返回，减少无意义的转换与失效工作。

把 zeroing/初始化移入 __kvm_gmem_get_pfn，使 populate 路径也先清零，防止原地转换将未初始化宿主页暴露给客户机；用 uptodate 保证只清零一次。

允许 KVM_SEV_SNP_LAUNCH_UPDATE 在 in-place 模式下 uaddr 为 NULL，直接从 guest_memfd 转换已有数据；per-VM 私有跟踪时仍强制提供源地址。

From: Ackerley Tng ackerleytng@google.com Update tdx_gmem_post_populate() to handle cases where userspace requests “no source page”. To handle “no source page”, populate (perform TDH.MEM.PAGE.ADD)

From: Sean Christopherson seanjc@google.com Bury KVM_VM_MEMORY_ATTRIBUTES in x86 to discourage other architectures from adding support for per-VM memory attributes, because tracking private vs. sha

From: Sean Christopherson seanjc@google.com Allow the user to disable KVM_VM_MEMORY_ATTRIBUTES even when KVM supports PRIVATE and SHARED attributes, and expose gmem_in_place_conversion as a module

From: Sean Christopherson seanjc@google.com Now that guest_memfd supports tracking private vs. shared within gmem itself, allow userspace to specify INIT_SHARED on a guest_memfd instance for x86 Co

From: Sean Christopherson seanjc@google.com When adding a memslot associated with a guest_memfd instance, create/dup the guest_memfd before creating the “normal” backing file. This will allow dup'

From: Sean Christopherson seanjc@google.com Rename local variables and function parameters for the guest memory file descriptor and its offset to use a “gmem_” prefix instead of “guest_memfd_”. No

From: Sean Christopherson seanjc@google.com Accept gmem_flags in vm_mem_add() to be able to create a guest_memfd within vm_mem_add(). When vm_mem_add() is used to set up a guest_memfd for a memslo

From: Sean Christopherson seanjc@google.com Add a global variable, kvm_has_gmem_attributes, to make the result of checking for KVM_CAP_GUEST_MEMFD_MEMORY_ATTRIBUTES available to all tests. kvm_has

From: Sean Christopherson seanjc@google.com Add helper functions to kvm_util.h to support calling ioctls, specifically KVM_SET_MEMORY_ATTRIBUTES2, on a guest_memfd file descriptor. Introduce gmem_

From: Ackerley Tng ackerleytng@google.com Add a selftest for the guest_memfd memory attribute conversion ioctls. The test starts the guest_memfd as all-private (the default state), and verifies the

From: Ackerley Tng ackerleytng@google.com Add a test case to verify that conversions between private and shared memory work correctly when the memory is initially created as shared. Co-developed-b

From: Ackerley Tng ackerleytng@google.com The existing guest_memfd conversion tests only use single-page memory regions. This provides no coverage for multi-page guest_memfd objects, specifically w

From: Ackerley Tng ackerleytng@google.com Add two test cases to the guest_memfd conversions selftest to cover the scenario where a conversion is requested before any memory has been allocated in th

[KVM: selftests: Convert with allocated folios in different layouts] From: Ackerley Tng ackerleytng@google.com Add a guest_memfd selftest to verify that memory conversions work correctly with alloc

From: Ackerley Tng ackerleytng@google.com Add a test to verify that deallocating a page in a guest memfd region via fallocate() with FALLOC_FL_PUNCH_HOLE does not alter the shared or private status

From: Sean Christopherson seanjc@google.com Add a test to verify that a guest_memfd’s shared/private status is consistent across processes, and that any shared pages previously mapped in any proces

From: Ackerley Tng ackerleytng@google.com Add helper functions to allow KVM selftests to pin memory using CONFIG_GUP_TEST. This is useful for creating test scenarios where some page has an increase

From: Ackerley Tng ackerleytng@google.com Add a selftest to verify that converting a shared guest_memfd page to a private page fails if the page has an elevated reference count. When KVM converts

From: Ackerley Tng ackerleytng@google.com private_mem_conversions_test used to reset the shared memory that was used for the test to an initial pattern at the end of each test iteration. Then, it w

From: Ackerley Tng ackerleytng@google.com Introduce a new helper, kvm_gpa_to_guest_memfd(), to find the guest_memfd-related details of a memory region that contains a given guest physical address (

From: Sean Christopherson seanjc@google.com Introduce vm_mem_set_memory_attributes(), which handles setting of memory attributes for a range of guest physical addresses, regardless of whether the a

From: Ackerley Tng ackerleytng@google.com The TEST_EXPECT_SIGBUS macro is not thread-safe as it uses a global sigjmp_buf and installs a global SIGBUS signal handler. If multiple threads execute the

From: Ackerley Tng ackerleytng@google.com Currently, vm_mem_add derives the backing source page size, alignment padding, and mmap size from the backing source type upfront before checking if guest_

From: Ackerley Tng ackerleytng@google.com Update private_mem_conversions_test for in-place conversions. In-place conversions support is detected in selftests with kvm_has_gmem_attributes. With in-

From: Sean Christopherson seanjc@google.com Skip setting memory to private in the private memory exits test when using per-gmem memory attributes, as memory is initialized to private by default for